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Karabatsiakis 2023 MiP2023 + ('''Authors:''' [[Karabatsiakis Alexander]] … '''Authors:''' [[Karabatsiakis Alexander]], [[Manrique Juan-Salinas]], [[Stoll Thomas]], [[Hennessy Thomas]], [[Hill Michelle M]], [[Dietrich Detlef E]] Major depressive disorder (MDD) is characterized by impairments in mental and physical performance. Despite intensified hypothesis-driven research, applicable biomarkers for MDD are missing. Research showed that MD is associated with impaired mitochondrial bioenergetic functioning in peripheral blood mononuclear cells (PBMC). However, deeper biomolecular insights into bioenergetic and associated biochemical changes in blood underlying the pathophysiology of MDD are necessary to identify new biomarker candidates. Here, the biochemistry of PBMC-surrounding blood was analyzed using a hypothesis-free biomarker identification approach combining metabolite and lipid fingerprinting. Biochemical fingerprints of serum were compared between female individuals (N = 44) with and without MDD. Serum extracts were separated by liquid chromatography and detected with time-of-flight mass spectrometry. The data was analyzed by multiple group comparisons and correlations, as well as two multivariate classification procedures. Next, our previously identified alterations in mitochondrial bioenergetics in PBMC were co-considered as an outcome for our biomarker identification approach. Consequently, the most promising compound was tested for correlation with mitochondrial respiration. Nine biomarker candidates discriminated between MDD and non-MDD with high predictive accuracy (90.9 %). The detected compounds are involved in lipid and amino acid-metabolism. ''9,10-dihydroxy-octadenedioic acid'' was revealed as a robust biomarker candidate with a predictive accuracy of 81.8 % and significant mean positive correlation with parameters of mitochondrial respiration (r = 0.31-0.48, p<0.01). Our fingerprinting results highlight novel biomarker candidates and associated pathways for MDD research. The unraveled biochemical pathways indicate a modulated association of MDD with inflammation, oxidative stress, and mitochondrial bioenergetics. The biomarker candidates have to be replicated in independent cohorts of all ages & sexes.be replicated in independent cohorts of all ages & sexes.)
Zouhar 2023 MiP2023 + ('''Authors:''' [[Kopecky Jan]] … '''Authors:''' [[Kopecky Jan]], [[Zouhar Petr]], [[Janovska Petra]], [[Bardova K]], [[Otahal J]], [[Vrbacky Marek]], [[Mracek Tomas]], [[Adamcova K]], [[Lenkova L]], [[Funda J]], [[Cajka T]], [[Drahota Zdenek]], [[Stanic S]], [[Rustan Arild C]], [[Horakova Olga]], [[Houstek Josef]], [[Rosmeissl M]] Heat production is essential for maintaining a constant body temperature, and is an important component of energy balance. Well-described mechanisms involved in heat generation include shivering of muscle and non-shivering thermogenesis (NST) in brown adipose tissue (BAT). Thermogenesis in BAT, which is dependent on the presence of the mitochondrial protein UCP1, is the focus of interest for its potential use in the treatment of obesity. Other mechanisms of NST and their significance are relatively poorly understood. We have shown [1] that obesity-resistant A/J mice acclimated to cold failed to increase adrenergically stimulated NST in BAT and activated NST in skeletal muscle instead. Heat generation in muscle involved increased calcium ion cycling in the endoplasmic reticulum associated with higher mitochondrial oxidative activity. The involvement of different thermogenic mechanisms could be related to the different susceptibility to obesity. The resistance of A/J mice to obesity may result, at least in part, from their ability to activate NST in muscle. Such mechanism may provide a more promising way to treat obesity than potential therapies based on increasing thermogenesis in BAT, as the capacity of skeletal muscle of adult human to burn fat energy stores is several fold greater than in BAT. Thus, only a relatively small increase in thermogenesis in muscle could significantly reduce adipose tissue deposition. How to achieve such an increase is a challenge for further research. # Janovska P et al., 2023, Mol Metab. https://doi.org/10.1016/j.molmet.2023.101683Metab. https://doi.org/10.1016/j.molmet.2023.101683 )
Mahapatra 2023 MiP2023 + ('''Authors:''' [[Mahapatra Gargi]] … '''Authors:''' [[Mahapatra Gargi]], [[Gao Zhengrong]], [[Bateman James R III]], [[Lockhart Samuel Neal]], [[Bergstrom Jaclyn]], [[Craft Suzanne]], [[Molina Anthony JA]] Impaired glucose tolerance (IGT), including prediabetes and diabetes, increases risk of developing age related disorders, including Alzheimer’s disease (AD). We analyzed mitochondrial bioenergetics in platelets collected from 208 adults, 55 years and older, with or without insulin sensitivities (112 normoglycemics (NG), 96 IGTs). Platelets from IGT participants exhibited unique bioenergetic profiles exemplified by higher mitochondrial respiration than NG. IGT platelets exhibited higher glucose-dependent maximal (Max) and spare respiratory (SRC) capacities compared to NG, and higher fatty acid oxidation-dependent maximal coupled (MaxOXPHOS) and uncoupled (MaxETS) respiration compared to NG. Correlating bioenergetics from all 208 participants combined with glucose measures (OGTT_120, OGTT_AUC, and HbA1c) revealed significant positive associations. Most associations were unaltered with age, sex, and BMI adjustments. Further separating NG and IGT participants and correlating platelet respiration with glucose measures revealed distinct trends in NG versus IGT group. In NG, previously observed associations remained intact, and new significant positive associations emerged between platelet bioenergetics and HbA1c. Associations in IGT group were overall negative. Identifying systemic mitochondrial mechanisms that associate with glucose intolerance in older adults will help in monitoring pathological progression of AD in relation to comorbidities such as insulin sensitivity, and supports the development of minimally invasive biomarkers of AD.# Mahapatra G, Gao, Bateman JR III, Lockhart SN, Bergstrom J, DeWitt AR, Piloso JE, Kramer PA, Gonzalez-Armenta JL, Amick A, Casanova R, Craft S, Molina AJA (2022) Blood-Based Bioenergetic Profiling Reveals Differences in Mitochondrial Function Associated with Cognitive Performance and Alzheimer’s Disease Alzheimer's & Dementia 2022. https://doi.org/10.1002/alz.12731 & Dementia 2022. https://doi.org/10.1002/alz.12731 )
