Mitochondrial Respiratory Complex Research Articles

Integrative bioinformatics analysis for identifying the mitochondrial-related gene signature associated with immune infiltration in premature ovarian insufficiency.

Premature ovarian insufficiency (POI) is a reproductive disorder characterized by the cessation of ovarian function before the age of 40. Although mitochondrial dysfunction and immune disorders are believed to contribute to ovarian damage in POI, the interplay between these factors remains understudied. In this research, transcriptomic data related to POI were obtained from the NCBI GEO database. Hub biomarkers were identified through the construction of a protein‒protein interaction (PPI) network and further validated using RT‒qPCR and Western blot. Moreover, their expression across various cell types was elucidated via single-cell RNA sequencing analysis. A comprehensive investigation of the mitochondrial and immune profiles of POI was carried out through correlation analysis. Furthermore, potential therapeutic agents were predicted utilizing the cMap database. A total of 119 mitochondria-related differentially expressed genes (MitoDEGs) were identified and shown to be significantly enriched in metabolic pathways. Among these genes, Hadhb, Cpt1a, Mrpl12, and Mrps7 were confirmed both in a POI model and in human granulosa cells (GCs), where they were found to accumulate in GCs and theca cells. Immune analysis revealed variations in macrophages, monocytes, and 15 other immune cell types between the POI and control groups. Notably, strong correlations were observed between seven hub-MitoDEGs (Hadhb, Cpt1a, Cpt2, Mrpl12, Mrps7, Mrpl51, and Eci1) and various functions, such as mitochondrial respiratory complexes, dynamics, mitophagy, mitochondrial metabolism, immune-related genes, and immunocytes. Additionally, nine potential drugs (calyculin, amodiaquine, eudesmic acid, cefotaxime, BX-912, prostratin, SCH-79797, HU-211, and pizotifen) targeting key genes were identified. Our results highlight the crosstalk between mitochondrial function and the immune response in the development of POI. The identification of MitoDEGs could lead to reliable biomarkers for the early diagnosis, monitoring, and personalized treatment of POI.

Defects in the Maturation of Mitochondrial Iron-Sulfur Proteins: Biophysical Investigation of the MMDS3 Causing Gly104Cys Variant of IBA57.

Multiple mitochondrial dysfunctions syndrome type 3 (MMDS3) is a rare autosomal recessive mitochondrial leukoencephalopathy caused by biallelic pathogenic variants in the IBA57 gene. The gene protein product, IBA57, has an unknown role in iron-sulfur (Fe-S) cluster biogenesis but is required for the maturation of mitochondrial [4Fe-4S] proteins. To better understand the role of IBA57 in MMDS3, we have investigated the impact of the pathogenic p.Gly104Cys (c.310G > T) variant on the structural and functional properties of IBA57. The Gly104Cys variant has been associated with a severe MMDS3 phenotype in both compound heterozygous and homozygous states, and defects in the activity of mitochondrial respiratory complexes and lipoic acid-dependent enzymes have been demonstrated in the affected patients. Size exclusion chromatography, also coupled to multiple angle light scattering, NMR, circular dichroism, and fluorescence spectroscopy characterization has shown that the Gly104Cys variant does not impair the conversion of the homo-dimeric [2Fe-2S]-ISCA22 complex into the hetero-dimeric IBA57-[2Fe-2S]-ISCA2 but significantly affects the stability of IBA57, in both its isolated form and in complex with ISCA2, thus providing a rationale for the severe MMDS3 phenotype associated with this variant.

P138 CORRELATION OF THE NDUFV2 RS874250 LOCUS OF THE MITOCHONDRIAL RESPIRATORY COMPLEX I NUCLEAR GENE WITH SUSCEPTIBILITY TO ESSENTIAL HYPERTENSION IN YUNNAN REGION

