Leukemia represents as one of the most common primary malignancies of the hematologic system in both children’s and adults and remains a largely incurable or relapse disease. The elucidation of disease subtypes based on mutational profiling, has not improved clinical outcomes. IDH1/2 are key enzymes of TCA cycle that produces α-ketoglutarate (αKG), however their mutated version, are well reported in various cancer types including leukemia, produces D-2 hydroxyglutarate (D-2HG), an oncometabolite. Recently, some studies have shown that wild type IDH1 is highly expressed in non-small cell lung carcinoma (NSCLC), primary glioblastomas (GBM) and several hematological malignancies and corelates with disease progression. In this work, we have showed treatment of wild type IDH1 leukemia cells with specific IDH1 inhibitor switched leukemic cells towards gly-colysis from oxidative phosphorylation (OXPHOS) phenotype. We also noticed reduction in αKG in treated cells possible suggesting inhibition of IDH1 enzymatic activity. Further, we found that IDH1 inhibition reduces the metabolites related to one carbon metabolism, essential to maintain global methylation in leukemic cells. Finally, we observed that metabolic alteration in IDH1 inhibitor treated leukemic cells promotes reactive oxygen species (ROS) formation along with loss of mito-chondrial membrane potential, leading towards apoptosis in leukemic cells. Overall, we showed that wild type IDH1 targeting in leukemic cells promote metabolic alterations that can be exploited for combination therapies for better outcome.

Telomeres – special DNA-protein structures at the ends of linear eukaryotic chromosomes define the proliferation potential of cells. Extremely short telomeres promote DNA damage response and cell death to eliminate cells potentially accumulated mutations after multiple divisions. However, telomere elongation is associated with increased proliferative potential of special types of cells, such as stem and germ cells, permanently, and is activated temporally in processes of activation of immune response, regeneration processes. Activation of mechanisms of telomere lengthening coupled with increased proliferation and with requirements of cells in energy and building resourses. To obtain necessary nutrients cells stimulate metabolism by switching of oxidative phosphorylation program to glycolysis. In this review we focused on the interconnection of metabolism program and telomere lengthening mechanisms known for the situation of the programmed activation of proliferation such as germ cells maturation, early embryonic development program and immune response activation. Here, we propose that it is possible to reprogram metabolism in order to regulate the telomere length, proliferative activity of cells that may be important for the development of approaches to regeneration, immune response modulation and cancer therapy and further investigations in this area are necessary to improve the understanding and manipulating of molecular mechanisms used for regulation of proliferation.

Abstract: Oxidative metabolism is crucial for leukemic stem cell (LSC) function and drug resistance in acute myeloid leukemia (AML). Mitochondrial metabolism also affects the immune system and therefore the antitumor response. Modulation of oxidative phosphorylation (OxPHOS) has emerged as a promising approach to improve therapy outcome for AML patients. However, the effect of mitochondrial inhibitors on the immune compartment in the context of AML is yet to be explored. Immune checkpoints such as the ecto-nucleotidase CD39 and programmed dead ligand 1 (PD-L1) have been reported to be expressed in AML and linked to chemoresistance and poor prognosis. In the present study, we first demonstrated that a novel selective electron transfer chain complex (ETC) I inhibitor, EVT-701, decreased OxPHOS metabolism of murine and human cytarabine (AraC)-resistant leukemic cell lines. Furthermore, we showed that, while AraC induced immune response regulation by increasing CD39 expression and by reinforcing interferon-γ/PD-L1 axis, EVT-701 reduced CD39 and PD-L1 expression in vitro in a panel of both murine and human AML cell lines, especially upon AraC treatment. Altogether, this work uncovers a non-canonical function of ETCI in controlling CD39 and PD-L1 immune checkpoints, thereby improving the anti-tumor response in AML.