Nagwani 2023 MiPschool Obergurgl + ('''Authors:''' [[Nagwani Amit K]] … '''Authors:''' [[Nagwani Amit K]], [[Kaczmarek L]], [[Kmita H]] '''Introduction:''' Tardigrades are considered as one of the toughest animals on Earth due to their remarkable ability to withstand extreme condition. An example of these conditions is hypomagnetic field (HMF, static magnetic field with an intensity <5 μT), which is known to influence the metabolic processes including mitochondria functioning. However, very few studies considering HMF impact were performed for organisms able to survive under extreme conditions and considered as suitable for outer space colonization. Therefore, we decided to check the impact of HMF on the tardigrade ''Paramacrobiotus experimentalis'' focusing on mitochondria functionality reflected by the mitochondrial inner membrane potential (ΔΨ) having regard to age and sex. '''Methods:''' Females and males from 3 different age classes (i.e., 30-60, 150-180 and >300 days) were extracted from laboratory culture and divided into experimental and control groups exposed to HMF and standard magnetic field (SMF), respectively, for three different durations i.e., 7 days, 15 days and 30 days. The HMF treatment was performed in a special anti-magnetic chamber whereas SMF treatment was performed in a climate chamber. TMRM staining of intact animals was used to estimate ΔΨ. '''Results and discussion:''' The calculated FITMRM index indicated HMF-related changes in Δψ dependent on age and sex. Accordingly, HMF effect was most pronounced for the oldest animals and males appeared to be more sensitive to HMF than females that correlated with the survival rate. The results provide an insight into mechanisms of HMF effect that could be useful for organization of space travels and living outside the Earth. # Mo W, Liu Y, He R. (2014) Hypomagnetic field, an ignorable environmental factor in space? https://doi.org/10.1007/s11427-014-4662-x# Binhi VN, Prato FS (2017) Biological effects of the hypomagnetic field: An analytical review of experiments and theories. https://doi.org/10.1371/journal.pone.0179340# Conley CC (1970) A Review of the biological effects of very low magnetic fields. NASA. Technical Note; TN D-5902: 1–27. https://ntrs.nasa.gov/citations/19700024915# Erdmann W, Idzikowski B, Kowalski W, Kosicki J, Kaczmarek Ł (2021) Tolerance of two anhydrobiotic tardigrades Echiniscus testudo and Milnesium inceptum to hypomagnetic conditions. https://doi.org/10.7717/peerj.10630scus testudo and Milnesium inceptum to hypomagnetic conditions. https://doi.org/10.7717/peerj.10630 )
Owesny 2023 MiP2023 + ('''Authors:''' [[Owesny Patricia]] … '''Authors:''' [[Owesny Patricia]], [[Hegemann N]], [[Kuebler WM]], [[Ost Mario]], [[Grune T]], [[Ott C]] Cardiac aging is a multifactorial process, which is associated with increased oxidative stress, cell death and mitochondrial abnormalities. These factors can lead to an overall impairment of cardiac function and substrate utilization [1,2]. With the increased prevalence of obesity and related comorbidities, especially coronary heart disease, it was proposed that obesity could present a condition of premature heart aging [3]. Therefore, our aim is to compare the impact of obesity and aging on heart function, as well as the cardiac energy metabolism, focusing on mitochondria. Our experimental design of diet-induced obesity contains three different age groups (22, 76 and 106 weeks), where male C57BL/6J mice receive either a High fat/High-carb or a Standard diet for 8 weeks. After dietary intervention, mice underwent echocardiographic or metabolic treadmill analysis. Heart tissue was used for the Oroboros O2k measurement of mitochondrial bioenergetics. In further studies of cardiac energy metabolism Western blot and qPCR in heart tissue and isolated cardiomyocytes were performed. Echocardiography revealed a decline in cardiac output in mice 76 and 106 weeks of age with a further decrease by High fat/High-carb diet. Interestingly, these effects were more pronounced in 76 weeks group. In the same group we investigated indications of an impaired mitochondrial energy metabolism, specifically associated with cardiomyocytes. Although, loss of cardiac function with age has been previously described, we demonstrate here a key role for mitochondrial energy metabolism in this loss of function. # Houtkooper R H, Argmann C, Houten S M, Cantó C, Jeninga E H, Andreux P A, Thomas C, Doenlen R, Schoonjans K, Auwerx J (2011), The metabolic footprint of aging in mice. https://doi.org/10.1038/srep00134. # Lazzeroni D, Villatore A, Souryal G, Pili G, Peretto G (2022), The Aging Heart: A Molecular and Clinical Challenge. https://doi.org/10.3390/ijms232416033.# Ren J, Dong F, Cai G-J, Zhao P, Nunn J M, Wold L E, Pei J (2010), Interaction between age and obesity on cardiomyocyte contractile function: role of leptin and stress signaling. https://doi.org/10.1371/journal.pone.0010085.n and stress signaling. https://doi.org/10.1371/journal.pone.0010085. )