Background and Objective: Essential hypertension is a multifactorial disease characterized by the interaction of genetic and environmental factors, with genetic factors accounting for 30-50%. Currently, the relevant SNPs identified through genome-wide screening analysis explain only 2-3% of the blood pressure variance. It is suggested that there is a large number of undiscovered genetic variants associated with essential hypertension. The NADH-ubiquinone oxidoreductase core subunit V2 (NDUFV2) is one of the key subunits of mitochondrial respiratory Complex I, which plays an important role in oxidative stress, inflammation, and cell death, and those are associated with endothelial cell damage, vascular remodeling, and hypertension. The study aims to investigate whether the NDUFV2 rs874250 is associated with essential hypertension. Methods: In total of 1437 subjects, were Chinese-Han from Yunnan province, including 824 patients with essential hypertension (378 males and 446 females) and 613 healthy controls (240 males and 373 females). NDUFV2 rs874250 was selected for genotyping and establishing 2 genetic models: a genotypic model (GG vs GA vs AA) and a super-dominant model [GA vs (GG+AA)] for all subjects. Results: In this study, the frequency distribution of genotypes conformed to the HWE test (p>0.05). The super-dominant model was the best genetic model for the rs874250 locus of the NDUFV2 gene. Under the super-dominant model, we found that the distribution frequency of the GA genotype in the essential hypertension group was higher than that in the control group (P<0.05), and the GA genotype was a risk factor for hypertension (OR=1.30, P<0.05). Diastolic blood pressure (DBP) and mean arterial pressure were significantly higher in GA genotype carriers than in GG+GA genotype carriers after correction for sex, age, and BMI (P<0.05). Conclusions: Our study indicated that the NDUFV2 rs874250 is likely to be involved in essential hypertension, especially in diastolic pressure. We postulate that GA genotype may be a risk factor for elevated DBP, which requires further validation.

Characterization of the ubiquinone reaction cavity in mitochondrial respiratory complex I using artificial ligands

Characterization of the ubiquinone reaction cavity in mitochondrial respiratory complex I using artificial ligands

Impact of oxytosis on the cross-talk of mTORC with mitochondrial proteins in drug-resistant cancer stem cells.

By delivering the environmental inputs to transport nutrients and growth factors, Mechanistic Target of Rapamycin (mTOR) plays a significant role in the growth and metabolism of eukaryotic cells through the regulation of numerous elementary cellular processes such as autophagy, protein synthesis, via translation of mitochondrial protein transcription factor A mitochondrial, mitochondrial ribosomal proteins, and mitochondrial respiratory complexes I &V that are encoded in the nucleus with the help of translation initiation factor 4E-BP. These mitochondrial proteins are involved in cell signaling to regulate proper cell growth, proliferation, and death which are essential for tumor growth and proliferation. This suggests that tumor cells are dependent on mTORC1 for various metabolic pathways. However, this crucial regulator is activated and regulated by calcium homeostasis. Mounting evidence suggests the role of calcium ions in regulating mitochondrial enzymes and proteins. Hence, disrupting calcium homeostasis leads to calcium-dependent cell death called "Oxytosis" through hampering the expression of various mitochondrial proteins. "Oxytosis" is a novel non-apoptotic cell death characterized by glutamate cytotoxicity and ferritin degradation. The present review focuses on the crosstalk between mTORC1 and mitochondrial proteins in the cancer pathophysiology and the impact of calcium ions on disrupting mTORC1 leading to the induction of "Oxytosis."

Insights into the assembly of mitochondrial respiratory complex III

Insights into the assembly of mitochondrial respiratory complex III

The Role of Sirtuin-1 Isoforms in Regulating Mitochondrial Function.

The sirtuin-1 (SIRT1) gene contains multiple exons that usually undergo alternative splicing. The exclusion of one or more exons causes domain loss in the alternatively spliced isoforms and may change their functions. However, it is not completely established to what extent the loss of a non-catalytic domain could affect its regulatory function. Using muscle cells and SIRT1-knockout cells, we examined the function of the constitutively spliced isoform (SIRT1-v1) versus the alternatively spliced isoforms SIRT1-v2 and SIRT1-v3 that had lost part of the N-terminal region. Our data indicate that partial loss of the N-terminal domains in SIRT1-v2 and SIRT1-v3 attenuated their function. The full-length SIRT1-v1 significantly increased the oxidative phosphorylation and ATP production rate. Furthermore, SIRT1-v1 specifically upregulated the mitochondrial respiratory complex I without affecting the activity of complexes II, III, and IV. Additionally, domain loss affected the regulation of site-specific lysine acetylation in the histone H4 protein, the gene expression of respiratory complex I subunits, and the metabolic balance of oxidative phosphorylation versus glycolysis. Since alternatively spliced isoforms tend to increase with advancing age, the impact of SIRT1 isoforms on mitochondrial respiratory complexes warrants further investigation.