It has been long recognized that under hypoxia conditions cancer cells reprogram their metabolism through shift from oxidative phosphorylation (OXPHOS) to glycolysis to meet elevated requirements in energy and nutrients for proliferation, migration and survival. However, data accumulated over the last years increasingly evidence that cancer cells can revert from glycolysis to OXPHOS and maintain both reprogrammed and oxidative metabolism even in the same tumor. The phenomenon denoted as cancer cell metabolic plasticity or hybrid metabolism depends on a tumor micro-environment, which is highly heterogeneous and influenced by intensity of vasculature and blood flow, oxygen concentration, nutrient and energy supply, and requires regulatory interplay between multiple oncogenes, transcription factors, growth factors, reactive oxygen species (ROS), etc. Hypoxia-inducible factor-1 (HIF-1) and AMP-activated protein kinase (AMPK) represent key modulators of switch between reprogrammed and oxidative metabolism. The present review focuses on cross-talks between HIF-1, GLUTs, and AMPK and other regulatory proteins including oncogenes such as c-Myc, p53 and KRAS, growth factor-initiated PKB/Akt, PI3K and mTOR signaling pathways and tumor suppressors such as LKB1 and TSC1 in controlling cancer cell metabolism. The multiple switches between metabolic pathways can underlie chemo-resistance to conventional anti-cancer therapy and should be taken into account in choosing molecular targets to discovery novel anti-cancer drugs.

When exposed to a viral infection, the attacked cells promptly set up defence mechanisms. Part of antiviral responses, the innate immune interferon pathway and associated interferon stimulated genes are notably allowing the production of proteins bearing an antiviral activity. Numerous viruses are able to evade the interferon response, highlighting the importance of controlling this pathway to ensure their efficient replication. Several viruses are also known to manipulate the metabolism of infected cells to optimize the availability of amino acids, nucleotides and lipids. They then benefit from a reprogramming of the metabolism that favours glycolysis instead of mitochondrial respiration. Given the increasingly discussed crosstalk between metabolism and innate immunity, we wondered whether this switch from glycolysis to mitochondrial respiration would be beneficial or deleterious for an efficient antiviral response. We used a cell based model of metabolic reprogramming. Interestingly, we showed that increased mitochondrial respiration was associated with an enhanced interferon response following poly:IC stimulation. This suggests that during viral infection, the metabolic reprogramming towards glycolysis is also part of the virus' strategies to inhibit the antiviral response.

Acute myeloid leukaemia (AML) is characterized by the accumulation of undifferentiated blast cells in the bone marrow and blood. In most AMLs, relapse frequently occurs due to resistance to chemotherapy. Compelling research results indicate that drug resistance in cancer cells is highly dependent on the intracellular levels of reactive oxygen species (ROS). Modulating ROS levels is therefore a valuable strategy to overcome the chemotherapy resistance of leukemic cells. In this study, we evaluated the efficiency of diphenyleneiodonium (DPI), a well-known inhibitor of ROS production, in targeting AML cells. Results showed that although inhibiting cytoplasmic ROS production, DPI triggered an increase in the mitochondrial ROS levels caused by the disruption of the mitochondrial respiratory chain. We also demonstrated that DPI blocks the mitochondrial oxidative respiration (OxPhos) in a dose-dependent manner and that AML cells with high OxPhos status were highly sensitive to treatment with DPI, which synergizes with the chemotherapeutic agent cytarabine (Ara-C). Thus, our results suggest that targeting mitochondrial function by DPI might be exploited to target AML cells with high OxPhos status.

Flashes of superoxide anion (SA) in mitochondria are generated spontaneously or during the opening of the permeability transition pore (PTP) and a sudden change in the metabolic state of a cell. Under certain conditions, SA can leave the mitochondrial matrix and perform signaling functions beyond mitochondria. In this work, we studied the kinetics of the release of SA and H2O2 from isolated mitochondria upon PTP opening and the modulation of the metabolic state of mitochondria by the substrates of respiration and oxidative phosphorylation. It was found that PTP opening leads to suppression of H2O2 emission and activation of SA burst. When the induction of PTP was blocked by its antagonists (cyclosporine A, ruthenium red, EGTA), the level of substrates of respiration and oxidative phosphorylation and the selective inhibitors of complexes I and V determined the type of ROS emitted by mitochondria. It was concluded that upon complete and partial reduction and complete oxidation of redox centers of the respiratory chain, mitochondria emit H2O2, SA, and nothing, respectively. The results indicate that the PTP- and substrate-dependent switching of the type of ROS leaving mitochondria may be the basis for SA- and H2O2-selective redox signaling in a cell.