Petrick 2023 MiP2023 + ('''Authors:''' [[Petrick Heather L]] … '''Authors:''' [[Petrick Heather L]], [[Aussieker T]], [[Fuchs CJ]], [[Hermans WJ]], [[Betz MW]], [[Pinckaers PJM]], [[Snijders T]], [[van Loon LJC]], [[Holloway Graham P]] '''Introduction:''' Mitochondrial ADP sensitivity represents an important control point in oxidative phosphorylation. The sensitivity of mitochondria to ADP is lower in high-lipid environments, in aging males, and in young females compared to young males. However, the interaction between sex, age, and body composition (fat mass) in the regulation of mitochondrial ADP sensitivity remains unknown. '''Methods:''' Vastus lateralis muscle biopsies were obtained from healthy, recreationally active, young males (n=21, 24±4 y, 22.7±2.2 kg/m2 BMI), young females (n=20, 21±2 y, 21.7±2.2 kg/m2), older males (n=13, 76±5 y, 25.8±2.5 kg/m2), and older females (n=6, 70±6 y, 23.4±3.0 kg/m2). Permeabilized fibers were prepared to measure mitochondrial ADP sensitivity. Whole-body DEXA scans were performed. Data (mean±SD) were analyzed using two-way ANOVAs. '''Results and discussion:''' Body fat percentage was higher in females and older individuals (main effects). While maximal mitochondrial respiration did not differ between groups, mitochondrial ADP sensitivity was affected by sex and age. Specifically, in younger individuals mitochondrial ADP sensitivity was lower in females compared with males (~15 % higher apparent ADP Km, p=0.02). Older males also showed ~15% lower mitochondrial ADP sensitivity compared with young males (p=0.04). In contrast to young individuals, mitochondrial ADP sensitivity was numerically greater (~15 %) in older females when compared with older males (p=0.14) and younger females (p=0.12). However, there were no correlations between body fat percentage and mitochondrial apparent ADP Km in any group. We speculate that sex-based differences in mitochondrial ADP sensitivity are impacted by estrogen as opposed to body composition, as this response is lost with aging. ADP sensitivity are impacted by estrogen as opposed to body composition, as this response is lost with aging. )
Phang 2023 MiP2023 + ('''Authors:''' [[Phang Howard J]] … '''Authors:''' [[Phang Howard J]], [[Gerwick W]], [[Molina Anthony JA]] Mitochondrial bioenergetic decline is a well known biological hallmark of aging, suggesting that mitochondria-targeting therapeutics have great potential in treating age-related diseases and conditions [1]. Despite this, their efficacy within the context of human aging remains largely unknown. We sought to develop a phenotypic screening platform to identify agents that directly modulate mitochondrial function in human cells. Marine natural products (MNP) represent a large, under-explored chemical space with immense therapeutic potential [2]. We screened a MNP library of 125 pure compounds at 10, 1, and 0.1 µg/mL incubated for 24 hours with with primary human dermal fibroblasts (pHDF) as summarized in Figure 1. We leveraged the San Diego Nathan Shock Center which houses 50+ pHDF lines derived from healthy donors across a spectrum of adult age. Cultured pHDF retain age-related phenotypes including mitochondrial bioenergetic decline, which presents a robust opportunity to identify bioenergetic effects within the context of human aging [3]. Thus, we used pHDF from a donor representative of an “older” phenotype (74 years of age) to ensure aging relevance. We identified numerous compounds that modulate mitochondrial function in a dose-dependent manner. Our primary outcomes were change in basal or maximal respiration using high throughput respirometry (Agilent Seahorse XFe96). This screening platform successfully identified compounds with stimulatory as well as inhibitory effects on respiratory capacity. Future steps include further validation of hit compounds using high-resolution respirometry on the Oroboros O2k. These studies will elucidate mechanistic effects on the electron transfer system as well as effects on cells of different donor ages. # Murphy MP, Hartley RC (2018) Mitochondria as a therapeutic target for common pathologies. https://doi.org/10.1038/nrd.2018.174.# Liang X, Luo D, Luesch H (2018) Advances in exploring the therapeutic potential of marine natural products. https://doi.org/10.1016/j.phrs.2019.104373. # Auburger G, Klinkenberg M, Drost J, Marcus K, Morales-Gordo B, Kunz WS, Brandt U, Broccoli V, Reichmann H, Gispert S, Jendrach M (2012). Primary Skin Fibroblasts as a Model of Parkinson's Disease. https://doi.org/10.1007/s12035-012-8245-1. Parkinson's Disease. https://doi.org/10.1007/s12035-012-8245-1. )
Piel 2023 MiP2023 + ('''Authors:''' [[Piel Sarah]] … '''Authors:''' [[Piel Sarah]], [[cManus Meagan J]], [[Heye K]], [[Beaulieu F]], [[Fazeliniae H]], [[Janowska Joanna I]], [[McTurk B]], [[Starr Jonathan]], [[Gaudio H]], [[Patel N]], [[Hefti MM]], [[Smalley M]], [[Hook JF]], [[Kohli NV]], [[Bruton J]], [[Hallowell T]], [[Delso N]], [[Roberts A]], [[Lin Y]], [[Ehinger Johannes K]], [[Karlsson Michael]], [[Berg RA]], [[Morgan RW]], [[Kilbaugh Todd J]] '''Introduction:''' Despite advancements in cardiopulmonary resuscitation (CPR), secondary neurological injury remains the key determinant of successful recovery from cardiac arrest (CA) [1-3]. Currently, there are no established clinical therapies that preserve neurological function [4]. We previously found that acute decline in mitochondrial health up to 24 hours post-CA correlated with poor neurological outcome [5-6]. Here, we tested the potential of dimethyl fumarate (DMF), a derivative of the TCA-cycle intermediate fumaric acid shown to enhance mitochondrial bioenergetics [7], to improve mitochondrial injury in brain and heart following successful resuscitation after CA. '''Methods:''' Female piglets representing toddler age underwent asphyxia, followed by ventricular fibrillation, cardiopulmonary resuscitation and defibrillation until return of spontaneous circulation. Subsequently, animals received daily treatment with DMF or vehicle. Sham animals underwent identical anesthesia protocols and instrumentation without CA. After 4 days, animals (n=5 of each group) were euthanized, tissues were harvested and their mitochondrial function, quantity and proteomic profile was analyzed. '''Results and discussion:''' Mitochondrial content and function, as measured by citrate synthase activity and high-resolution respirometry, was reduced at 4 days following CA. In contrast, myocardial mitochondria demonstrated a complete restoration of mitochondrial content and function despite persistent changes in mitochondrial ultrastructure. DMF treatment prevented 25 % of the long-term proteomic changes in the brain, including proteins related to mitochondrial bioenergetics and oxidative stress. In addition, myocardial mitochondrial morphology was normalized by DMF. In this model of CA, mitochondria sustained persistent damage in an organ-specific manner. DMF partially prevents these long-term mitochondrial changes in myocardium and brain.# Berg RA et al: Incidence and Outcomes of Cardiopulmonary Resuscitation in PICUs. Crit Care Med 2016; 44(4):798-808# Slomine BS, Silverstein FS, Christensen JR, et al: Neurobehavioural outcomes in children after In-Hospital cardiac arrest. Resuscitation 2018; 124:80-89# Laver S, Farrow C, Turner D, et al: Mode of death after admission to an intensive care unit following cardiac arrest. Intensive Care Med 2004; 30(11):2126-2128# Neumar RW et al: Post-Cardiac Arrest Syndrome. Circulation 2008; 118(23):2452-2483# Lautz AJ, Morgan RW, Karlsson M, et al: Hemodynamic-Directed Cardiopulmonary Resuscitation Improves Neurologic Outcomes and Mitochondrial Function in the Heart and Brain. Critical care medicine 2019; 47(3):e241-e249# Kilbaugh TJ, Sutton RM, Karlsson M, et al: Persistently Altered Brain Mitochondrial Bioenergetics After Apparently Successful Resuscitation From Cardiac Arrest. Journal of the American Heart Association 2015; 4(9):e002232# Hayashi G, Jasoliya M, Sahdeo S, et al: Dimethyl fumarate mediates Nrf2-dependent mitochondrial biogenesis in mice and humans. Human molecular genetics 2017; 26(15):2864-2873ice and humans. Human molecular genetics 2017; 26(15):2864-2873 )
Pytlak 2023 MiP2023 + ('''Authors:''' [[Pytlak Karolina]] … '''Authors:''' [[Pytlak Karolina]], [[Maliszewska – Olejniczak K]], [[Sek Aleksandra]], [[Szewczyk Adam]], [[Bednarczyk Piotr]], [[Kulawiak Bogusz]] Human bronchial epithelial (HBE) cells form an external barrier in the airways and are constantly exposed to factors such as urban dust. Recently, the large conductance calcium-activated potassium (mitoBKCa) channel has been identified in the inner mitochondrial membrane of HBE cells. The pore-forming subunit of the channel is encoded by the ''KCNMA1'' gene, which also encodes plasma membrane BKCa channels. Mitochondrial potassium channels regulate mitochondrial membrane potential, oxygen consumption, mitochondrial volume and reactive oxygen species synthesis. Activation of mitoBKCa induces cytoprotection of cardiac and brain tissue. In our project, we applied CRISPR/Cas9 technique to disrupt ''KCNMA1'' gene in the HBE cell line (16HBE14o- cells). The newly formed line showed no mitoBKCa channel activity. We also noticed changes related to the deregulation of the cell cycle. The loss of mitoBKCa significantly affected mitochondrial function. We observed a decrease in the rate of mitochondrial respiration. Furthermore, we analyzed the organization of respiratory chain complexes using Blue Native electrophoresis. In addition, analysis of the expression of selected genes encoding mitochondrial proteins showed changes in cells with disrupted ''KCNMA1'' gene. Nevertheless, a thorough understanding of the observed mitochondrial dysfunction requires further study.We conclude that the presence of the mitoBKCa channel in HBE cells is essential for the preservation of mitochondrial function and is important for the proper function of these cells as part of the human airways. for the preservation of mitochondrial function and is important for the proper function of these cells as part of the human airways. )
Sadler 2023 MiP2023 + ('''Authors:''' [[Sadler Daniel]] … '''Authors:''' [[Sadler Daniel]], [[Treas L]], [[Ross T]], [[Sikes JD]], [[Britton SL]], [[Koch LG]], [[Borsheim Elisabet]], [[Porter Craig]] '''Introduction:''' Low cardiorespiratory fitness (CRF) is associated with a greater risk for metabolic disease. The potential for early life exercise training to overcome metabolic perturbations imparted by low intrinsic CRF remains unknown. We tested the hypothesis that early life exercise training would overcome whole-body and tissue metabolic defects imparted by low CRF.'''Methods:''' At 26 days of age, rat low-capacity runners (LCR, ''n''=20) and high-capacity runners (HCR, ''n''=20) generated by artificial selection were assigned to either sedentary control (CTRL, n=10) or voluntary wheel running (VWR, ''n''=10) for 6 weeks. Post-intervention, whole-body metabolic phenotyping was performed, and the respiratory function of isolated skeletal muscle and liver mitochondria assayed. Quantitative proteomics were performed on tissue samples.'''Results and discussion:''' HCR-VWR performed 1.8-fold greater volume of wheel running than LCR-VWR (P<0.001). In LCR, VWR reduced body fat (''P''<0.001), increased total daily energy expenditure (+16 %, ''P''=0.030), and enhanced glucose tolerance (''P''=0.040). Muscle mitochondrial respiratory function was unaffected by VWR in both strains, although VWR increased muscle mitochondrial protein content (both ''P''<0.05). VWR enhanced the respiratory capacity of HCR hepatic mitochondria (+23 %, ''P''=0.040). Proteomic analyses revealed lower capacity for fatty acid oxidation in muscle and liver of LCR-CTRL versus HCR-CTRL, which was not rescued by VWR. VWR reduced hepatic pyruvate kinase abundance in both strains (both ''P''<0.013), indicating VWR may shift fuel preferences of hepatic mitochondria. These results reveal early life exercise training partially overcomes the metabolic phenotype imparted by low intrinsic CRF, although proteomic adaptations to early exercise training remain influenced by intrinsic CRF. to early exercise training remain influenced by intrinsic CRF. )