Regimen on Dnaja3 haploinsufficiency mediated sarcopenic obesity with imbalanced mitochondrial homeostasis and lipid metabolism.

Sarcopenic obesity is characterized by excess fat mass and diminished muscular mass/function. DNAJA3, a mitochondrial co-chaperone protein, plays a crucial role in skeletal muscle development. GMI, an immunomodulatory protein, promotes myogenic differentiation through DNAJA3 activation. This study aims to elucidate the physiological effects of muscular Dnaja3 haploinsufficiency on mitochondrial dysfunction and dysregulated lipid metabolism and to assess the efficacy of GMI in rescuing sarcopenic obesity both in vitro and in vivo. We generated mouse strain with Dnaja3 heterozygosity (HSA-Dnaja3f/+) specifically in skeletal muscle. The body weight, body composition, and locomotor activity of WT and HSA-Dnaja3f/+ mice were examined. The isolated skeletal muscles and primary myoblasts from the WT and HSA-Dnaja3f/+ mice, at young or old age, were utilized to study the molecular mechanisms, mitochondrial respiration and ROS level, mitochondrial proteomes, and serological analyses, respectively. To evaluate the therapeutic efficacy of GMI, both short-term and long-term GMI treatment were administrated intraperitoneally to the HSA-Dnaja3f/+ young (4weeks old) or adult (3months old) mice for a duration of either 1 or 6months, respectively. Muscular Dnaja3 heterozygosity resulted in impaired locomotor activity (P<0.05), reduced muscular cross-sectional area (P<0.0001), and up-regulation of lipogenesis (ACC2) and pro-inflammation (STAT3) in skeletal muscles (P<0.05). Primary myoblasts from the HSA-Dnaja3f/+ mice displayed impaired mitochondrial respiration (P<0.01) and imbalanced mitochondrial ROS levels. A systemic proteomic analysis of the purified mitochondria from the primary myoblasts was conducted to show the abnormalities in mitochondrial function and fatty acid metabolism (P<0.0001). At age of 13 to 14months, the HSA-Dnaja3f/+ mice displayed increased body fat mass (P<0.001), reduced fat-free mass (P<0.01), and impaired glucose and insulin tolerance (P<0.01). The short-term GMI treatment improved locomotor activity (P<0.01) and down-regulated the protein levels of STAT3 (P<0.05), ACC2, and mitochondrial respiratory complex III (UQCRC2) (P<0.01) via DNAJA3 activation. The long-term GMI treatment ameliorated fat mass accumulation, glucose intolerance, and systemic inflammation (AST) (P<0.05) in skeletal muscle, while enhancing thermogenesis (UCP1) (P<0.01) in eWAT. GMI treatment promoted myogenesis, enhanced oxygen consumption, and ameliorated STAT3 (P<0.01) through DNAJA3 activation (P<0.05) in vitro. Muscular Dnaja3 haploinsufficiency dysregulates mitochondrial function and lipid metabolism then leads to sarcopenic obesity. GMI emerges as a therapeutic regimen for sarcopenic obesity treatment through DNAJA3 activation.

Mitochondrial signaling pathways and their role in cancer drug resistance

Mitochondria, traditionally known as cellular powerhouses, now emerge as critical signaling centers influencing cancer progression and drug resistance. The review highlights the role that apoptotic signaling, DNA mutations, mitochondrial dynamics and metabolism play in the development of resistance mechanisms and the advancement of cancer. Targeted approaches are discussed, with an emphasis on managing mitophagy, fusion, and fission of the mitochondria to make resistant cancer cells more susceptible to traditional treatments. Additionally, metabolic reprogramming can be used to effectively target metabolic enzymes such GLUT1, HKII, PDK, and PKM2 in order to avoid resistance mechanisms. Although there are potential possibilities for therapy, the complex structure of mitochondria and their subtle role in tumor development hamper clinical translation. Novel targeted medicines are put forth, providing fresh insights on combating drug resistance in cancer. The study also emphasizes the significance of glutamine metabolism, mitochondrial respiratory complexes, and apoptotic pathways as potential targets to improve treatment effectiveness against drug-resistant cancers. Combining complementary and nanoparticle-based techniques to target mitochondria has demonstrated encouraging results in the treatment of cancer, opening doors to reduce resistance and enable individualized treatment plans catered to the unique characteristics of each patient. Suggesting innovative approaches such as drug repositioning and mitochondrial drug delivery to enhance the efficacy of mitochondria-targeting therapies, presenting a pathway for advancements in cancer treatment. This thorough investigation is a major step forward in the treatment of cancer and has the potential to influence clinical practice and enhance patient outcomes.