In a 24-week-long experiment, 31 rats were assigned to one of 3 groups: a Control group receiving standard chow and water, a Fructose group receiving standard chow and a 20% fructose solution, or an STZ+lipids group that received a fat-enriched diet following a single 25 mg/kg streptozotocin injection at the onset of the diet. Both groups experienced significantly increased caloric intake but did not gain weight above the Control group level. Adipocytes in subcutaneous and visceral adipose depots of both groups had smaller size compared to control and higher density in tissue. Respirometric analyses unveiled a substantial increase in mitochondrial respiration across all adipose tissue types in both dietary intervention groups, with greater changes observed in the Fructose group. Correlation analyses demonstrated that in both experimental groups high tissue respiration is associated with better biochemical profile and closer to control adipose tissue morphology. Increased tissue respiration in adipose depots could be an important mechanism of resilience to excessive caloric intake.

Abstract: Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder with extensive genetic and aetiological heterogeneity. While the underlying molecular mechanisms involved remain unclear, significant progress has been facilitated by recent advances in high-throughput transcriptomic, epigenomic and proteomic technologies. Here, we review recently published ASD proteomic data and compare proteomic func-tional enrichment signatures to those of transcriptomic and epigenomic data. We iden-tify canonical pathways that are consistently implicated in ASD molecular data and find an enrichment of pathways involved in mitochondrial metabolism and neurogenesis. We identify a subset of differentially expressed proteins that are supported by ASD tran-scriptomic and DNA methylation data. Furthermore, these differentially expressed proteins are enriched for disease phenotype pathways associated with ASD aetiology. These proteins converge on protein-protein interaction networks that regulate cell pro-liferation and differentiation, metabolism and inflammation which demonstrates a link between canonical pathways, biological processes and the ASD phenotype. This review highlights how proteomics can uncover potential molecular mechanisms to explain a link between mitochondrial dysfunction and neurodevelopmental pathology.

Oxidative phosphorylation (OxPhos) is the basic function of mitochondria although the land-scape of mitochondrial functions is continuously growing to include more aspects of cellular homeostasis. Thanks to the application of -omics technologies to the study of the OxPhos system, novel features emerge from the cataloging of novel proteins as mitochondrial thus adding de-tails to the mitochondrial proteome and defining novel metabolic cellular interrelations, espe-cially in the human brain. We focussed on the diversity of bioenergetics demand and different aspects of mitochondrial structure, functions, and dysfunction in the brain. Definition as ‘mitoexome’, ‘mitoproteome’ and ‘mitointeractome’ have entered the field of ‘mitochondrial medicine’. In this context, we reviewed several genetic defects that hamper the last step of aerobic metabolism mostly involving the nervous tissue as one of the most prominent energy-dependent tissues and, as consequence, as a primary target of mitochondrial dysfunction. The dual genetic determination of the OxPhos complexes is one of the reasons for the complexity of the geno-type-phenotype correlation when facing human diseases associated with mitochondria defects; clinically, are characterized by extremely heterogeneous symptoms, ranging from organ-specific to multisystemic dysfunction with different clinical courses. Finally, we briefly discuss the fu-ture directions of the multi-omics study of human brain disorders.