('''Authors:''' [[Sadler Daniel]], [[Treas L]], [[Ross T]], [[Sikes JD]],)

Saleem 2023 MiPschool Obergurgl + ('''Authors:''' [[Saleem Ranim]] … '''Authors:''' [[Saleem Ranim]], [[Scott Graham R]] '''Introduction:''' High-altitude environments are characterized by cold temperatures and low O2 levels (hypoxia). Small mammals at high altitude thus face the metabolic challenge of maintaining thermogenesis to cope with cold in a hypoxic environment that can constrain aerobic ATP supply. Circulatory O2 delivery by the heart is essential for supporting tissue O2 demands, but it is unclear whether evolved or plastic changes in cardiac mitochondria help overcome constraints on thermogenesis in high-altitude environments. '''Method:''' We examined this issue in deer mice (Peromyscus maniculatus). Mice from populations native to high altitude and low altitude were born and raised in captivity, and adults were acclimated to warm (25 °C) normoxia or cold (5 °C) hypoxia (~12 kPa O2 for 5-6 weeks) in a full-factorial design. Mitochondrial function was studied by high-resolution respirometry and fluorometry in permeabilized tissue from left ventricles and was complemented by assays of several metabolic and antioxidant enzymes. '''Results and discussion:''' Mitochondrial capacities for oxidative phosphorylation and electron transport were similar between populations and were unaffected by acclimation to cold hypoxia, as were activities of citrate synthase and cytochrome oxidase. However, exposure to cold hypoxia increased activities of lactate dehydrogenase, which were also greater in highlanders than in lowlanders, likely to augment capacities for lactate oxidation. Furthermore, mitochondrial emission of reactive oxygen species was lower in highlanders than in lowlanders across environments, associated with lower levels of lipid peroxidation and protein carbonyls. Therefore, phenotypic plasticity and evolved changes in cardiac mitochondria help deer mice cope with metabolic challenges at high altitude. evolved changes in cardiac mitochondria help deer mice cope with metabolic challenges at high altitude. )
Saucedo-Rodriguez 2023 MiP2023 + ('''Authors:''' [[Saucedo-Rodriguez Maria Jose]] … '''Authors:''' [[Saucedo-Rodriguez Maria Jose]], [[Pecina Petr]], [[Cunatova Kristyna]], [[Vrbacky Marek]], [[Cajka T]], [[Mracek Tomas]], [[Pecinova Alena]] '''Introduction:''' Succinate dehydrogenase (SDH) connects the TCA cycle by oxidizing succinate to fumarate and the respiratory chain by transferring electrons to ubiquinone. Mutations in SDH subunits have been associated with tumorigenesis as well as mitochondrial diseases. In this project, we focused on the flavoprotein subunit A of SDH (SDHA) which is primarily associated with inherited mitochondrial disease [1] and investigated the consequences of this subunit loss in HEK cells (SDHA KO). '''Methods:''' We performed structural and functional characterizations of the SDHA KO model involving protein electrophoresis to study OXPHOS complexes and subcomplexes, label-free quantification of protein levels, measurement of cellular respiration using high-resolution respirometry and determination of NAD+/NADH levels. '''Results and discussion:''' Together with SDHA, other SDH subunits were downregulated as well, leading to the absence of assembled SDH. Moreover, a secondary downregulation of the majority of complex I and IV subunits was observed. The cellular respiratory capacity was severely decreased in the model, with SDH-dependent respiration completely abolished and complex I-dependent respiration attenuated reflecting the downregulation of respiratory chain complexes in general. Finally, the NAD+/NADH ratio was increased in SDHA KO compared to the controls, indicating complex rearrangement of the TCA. The SDHA KO cells thus represent a suitable model to study metabolic rewiring and the effect of pathogenic SDHA mutations. # Rustin, P., Munnich, A., & Rötig, A. (2002). Succinate dehydrogenase and human diseases: new insights into a well-known enzyme. https://doi.org/10.1038/sj.ejhg.5200793 d human diseases: new insights into a well-known enzyme. https://doi.org/10.1038/sj.ejhg.5200793 )