Oxidative Stress and Mitochondria Are Involved in Anaphylaxis and Mast Cell Degranulation: A Systematic Review.

Anaphylaxis, an allergic reaction caused by the massive release of active mediators, can lead to anaphylactic shock (AS), the most severe and potentially life-threatening form of anaphylactic reaction. Nevertheless, understanding of its pathophysiology to support new therapies still needs to be improved. We performed a systematic review, assessing the role and the complex cellular interplay of mitochondria and oxidative stress during anaphylaxis, mast cell metabolism and degranulation. After presenting the main characteristics of anaphylaxis, the oxidant/antioxidant balance and mitochondrial functions, we focused this review on the involvement of mitochondria and oxidative stress in anaphylaxis. Then, we discussed the role of oxidative stress and mitochondria following mast cell stimulation by allergens, leading to degranulation, in order to further elucidate mechanistic pathways. Finally, we considered potential therapeutic interventions implementing these findings for the treatment of anaphylaxis. Experimental studies evaluated mainly cardiomyocyte metabolism during AS. Cardiac dysfunction was associated with left ventricle mitochondrial impairment and lipid peroxidation. Studies evaluating in vitro mast cell degranulation, following Immunoglobulin E (IgE) or non-IgE stimulation, revealed that mitochondrial respiratory complex integrity and membrane potential are crucial for mast cell degranulation. Antigen stimulation raises reactive oxygen species (ROS) production from nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and mitochondria, leading to mast cell degranulation. Moreover, mast cell activation involved mitochondrial morphological changes and mitochondrial translocation to the cell surface near exocytosis sites. Interestingly, antioxidant administration reduced degranulation by lowering ROS levels. Altogether, these results highlight the crucial role of oxidative stress and mitochondria during anaphylaxis and mast cell degranulation. New therapeutics against anaphylaxis should probably target oxidative stress and mitochondria, in order to decrease anaphylaxis-induced systemic and major organ deleterious effects.

Mitochondrial respiratory complex I can be inhibited via bypassing the ubiquinone-accessing tunnel.

Mitochondrial NADH-ubiquinone oxidoreductase (complex I) couples electron transfer from NADH to ubiquinone with proton translocation in its membrane part. Structural studies have identified a long (~ 30 Å), narrow, tunnel-like cavity within the enzyme, through which ubiquinone may access a deep reaction site. Although various inhibitors are considered to block the ubiquinone reduction by occupying the tunnel's interior, this view is still debatable. We synthesized a phosphatidylcholine-quinazoline hybrid compound (PC-Qz1), in which a quinazoline-type toxophore was attached to the sn-2 acyl chain to prevent it from entering the tunnel. However, PC-Qz1 inhibited complex I and suppressed photoaffinity labeling by another quinazoline derivative, [125I]AzQ. This study provides further experimental evidence that is difficult to reconcile with the canonical ubiquinone-accessing tunnel model.

SEPTIC SHOCK: LPS TOLERANCE PROTECTS MITOCHONDRIAL BIOGENESIS AND RESPIRATION.

