Ubiquinone (UQ), the only known electron carrier in the mammalian electron transport chain (ETC), preferentially delivers electrons to the terminal electron acceptor oxygen (O2). In hypoxia, ubiquinol (UQH2) diverts these electrons onto fumarate instead. Here, we identify rhodoquinone (RQ), an electron carrier detected in mitochondria purified from certain mouse and human tissues that preferentially delivers electrons to fumarate through the reversal of succinate dehydrogenase, independent of environmental O2 levels. The RQ/fumarate ETC is strictly present in vivo and is undetectable in cultured mammalian cells. Using genetic and pharmacologic tools that reprogram the ETC from the UQ/O2 to the RQ/fumarate pathway, we establish that these distinct ETCs support unique programs of mitochondrial function and that RQ confers protection upon hypoxia exposure in vitro and in vivo. Thus, in discovering the presence of RQ in mammals, we unveil a tractable therapeutic strategy that exploits flexibility in the ETC to ameliorate hypoxia-related conditions.

• Klíčová slova
• electron transport chain, hypoxia, ischemia, metabolism, mitochondria, rhodoquinone,
• MeSH
• elektrony MeSH
• fumaráty metabolismus   MeSH
• hypoxie metabolismus   MeSH
• kyslík metabolismus   MeSH
• lidé MeSH
• mitochondrie * metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• sukcinátdehydrogenasa metabolismus   MeSH
• transport elektronů MeSH
• ubichinon * metabolismus   analogy a deriváty   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fumaráty MeSH
• kyslík MeSH
• rhodoquinone MeSH Prohlížeč
• sukcinátdehydrogenasa MeSH
• ubichinon * MeSH

Mitochondria (mt) represent the vital hub of the molecular physiology of the cell, being decision-makers in cell life/death and information signaling, including major redox regulations and redox signaling. Now we review recent advances in understanding mitochondrial redox homeostasis, including superoxide sources and H2O2 consumers, i.e., antioxidant mechanisms, as well as exemplar situations of physiological redox signaling, including the intramitochondrial one and mt-to-cytosol redox signals, which may be classified as acute and long-term signals. This review exemplifies the acute redox signals in hypoxic cell adaptation and upon insulin secretion in pancreatic beta-cells. We also show how metabolic changes under these circumstances are linked to mitochondrial cristae narrowing at higher intensity of ATP synthesis. Also, we will discuss major redox buffers, namely the peroxiredoxin system, which may also promote redox signaling. We will point out that pathological thresholds exist, specific for each cell type, above which the superoxide sources exceed regular antioxidant capacity and the concomitant harmful processes of oxidative stress subsequently initiate etiology of numerous diseases. The redox signaling may be impaired when sunk in such excessive pro-oxidative state.

• MeSH
• antioxidancia metabolismus   MeSH
• beta-buňky metabolismus   MeSH
• lidé MeSH
• mitochondrie * metabolismus   MeSH
• oxidace-redukce * MeSH
• oxidační stres fyziologie   MeSH
• signální transdukce fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• antioxidancia MeSH

BACKGROUND: Fast adaptation of glycolytic and mitochondrial energy pathways to changes in the tumour microenvironment is a hallmark of cancer. Purely glycolytic ρ0 tumour cells do not form primary tumours unless they acquire healthy mitochondria from their micro-environment. Here we explored the effects of severely compromised respiration on the metastatic capability of 4T1 mouse breast cancer cells. METHODS: 4T1 cell lines with different levels of respiratory capacity were generated; the Seahorse extracellular flux analyser was used to evaluate oxygen consumption rates, fluorescent confocal microscopy to assess the number of SYBR gold-stained mitochondrial DNA nucleoids, and the presence of the ATP5B protein in the cytoplasm and fluorescent in situ nuclear hybridization was used to establish ploidy. MinION nanopore RNA sequence analysis was used to compare mitochondrial DNA transcription between cell lines. Orthotopic injection was used to determine the ability of cells to metastasize to the lungs of female Balb/c mice. RESULTS: OXPHOS-deficient ATP5B-KO3.1 cells did not generate primary tumours. Severely OXPHOS compromised ρ0D5 cells generated both primary tumours and lung metastases. Cells generated from lung metastasis of both OXPHOS-competent and OXPHOS-compromised cells formed primary tumours but no metastases when re-injected into mice. OXPHOS-compromised cells significantly increased their mtDNA content, but this did not result in increased OXPHOS capacity, which was not due to decreased mtDNA transcription. Gene set enrichment analysis suggests that certain cells derived from lung metastases downregulate their epithelial-to-mesenchymal related pathways. CONCLUSION: In summary, OXPHOS is required for tumorigenesis in this orthotopic mouse breast cancer model but even very low levels of OXPHOS are sufficient to generate both primary tumours and lung metastases.