ATP is the most universal and essential energy molecule in the eukaryotic cell. This is due to its ability to store energy in form of high energy phosphate bonds, which are extremely stable and readily usable by the cell. This energy is key for a variety of biological functions such as cell growth and division, metabolism, signalling, and for the turnover of biomolecules. Understanding how ATP is produced and hydrolysed with a spatiotemporal resolution is necessary to understand its functions both in physiological and pathological contexts. In this review, we will first describe the ATP synthase, the main molecular motor for ATP production in mitochondria. Second, we will review the biochemical assays currently available to estimate ATP quantities in cells, and we will compare their readouts, strengths and weaknesses. Then, we will explore the palette of genetically-encoded biosensors designed for microscope-based approaches and show how their spatiotemporal resolution opened up the possibility to follow ATP levels and production in living cells. Finally, we will comment on how ATP monitoring is used in preclinical practices, and to what extent genetically-encoded sensors could be used as a promising tool to elucidate pathologies in which ATP is implicated.

We report the case of a four-year-old male patient with a complex medical history born prematurely as the result of intrauterine growth restriction due to placental insufficiency. His clinical manifestations include severe neurodevelopmental deficits, global developmental delay, Pierre-Robin sequence, and intractable epilepsy with both generalized and focal features. The proband’s low levels of citrulline and lactic acidosis provoked by administration of depakoke are evocative of a mitochondrial etiology. However, the genotype-phenotype correlation remains undefined in the absence of nuclear and mitochondrial pathogenic variants detected by deep sequencing of both genomes. However, live-cell mitochondrial metabolic investigations provide evidence of a deficient oxidative phosphorylation pathway responsible for ATP synthesis, leading to chronic energy crisis in the proband. In addition, our metabolic analysis reveals metabolic plasticity in favor of glycolysis for ATP synthesis. Our mitochondrial morphometric analysis by transmission electron microscopy confirms the suspected mitochondrial etiology, as the proband’s mitochondria exhibit an immature morphology with poorly developed and rare cristae. Thus, our results support the concept that sub-optimal levels of intrauterine oxygen and nutrients alter fetal mitochondrial metabolic reprogramming toward OXPHOS leading to a deficient postnatal mitochondrial energy metabolism. In conclusion, our collective studies shed light on the long-term postnatal mitochondrial pathophysiology caused by intrauterine growth restriction due to idiopathic placental insufficiency and its negative impact on the energy-demanding development of fetal and postnatal brain.

Age-related declines in vitamin D receptor (VDR) expression have been implicated in the onset of sarcopenia. The increased expression of VDR in muscle is known to increase muscle mass, whereas VDR knockout in the muscle decreases muscle mass in rats. Similar to VDR, the age-related decline in protein deacetylase sirtuin (SIRT) expression is linked to the development of sarcopenia and age-related muscle dysfunction. This study aimed to investigate whether the VDR agonist 1,25-dihydroxyvitamin D3 (1,25VD3) exerts beneficial effects on muscles through interactions with sirtuins and, if so, the underlying molecular mechanisms. 1,25VD3 treatment increases the expression of VDR, SIRT1, and SIRT3 in C2C12 myotubes. Additionally, it stimulates the differentiation of C2C12 myoblasts into myotubes. Furthermore, 1,25VD3 significantly enhanced the expression of key myogenic markers, including myosin heavy chain (MyHC) proteins (MyHC I and II), MyoD, and MyoG, and increased the phosphorylation of AMPK and AKT. Conversely, VDR knockdown in myoblasts induces myotube atrophy by downregulating SIRT1 and SIRT3 expression. Furthermore, 1,25VD3 ameliorated muscle atrophy and apoptosis induced by IFN-γ/TNF-α co-treatment to C2C12 myotube. Moreover, 1,25VD3 downregulated the increased expression of muscle atrophy-associated proteins, including FoxO3a, MAFbx, and MuRF1 in IFN-γ/TNF-α induced atrophy model. Importantly, IFN-γ/TNF-α significantly reduced the mtDNA copy number in C2C12 myotube, whereas the presence of 1,25VD3 effectively prevented this decrease. These results indirectly suggest that 1,25VD3 has the potential to develop as a therapeutic or preventive agent for age-mediated muscle atrophy by enhancing the VDR/SIRT1/SIRT3 axis and inhibiting the FoxO3-mediated atrophy pathway.