Mitochondrial dysfunction is a recognized feature of sepsis, characterized by ultrastructural damage, diminished oxidative phosphorylation, and depletion of mitochondrial antioxidant capacity observed in deceased septic patients. LPS tolerance induces a controlled response to sepsis. This study aimed to evaluate the function of tolerant mitochondria after cecal ligation and puncture (CLP)-induced sepsis. Mytochondrial oxygen consumption was determined using polarography. Extraction and quantification of RNA for the expression of Tfam, Nrf-1, and Ppargc-1α, and respiratory complex activity were measured. CLP-tolerant animals presented preserved respiratory rates of S3 and S4 and a ratio of respiratory control (RCR) compared to CLP-nontolerant animals with reduced oxidative phosphorylation and increased uncoupled respiration. Complex I Vmax was reduced in septic animals; however, CLP animals sustained normal Vmax. Mitochondrial biogenesis was preserved in CLP-tolerant animals compared to the CLP-nontolerant group, likely due to increased TFAM expression. LPS tolerance protected septic animals from mitochondrial dysfunction, favoring mitochondrial biogenesis and preserving mitochondrial respiration and respiratory complex I activity.

Decreasing Intracellular Entropy by Increasing Mitochondrial Efficiency and Reducing ROS Formation-The Effect on the Ageing Process and Age-Related Damage.

A hypothesis is presented to explain how the ageing process might be influenced by optimizing mitochondrial efficiency to reduce intracellular entropy. Research-based quantifications of entropy are scarce. Non-equilibrium metabolic reactions and compartmentalization were found to contribute most to lowering entropy in the cells. Like the cells, mitochondria are thermodynamically open systems exchanging matter and energy with their surroundings-the rest of the cell. Based on the calculations from cancer cells, glycolysis was reported to produce less entropy than mitochondrial oxidative phosphorylation. However, these estimations depended on the CO2 concentration so that at slightly increased CO2, it was oxidative phosphorylation that produced less entropy. Also, the thermodynamic efficiency of mitochondrial respiratory complexes varies depending on the respiratory state and oxidant/antioxidant balance. Therefore, in spite of long-standing theoretical and practical efforts, more measurements, also in isolated mitochondria, with intact and suboptimal respiration, are needed to resolve the issue. Entropy increases in ageing while mitochondrial efficiency of energy conversion, quality control, and turnover mechanisms deteriorate. Optimally functioning mitochondria are necessary to meet energy demands for cellular defence and repair processes to attenuate ageing. The intuitive approach of simply supplying more metabolic fuels (more nutrients) often has the opposite effect, namely a decrease in energy production in the case of nutrient overload. Excessive nutrient intake and obesity accelerate ageing, while calorie restriction without malnutrition can prolong life. Balanced nutrient intake adapted to needs/activity-based high ATP requirement increases mitochondrial respiratory efficiency and leads to multiple alterations in gene expression and metabolic adaptations. Therefore, rather than overfeeding, it is necessary to fine-tune energy production by optimizing mitochondrial function and reducing oxidative stress; the evidence is discussed in this paper.

RNA: De-silencing to the rescue

The fate of transcribed RNA dictates cellular function. A new study finds that mutations in specific RNA processing machinery genes result in de-silencing of a transcript encoding a subunit of the mitochondrial electron transport chain and rescue of a mitochondrial respiratory complex I defect.

Effects of a Ketogenic Diet on the Assessment of Biochemical and Clinical Parameters in Duchenne Muscular Dystrophy: A Preclinical Investigation.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive skeletal muscle degeneration and systemic effects, including the central nervous system (CNS). This study aimed to assess the impact of a 14-day ketogenic diet (DCet) on biochemical and clinical parameters in a DMD mouse model. Young adult mice (50 days old) were fed DCet, while control groups received a standard diet. On the 14th day, memory and behavior tests were conducted, followed by biochemical evaluations of oxidative stress, inflammatory biomarkers, body weight, feed intake, and brain-derived neurotrophic factor (BDNF) levels. mdx + DCet mice showed reduced mass (0.2 g ± 2.49) and improved memory retention (p < 0.05) compared to controls. Oxidative damage in muscle tissue and CNS decreased, along with a significant cytokine level reduction (p <0.05). The protocol led to an increase in hippocampal BDNF and mitochondrial respiratory complex activity in muscle tissue and the central nervous system (CNS), while also decreasing creatine kinase activity only in the striatum. Overall, a 14-day DCet showed protective effects by improving spatial learning and memory through reductions in oxidative stress and immune response, as well as increases in BDNF levels, consistent with our study's findings.

Comprehensive overview of how to fade into succinate dehydrogenase dysregulation in cancer cells by naringenin-loaded chitosan nanoparticles.

Mitochondrial respiration complexes play a crucial function. As a result, dysfunction or change is intimately associated with many different diseases, among them cancer. The epigenetic, evolutionary, and metabolic effects of mitochondrial complex IΙ are the primary concerns of our review. Provides novel insight intothe vital role of naringenin (NAR) as an intriguing flavonoid phytochemical in cancer treatment. NAR is a significant phytochemical that is a member of the flavanone group of polyphenols and is mostly present in citrus fruits, such as grapefruits, as well as other fruits and vegetables, like tomatoes and cherries, as well as foods produced from medicinal herbs. The evidence that is now available indicates that NAR, an herbal remedy, has significant pharmacological qualities and anti-cancer effects. Through a variety of mechanisms, including the induction of apoptosis, cell cycle arrest, restriction of angiogenesis, and modulation of several signaling pathways, NAR prevents the growth of cancer. However, the hydrophobic and crystalline structure of NAR is primarily responsible for its instability, limited oral bioavailability, and water solubility. Furthermore, there is no targeting and a high rate of breakdown in an acidic environment. These shortcomings are barriers to its efficient medical application. Improvement targeting NAR to mitochondrial complex ΙΙ by loading it on chitosan nanoparticles is a promising strategy.

10-(6-Plastoquinonyl) decyltriphenylphosphonium imparts anti-colitogenic protection through recovery of mitochondrial dysfunction in ulcerated murine colon: Implications in ulcerative colitis

AimsTo elucidate the impact of 10-(6-plastoquinonyl) decyltriphenylphosphonium (SkQ1) as an anti-colitogenic agent for maintenance of colon epithelial tract in ulcerated mice through recovery of mitochondrial dysfunction and mitochondrial stress by virtue of its free radical scavenging properties. Main methodsDSS induced ulcerated BALB/c mice were treated with SkQ1 for 14 days @ 30 nmol/kg/body wt./day/mice. Post-treatment, isolated colonic mitochondria were utilized for spectrophotometric and spectrofluorometric biochemical analysis of various mitochondrial functional variables including individual mitochondrial respiratory enzyme complexes. Confocal microscopy was utilized for measuring mitochondrial membrane potential in vivo. ELISA technique was adapted for measuring colonic nitrite and 3–nitrotyrosine (3-NT) content. Finally in vitro cell line study was carried out to substantiate in vivo findings and elucidate the involvement of free radicals in UC using antioxidant/free radical scavenging regimen. Key findingsTreatment with SkQ1 in vivo reduced histopathological severity of colitis, induced recovery of mitochondrial respiratory complex activities and associated functional variables, improved oxidative stress indices and normalized mitochondrial cardiolipin content. Importantly, SkQ1 lowered nitrite concentration and 3–nitrotyrosine formation in vivo. In vitro SkQ1 restored mitochondrial functions wherein the efficacy of SkQ1 proved equal or better compared to SOD and DMSO indicating predominant involvement of O2− and OH in UC. However, NO and ONOO− also seemed to play a secondary role as MEG and L-NAME provided lesser protection as compared to SOD and DMSO. SignificanceSkQ1 can be considered as a potent anti-colitogenic agent by virtue of its free radical scavenging properties in treating UC.

Identification of a family of species-selective complex I inhibitors as potential anthelmintics

Soil-transmitted helminths (STHs) are major pathogens infecting over a billion people. There are few classes of anthelmintics and there is an urgent need for new drugs. Many STHs use an unusual form of anaerobic metabolism to survive the hypoxic conditions of the host gut. This requires rhodoquinone (RQ), a quinone electron carrier. RQ is not made or used by vertebrate hosts making it an excellent therapeutic target. Here we screen 480 structural families of natural products to find compounds that kill Caenorhabditis elegans specifically when they require RQ-dependent metabolism. We identify several classes of compounds including a family of species-selective inhibitors of mitochondrial respiratory complex I. These identified complex I inhibitors have a benzimidazole core and we determine key structural requirements for activity by screening 1,280 related compounds. Finally, we show several of these compounds kill adult STHs. We suggest these species-selective complex I inhibitors are potential anthelmintics.