Schoenfeld 2023 MiP2023 + ('''Authors:''' [[Schoenfeld Peter|Schönfeld P]], … '''Authors:''' [[Schoenfeld Peter|Schönfeld P]], [[Reiser G]] Distinct hypothalamic neurons sense blood levels of fatty acids (FA) and, thereby regulate caloric intake. Astrocytes have some capacity of β-oxidation. But, there are ongoing discussions on this question: Do neurons generally burn FA for energy generation?Respiration and membrane potential of mitochondria of rat brain (RBM) and, for comparison, of liver (RLM) were measured without and with octanoate (l-octanoylcarnitine). In addition, H2O2 generation was measured with Amplex Red.In line with previous studies, we found no evidence for a noteworthy β-oxidation of FA by RBM. This fits with theoretical considerations (1) and values obtained for capacities of enzymes of β-oxidation (2). But, these results contradict those of a previous study (3), reporting that RBM incubated with mixtures of FA (carnitine derivatives) plus other substrates (e.g. succinate) show substantial β-oxidation. What could be possible reasons for disregarding FA as energy substrates by neurons? These are mainly: (a) Harmful activities of non-esterified long-chain FA on mitochondria. (b) Burning of FA costs more oxygen than glucose burning with respect to the energy yield. (c) FA oxidation by mitochondria is associated with more sites of superoxide generation. (d) Neurons are equipped with poor antioxidative capacity. In conclusion, burning of FA would expose neurons to intolerably high oxidative stress.# Speijer D (2011] Oxygen radicals shaping evolution: Why fatty acid catabolism leads to peroxisomes while neurons do without it. https://doi.org/10.1002/bies.201000097# Yang SY, He XY, Schultz H (1987) Fatty acid oxidation in rat brain is limited by the low activity of 3-ketoacyl-coenzyme A thiolase. https://doi.org/10.1016/S0021-9258(18)45161-7# Panov A, Orynbayeva Z, Vavilin V, Lyakhovich V (2014) Fatty acids in energy metabolism of the central nervous system. https://doi.org/10.1155/2014/472459tabolism of the central nervous system. https://doi.org/10.1155/2014/472459 )
Sobotka 2023 MiP2023 + ('''Authors:''' [[Sobotka Lubos]] … '''Authors:''' [[Sobotka Lubos]], [[Sobotka Ondrej]] Obesity is associated with insulin resistance, which is the cause of subsequent metabolic complications, including increased morbidity. Despite several decades of efforts to prevent the growth of obesity, its incidence continues to increase. We do not even know what ratio of nutrients is optimal for preventing obesity and insulin resistance, and the optimal ratio of carbohydrates to lipids has not been proven. Some studies, including calorimetric measurements performed at our workplace, have shown that the oxidation of individual substrates does not correspond to their ratio in the given diet. However, this apparent paradox makes sense because food intake in humans is intermittent and usually does not occur during increased or even maximal physical activity. Energy and metabolic substrates are stored in the body during intake and are subsequently mobilized during periods of starvation and physical activity. As a result, the human body is never in true energy balance; storage and subsequent mobilization of energy is necessary for a functioning organism. In addition, carbohydrates, fats and proteins are not only a source of energy, but also important substances with many functions [1]. After ingestion of a mixed meal, carbohydrates (especially glucose) are used for both oxidation and non-oxidative pathways (antioxidant, anaplerotic, cataplerotic processes). Only a relatively small fraction of glucose is a source for new lipid synthesis. Ingested fats are preferentially stored in adipose tissue and does not influence carbohydrate oxidation. The lack of glucose can explain more insulin resistance in whole organism than Randle cycle measured in vitro conditions [2].# Sobotka L, Sobotka O. The predominant role of glucose as a building block and precursor of reducing equivalents. https://doi.org/10.1097/mco.0000000000000786 # Sobotka O, et al. Should Carbohydrate Intake Be More Liberal during Oral and Enteral Nutrition in Type 2 Diabetic Patients? https://doi.org/10.3390/nu15020439in Type 2 Diabetic Patients? https://doi.org/10.3390/nu15020439 )
Stanic 2023 MiPschool Obergurgl + ('''Authors:''' [[Stanic Sara]] … '''Authors:''' [[Stanic Sara]], [[Janovska Petra]], [[Zouhar Petr]], [[Bardova K]], [[Otahal J]], [[Vrbacky Marek]], [[Mracek Tomas]], [[Adamcova K]], [[Lenkova L]], [[Funda J]], [[Cajka T]], [[Drahota Zdenek]], [[Rustan Arlid C]], [[Horakova Olga]], [[Houstek Josef]], [[Rosmeissl M]], [[Kopecky Jan]] '''Introduction:''' Non-shivering thermogenesis (NST) is an energy-dissipating process that occurs in brown adipose tissue (BAT) and is activated by the adrenergic system. Earlier studies found that cold induces adrenergically activated NST in obesity-prone C57BL/6 (B6) mice, but not in obesity-resistant A/J mice. To investigate this difference, we studied the effect of cold acclimation on muscle NST. '''Methods:''' Palmitoyl carnitine oxidation and cytochrome c oxidase (COX) activity (TMPD+ascorbate and KCN) was measured in muscle homogenates of A/J and B6 mice acclimated to 30 °C or to 6 °C using Oroboros Oxygraph. In parallel, amount of mitochondrial supercomplexes was assessed by Blue native electrophoresis. '''Results and discussion:''' As expected, muscle of A/J mice exhibited higher amount of Scaf1 dependent supercomplex III2IV than muscle of B6 mice, and this amount was further increased by cold acclimation. Both palmitoyl carnitine oxidation and COX activity were induced by cold in A/J but not in B6 mice. The higher oxidation capacity of muscle of cold acclimated A/J mice, possibly connected with supercomplex composition, may indicate that muscle represents the site of alternative NST instead of BAT in these mice. The distinct mechanism of NST could correspond to obesity resistance of this strain. # Janovska P. et al (2023) Impairment of adrenergically-regulated thermogenesis in brown fat of obesity-resistant mice is compensated by non-shivering thermogenesis in skeletal muscle. https://doi.org/10.1016/j.molmet.2023.101683rmogenesis in skeletal muscle. https://doi.org/10.1016/j.molmet.2023.101683 )