• Klíčová slova
• breast cancer, glycolysis, intercellular mitochondrial transport, metastasis, orthotopic mouse model, oxidative phosphorylation,
• Publikační typ
• časopisecké články MeSH

Significance: Mitochondrial (mt) reticulum network in the cell possesses amazing ultramorphology of parallel lamellar cristae, formed by the invaginated inner mitochondrial membrane. Its non-invaginated part, the inner boundary membrane (IBM) forms a cylindrical sandwich with the outer mitochondrial membrane (OMM). Crista membranes (CMs) meet IBM at crista junctions (CJs) of mt cristae organizing system (MICOS) complexes connected to OMM sorting and assembly machinery (SAM). Cristae dimensions, shape, and CJs have characteristic patterns for different metabolic regimes, physiological and pathological situations. Recent Advances: Cristae-shaping proteins were characterized, namely rows of ATP-synthase dimers forming the crista lamella edges, MICOS subunits, optic atrophy 1 (OPA1) isoforms and mitochondrial genome maintenance 1 (MGM1) filaments, prohibitins, and others. Detailed cristae ultramorphology changes were imaged by focused-ion beam/scanning electron microscopy. Dynamics of crista lamellae and mobile CJs were demonstrated by nanoscopy in living cells. With tBID-induced apoptosis a single entirely fused cristae reticulum was observed in a mitochondrial spheroid. Critical Issues: The mobility and composition of MICOS, OPA1, and ATP-synthase dimeric rows regulated by post-translational modifications might be exclusively responsible for cristae morphology changes, but ion fluxes across CM and resulting osmotic forces might be also involved. Inevitably, cristae ultramorphology should reflect also mitochondrial redox homeostasis, but details are unknown. Disordered cristae typically reflect higher superoxide formation. Future Directions: To link redox homeostasis to cristae ultramorphology and define markers, recent progress will help in uncovering mechanisms involved in proton-coupled electron transfer via the respiratory chain and in regulation of cristae architecture, leading to structural determination of superoxide formation sites and cristae ultramorphology changes in diseases. Antioxid. Redox Signal. 39, 635-683.

• Klíčová slova
• ATP-synthase dimeric rows, MICOS, OPA1, mitochondrial cristae, mitochondrial superoxide formation, respiratory chain supercomplexes,
• MeSH
• adenosintrifosfát metabolismus   MeSH
• homeostáza MeSH
• mitochondriální membrány * metabolismus   MeSH
• mitochondriální proteiny metabolismus   MeSH
• oxidace-redukce MeSH
• superoxidy * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• adenosintrifosfát MeSH
• mitochondriální proteiny MeSH
• superoxidy * MeSH

Mammalian genes were long thought to be constrained within somatic cells in most cell types. This concept was challenged recently when cellular organelles including mitochondria were shown to move between mammalian cells in culture via cytoplasmic bridges. Recent research in animals indicates transfer of mitochondria in cancer and during lung injury in vivo, with considerable functional consequences. Since these pioneering discoveries, many studies have confirmed horizontal mitochondrial transfer (HMT) in vivo, and its functional characteristics and consequences have been described. Additional support for this phenomenon has come from phylogenetic studies. Apparently, mitochondrial trafficking between cells occurs more frequently than previously thought and contributes to diverse processes including bioenergetic crosstalk and homeostasis, disease treatment and recovery, and development of resistance to cancer therapy. Here we highlight current knowledge of HMT between cells, focusing primarily on in vivo systems, and contend that this process is not only (patho)physiologically relevant, but also can be exploited for the design of novel therapeutic approaches.