Multiomics analysis identifies oxidative phosphorylation as a cancer vulnerability arising from myristoylation inhibition

BackgroundIn humans, two ubiquitously expressed N-myristoyltransferases, NMT1 and NMT2, catalyze myristate transfer to proteins to facilitate membrane targeting and signaling. We investigated the expression of NMTs in numerous cancers and found that NMT2 levels are dysregulated by epigenetic suppression, particularly so in hematologic malignancies. This suggests that pharmacological inhibition of the remaining NMT1 could allow for the selective killing of these cells, sparing normal cells with both NMTs.Methods and resultsTranscriptomic analysis of 1200 NMT inhibitor (NMTI)-treated cancer cell lines revealed that NMTI sensitivity relates not only to NMT2 loss or NMT1 dependency, but also correlates with a myristoylation inhibition sensitivity signature comprising 54 genes (MISS-54) enriched in hematologic cancers as well as testis, brain, lung, ovary, and colon cancers. Because non-myristoylated proteins are degraded by a glycine-specific N-degron, differential proteomics revealed the major impact of abrogating NMT1 genetically using CRISPR/Cas9 in cancer cells was surprisingly to reduce mitochondrial respiratory complex I proteins rather than cell signaling proteins, some of which were also reduced, albeit to a lesser extent. Cancer cell treatments with the first-in-class NMTI PCLX-001 (zelenirstat), which is undergoing human phase 1/2a trials in advanced lymphoma and solid tumors, recapitulated these effects. The most downregulated myristoylated mitochondrial protein was NDUFAF4, a complex I assembly factor. Knockout of NDUFAF4 or in vitro cell treatment with zelenirstat resulted in loss of complex I, oxidative phosphorylation and respiration, which impacted metabolomes.ConclusionsTargeting of both, oxidative phosphorylation and cell signaling partly explains the lethal effects of zelenirstat in select cancer types. While the prognostic value of the sensitivity score MISS-54 remains to be validated in patients, our findings continue to warrant the clinical development of zelenirstat as cancer treatment.

A novel inhibitor of the mitochondrial respiratory complex I with uncoupling properties exerts potent antitumor activity

Cancer cells are highly dependent on bioenergetic processes to support their growth and survival. Disruption of metabolic pathways, particularly by targeting the mitochondrial electron transport chain complexes (ETC-I to V) has become an attractive therapeutic strategy. As a result, the search for clinically effective new respiratory chain inhibitors with minimized adverse effects is a major goal. Here, we characterize a new OXPHOS inhibitor compound called MS-L6, which behaves as an inhibitor of ETC-I, combining inhibition of NADH oxidation and uncoupling effect. MS-L6 is effective on both intact and sub-mitochondrial particles, indicating that its efficacy does not depend on its accumulation within the mitochondria. MS-L6 reduces ATP synthesis and induces a metabolic shift with increased glucose consumption and lactate production in cancer cell lines. MS-L6 either dose-dependently inhibits cell proliferation or induces cell death in a variety of cancer cell lines, including B-cell and T-cell lymphomas as well as pediatric sarcoma. Ectopic expression of Saccharomyces cerevisiae NADH dehydrogenase (NDI-1) partially restores the viability of B-lymphoma cells treated with MS-L6, demonstrating that the inhibition of NADH oxidation is functionally linked to its cytotoxic effect. Furthermore, MS-L6 administration induces robust inhibition of lymphoma tumor growth in two murine xenograft models without toxicity. Thus, our data present MS-L6 as an inhibitor of OXPHOS, with a dual mechanism of action on the respiratory chain and with potent antitumor properties in preclinical models, positioning it as the pioneering member of a promising drug class to be evaluated for cancer therapy.MS-L6 exerts dual mitochondrial effects: ETC-I inhibition and uncoupling of OXPHOS. In cancer cells, MS-L6 inhibited ETC-I at least 5 times more than in isolated rat hepatocytes. These mitochondrial effects lead to energy collapse in cancer cells, resulting in proliferation arrest and cell death. In contrast, hepatocytes which completely and rapidly inactivated this molecule, restored their energy status and survived exposure to MS-L6 without apparent toxicity.