Stankova 2023 MiP2023 + ('''Authors:''' [[Stankova Pavla]] … '''Authors:''' [[Stankova Pavla]], [[Peterova E]], [[Dusek J]], [[Elkalaf Moustafa]], [[Cervinkova Zuzana]], [[Kucera Otto]] '''Introduction:''' In our previous study in a murine model of nonalcoholic steatohepatitis (NASH), we found reduced succinate-activated hepatic mitochondrial respiration and accumulation of succinate, a proinflammatory, profibrogenic, and oncogenic metabolite [1]. According to preliminary studies, telmisartan, an angiotensin II type 1 receptor blocker, positively affects insulin resistance and liver steatosis. This project aimed to investigate the effect of telmisartan on NASH in mice. '''Methods:''' The NASH was induced in male mice fed a western-style diet (WD) for 36 weeks. During the last 6 weeks of the experiments, mice were administered daily telmisartan (oral gavage, 5 mg/kg b.w./day). Liver and epididymal fat histological changes were evaluated (Hematoxylin-eosin, Sirius red). Body parameters, plasma liver profile (VetScan), hepatic triglycerides, cholesterol, and the expression of selected proteins (WB/ELISA) and genes (qRT-PCR) were assessed. Mitochondrial respiration of liver homogenates was measured by high-resolution respirometry (OROBOROS Oxygraph-2k). Using Reporter Gene assay, telmisartan's activation of nuclear receptors was evaluated on HepG2 cells. '''Results and discussion:''' Administration of telmisartan to mice fed a WD reduced absolute and relative liver weight and visceral adipose tissue weight, activities of ALT and AST, liver steatosis, and inflammation grade. These effects were accompanied by a significant increase in succinate-activated respiration in the ET state and the activity of succinate dehydrogenase. We confirmed that telmisartan is a PPAR-γ partial agonist and described the activating effect of telmisartan on the CAR receptor for the first time. Telmisartan appears to be a promising safety drug for treating NASH that affects metabolism at multiple levels. # Staňková P, Kučera O, Peterová E, Elkalaf M, Rychtrmoc D, Melek J, Podhola M, Zubáňová V, Červinková Z (2021) Western Diet Decreases the Liver Mitochondrial Oxidative Flux of Succinate: Insight from a Murine NAFLD Model. https://doi.org/10.3390/ijms22136908ght from a Murine NAFLD Model. https://doi.org/10.3390/ijms22136908 )
Stiles 2023 MiP2023 + ('''Authors:''' [[Stiles Linsey]] … '''Authors:''' [[Stiles Linsey]], [[Fernandez-del-Rio L]], [[Beninca C]], [[Acin-Perez R]], [[Shirihai Orian]] Impaired mitochondrial function has been shown to play a key role in diseases of metabolism and aging. Respirometry is the gold standard measurement of mitochondrial function, as it is an integrated metabolic readout of the final step of the electron transport chain (ETC). However, analysis of mitochondrial respiratory function in tissue requires processing and measurement of freshly isolated mitochondria. This requirement makes respirometry impracticable for standard clinical practice, clinical studies, retrospective studies, and higher throughput respirometry. We have validated a methodology to measure maximal mitochondrial oxygen consumption rates through Complex I, II, and IV of the ETC in previously frozen biological samples using Agilent XF Analyzers. Additionally, Complex V (CV) ATP hydrolytic activity can be measured with the pH channel. These measurements of Complex I-V activities are specific as demonstrated by inhibition with ETC inhibitors. Additionally, these approaches can be applied to tissue homogenates, which simplifies the sample preparation and reduces the required starting material compared with isolating mitochondria. We find that primary changes in the maximal respiratory capacity, detected in fresh tissue, are preserved in frozen samples. These techniques to measure mitochondrial maximal respiratory function and CV hydrolytic activity in frozen samples makes clinical mitochondrial assessment more feasible and adds a complementary approach to investigate the role of mitochondrial function in disease onset and progression.tochondrial function in disease onset and progression.)
Timon-Gomez 2023 MiP2023 + ('''Authors:''' [[Timon-Gomez Alba]] … '''Authors:''' [[Timon-Gomez Alba]], [[Cardoso Luiza HD]], [[Doerrier Carolina]], [[Garcia-Souza Luiz F]], [[Gnaiger Erich]] '''Introduction:''' Mitochondrial dysfunction in muscle tissue is associated with obesity (mitObesity) and its comorbidities. Many drugs and nutraceuticals used to treat these conditions target mitochondria. Early diagnosis of mitObesity is crucial for understanding the link between obesity, mitochondrial dysfunction, and its associated chronic comorbidities. Respirometry of mitochondrial preparations can assess electron transfer pathways and coupling in oxidative metabolism with high diagnostic resolution [1]. '''Methods:''' We developed a standardized protocol for functional diagnosis of mitochondrial defects using high-resolution respirometry [2]. This substrate-uncoupler-inhibitor titration (SUIT) protocol analyzes fatty acid oxidation (FAO) by adding 0.1 mM malate and octanoylcarnitine, with consideration of malate-linked anaplerosis to avoid overestimation of FAO [3-4]. The protocol is extended to stimulate the NADH-linked pathway by adding pyruvate and glutamate. Then succinate and glycerophosphate are titrated to investigate convergent CoQ-reducing pathways. A stepwise titration of uncoupler CCCP allows quantification of the electron transfer capacity. Residual oxygen consumption is assessed after inhibition by rotenone and antimycin A. '''Results and discussion:''' To quantify FAO, malate was needed to avoid inhibition by accumulating acetyl-CoA. However, in the presence of mitochondrial malic enzyme, 2 mM malate stimulated respiration through the NADH-linked pathway in liver and brain mitochondria. Anaplerotic activity above endogenous respiration was minimized at a low (0.1 mM) malate concentration and subtracted from respiration obtained after addition of octanoylcarnitine. This SUIT reference protocol can be used as a general diagnostic tool for bioenergetic profiling in various sample preparations from different cell types, tissues, and organisms. # Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. https://doi.org/10.26124/bec:2020-0002# Doerrier C, Garcia-Souza LF, Krumschnabel G, Wohlfarter Y, Mészáros AT, Gnaiger E (2018) High-Resolution FluoRespirometry and OXPHOS protocols for human cells, permeabilized fibers from small biopsies of muscle, and isolated mitochondria. https://doi.org/10.1007/978-1-4939-7831-1_3 # Ojuka E, Andrew B, Bezuidenhout N, George S, Maarman G, Madlala HP, Mendham A, Osiki PO (2016) Measurement of β-oxidation capacity of biological samples by respirometry: a review of principles and substrates. https://doi.org/10.1152/ajpendo.00475.2015# Bernstine EG, Koh C, Lovelace CC (1979) Regulation of mitochondrial malic enzyme synthesis in mouse brain. https://www.doi.org/10.1073/pnas.76.12.6539synthesis in mouse brain. https://www.doi.org/10.1073/pnas.76.12.6539 )
Strich 2023 MiPschool Obergurgl + ('''Authors:''' [[Torres-Quesada Omar]] … '''Authors:''' [[Torres-Quesada Omar]], [[Strich Sophie]], [[Feichtner Andreas]], [[Schwaighofer Selina]], [[Doerrier Carolina]], [[Schmitt Sabine]], [[Gnaiger Erich]], [[Stefan Eduard]] Protein kinases play an important role in numerous signaling pathways regulating cell proliferation, cell cycle, and metabolism. Deregulation of kinase functions have been connected to various human diseases, such as cancer [1]. In recent years, kinase inhibitors have gained recognition by aiming to block single or multiple oncogenic kinase pathways [2]. In these lines, blockade of kinase activities has been shown to converge on the central energetic organelle, the mitochondria [3, 4]. Furthermore, colon cancer cells rely on mitochondrial OXPHOS as major source of energy, contradicting the Warburg effect [5]. To increase the understanding of small molecule-based kinase blockers and their cell-type-specific adverse effects, we set out to record the impact of kinase drugs on mitochondrial respiration using High-resolution FluoRespirometry in several colon cancer cell models. We observed that the impact of kinase inhibitors depends on the mutational background of the tested cancer cell lines as well as on cell culture medium formulations [6]. First, we detected off-target effects of sunitinib, an FDA-approved multikinase blocker, only in a more physiological cell culture medium as compared with classical formulations. Second, mitochondrial profiling of the glycolytic kinase inhibitor PFK158 revealed off-target mitochondrial dysfunction. Third, we were able to show that inhibition of kinase signaling is connected to mitochondrial reactive oxygen species (ROS), which can be influenced by protein kinase modulators. In summary, cell-based mitochondrial bioenergetic profiles have the power to identify off-target effects of kinase inhibitors and allow a detailed mechanistic insight on drug-induced perturbations in cancer cell metabolism.# Cohen, P, Cross, D, Jänne, PA (2021). Kinase drug discovery 20 years after imatinib: progress and future directions. Nat Rev Drug Discov. 20(7):551-569. https://doi.org/10.1038/s41573-021-00195-4 # Zhang J, Yang PL, Gray NS (2009). Targeting cancer with small molecule kinase inhibitors. https://doi.org/10.1038/nrc2559 # Wallace, DC (2012). Mitochondria and Cancer Nat. Rev. Cancer, 12, 685–698. https://doi.org/10.1038/nrc3365 # Torres-Quesada O, Strich S, Stefan E (2022). Kinase perturbations redirect mitochondrial function in cancer. Bioenerg. Commun. 2022,13. https://doi.org/10.26124/bec:2022-0013# Sun, X., Zhan, L., Chen, Y. et al. (2018) Increased mtDNA copy number promotes cancer progression by enhancing mitochondrial oxidative phosphorylation in microsatellite-stable colorectal cancer. Sig Transduct Target Ther 3, 8. https://doi.org/10.1038/s41392-018-0011-z # Torres-Quesada, O, Doerrier, C, Strich, S, Gnaiger, E, Stefan, E (2022). Physiological Cell Culture Media Tune Mitochondrial Bioenergetics and Drug Sensitivity in Cancer Cell Models. Cancers, 14, 3917. https://doi.org/10.3390/cancers14163917ancers, 14, 3917. https://doi.org/10.3390/cancers14163917 )
Ullrich 2023 MiPschool Obergurgl + ('''Authors:''' [[Ullrich Volker]] … '''Authors:''' [[Ullrich Volker]], [[Heidler Juliana]], [[Schildknecht S]], [[Daiber Andreas]], [[Frensch M]], [[Wittig Ilka]], [[Bruene B]] '''Introduction:''' Micelles containing cardiolipin (CL) and phosphatidylcholine in presence of cytochrome ''c'' (Cytc) and H2O2 were reported to catalyze peroxidationes of typical peroxidase substrates but also of CL itself (Kagan et. al, Biochem. 45,4998, 2006). This can be explained by complex formation of CL with Cytc under removal of the Met80 sixth ligand of the heme. '''Methods:''' O2 consumption was measured polarographically (Orobos Instruments) and diene formation spectrally at 237 nm. '''Results and Discussion:''' Cytc addition to CL micelles caused a burst of O2 uuptake that could be repeated until CL or O2 were depleted. About 4.5 mol of O2/mol CL were taken up forming products with mainly 2,4,6 or 8 additional O-atoms. Diene formation initially followed the same kinetics but stopped or was reversed before O2 uptake was completed. In presence of 2 M KCl Cytc acted catalytically with slower kinetics in three phases and showed oxidative modifications of the protein. The required peroxide tone originated from autoxidized CL and was upregulated during progress of the reaction. Significance for the process of opening of the permeability pore is suggested. autoxidized CL and was upregulated during progress of the reaction. Significance for the process of opening of the permeability pore is suggested. )