• MeSH
• energetický metabolismus MeSH
• fylogeneze MeSH
• mitochondrie * metabolismus   MeSH
• nádory * genetika   metabolismus   MeSH
• savci MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• komentáře MeSH
• práce podpořená grantem MeSH

Targeting tumor metabolism for cancer therapy is an old strategy. In fact, historically the first effective cancer therapeutics were directed at nucleotide metabolism. The spectrum of metabolic drugs considered in cancer increases rapidly - clinical trials are in progress for agents directed at glycolysis, oxidative phosphorylation, glutaminolysis and several others. These pathways are essential for cancer cell proliferation and redox homeostasis, but are also required, to various degrees, in other cell types present in the tumor microenvironment, including immune cells, endothelial cells and fibroblasts. How metabolism-targeted treatments impact these tumor-associated cell types is not fully understood, even though their response may co-determine the overall effectivity of therapy. Indeed, the metabolic dependencies of stromal cells have been overlooked for a long time. Therefore, it is important that metabolic therapy is considered in the context of tumor microenvironment, as understanding the metabolic vulnerabilities of both cancer and stromal cells can guide new treatment concepts and help better understand treatment resistance. In this review we discuss recent findings covering the impact of metabolic interventions on cellular components of the tumor microenvironment and their implications for metabolic cancer therapy.

• Klíčová slova
• cancer, endothelial cells, fatty acid metabolism, glycolysis, metabolism, nucleotide metabolism, oxidative phoshorylation, tumor micro environment (TME),
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Interleukin 6 (IL-6) belongs to a broad class of cytokines involved in the regulation of various homeostatic and pathological processes. These activities range from regulating embryonic development, wound healing and ageing, inflammation, and immunity, including COVID-19. In this review, we summarise the role of IL-6 signalling pathways in cancer biology, with particular emphasis on cancer cell invasiveness and metastasis formation. Targeting principal components of IL-6 signalling (e.g., IL-6Rs, gp130, STAT3, NF-κB) is an intensively studied approach in preclinical cancer research. It is of significant translational potential; numerous studies strongly imply the remarkable potential of IL-6 signalling inhibitors, especially in metastasis suppression.

• Klíčová slova
• IL-6, cancer, metastasis,
• MeSH
• antitumorózní látky * terapeutické užití   MeSH
• interleukin-6 metabolismus   MeSH
• lidé MeSH
• nádory * farmakoterapie   MeSH
• signální transdukce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• antitumorózní látky * MeSH
• IL6 protein, human MeSH Prohlížeč
• interleukin-6 MeSH

Mitochondria are organelles essential for tumor cell proliferation and metastasis. Although their main cellular function, generation of energy in the form of ATP is dispensable for cancer cells, their capability to drive their adaptation to stress originating from tumor microenvironment makes them a plausible therapeutic target. Recent research has revealed that cancer cells with damaged oxidative phosphorylation import healthy (functional) mitochondria from surrounding stromal cells to drive pyrimidine synthesis and cell proliferation. Furthermore, it has been shown that energetically competent mitochondria are fundamental for tumor cell migration, invasion and metastasis. The spatial positioning and transport of mitochondria involves Miro proteins from a subfamily of small GTPases, localized in outer mitochondrial membrane. Miro proteins are involved in the structure of the MICOS complex, connecting outer and inner-mitochondrial membrane; in mitochondria-ER communication; Ca2+ metabolism; and in the recycling of damaged organelles via mitophagy. The most important role of Miro is regulation of mitochondrial movement and distribution within (and between) cells, acting as an adaptor linking organelles to cytoskeleton-associated motor proteins. In this review, we discuss the function of Miro proteins in various modes of intercellular mitochondrial transfer, emphasizing the structure and dynamics of tunneling nanotubes, the most common transfer modality. We summarize the evidence for and propose possible roles of Miro proteins in nanotube-mediated transfer as well as in cancer cell migration and metastasis, both processes being tightly connected to cytoskeleton-driven mitochondrial movement and positioning.

• Klíčová slova
• Miro, cancer, intercellular transfer, metastasis, migration, mitochondria, respiration,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH