@article{MTMT:34758725, title = {Complex I activity in hypoxia: implications for oncometabolism}, url = {https://m2.mtmt.hu/api/publication/34758725}, author = {Chinopoulos, Christos}, doi = {10.1042/BST20230189}, journal-iso = {BIOCHEM SOC T}, journal = {BIOCHEMICAL SOCIETY TRANSACTIONS}, volume = {52}, unique-id = {34758725}, issn = {0300-5127}, abstract = {Certain cancer cells within solid tumors experience hypoxia, rendering them incapable of oxidative phosphorylation (OXPHOS). Despite this oxygen deficiency, these cells exhibit biochemical pathway activity that relies on NAD+. This mini-review scrutinizes the persistent, residual Complex I activity that oxidizes NADH in the absence of oxygen as the electron acceptor. The resulting NAD+ assumes a pivotal role in fueling the α-ketoglutarate dehydrogenase complex, a critical component in the oxidative decarboxylation branch of glutaminolysis — a hallmark oncometabolic pathway. The proposition is that through glutamine catabolism, high-energy phosphate intermediates are produced via substrate-level phosphorylation in the mitochondrial matrix substantiated by succinyl-CoA ligase, partially compensating for an OXPHOS deficiency. These insights provide a rationale for exploring Complex I inhibitors in cancer treatment, even when OXPHOS functionality is already compromised.}, year = {2024}, eissn = {1470-8752}, orcid-numbers = {Chinopoulos, Christos/0000-0003-0183-4149} } @article{MTMT:34518788, title = {Residual Complex I activity and amphidirectional Complex II operation support glutamate catabolism through mtSLP in anoxia}, url = {https://m2.mtmt.hu/api/publication/34518788}, author = {Ravasz, Dóra and Bui, Dávid and Nazarian, Sara and Pallag, Gergely and Karnok, Noémi and Roberts, Jennie and Marzullo, Bryan P. and Tennant, Daniel A. and Greenwood, Bennett and Kitayev, Alex and Hill, Collin and Komlódi, Tímea and Doerrier, Carolina and Cunatova, Kristyna and Fernandez-Vizarra, Erika and Gnaiger, Erich and Kiebish, Michael A. and Raska, Alexandra and Kolev, Kraszimir Nikolaev and Czumbel, Bence and Narain, Niven R. and Seyfried, Thomas N. and Chinopoulos, Christos}, doi = {10.1038/s41598-024-51365-4}, journal-iso = {SCI REP}, journal = {SCIENTIFIC REPORTS}, volume = {14}, unique-id = {34518788}, issn = {2045-2322}, abstract = {Anoxia halts oxidative phosphorylation (OXPHOS) causing an accumulation of reduced compounds in the mitochondrial matrix which impedes dehydrogenases. By simultaneously measuring oxygen concentration, NADH autofluorescence, mitochondrial membrane potential and ubiquinone reduction extent in isolated mitochondria in real-time, we demonstrate that Complex I utilized endogenous quinones to oxidize NADH under acute anoxia. 13 C metabolic tracing or untargeted analysis of metabolites extracted during anoxia in the presence or absence of site-specific inhibitors of the electron transfer system showed that NAD + regenerated by Complex I is reduced by the 2-oxoglutarate dehydrogenase Complex yielding succinyl-CoA supporting mitochondrial substrate-level phosphorylation (mtSLP), releasing succinate. Complex II operated amphidirectionally during the anoxic event, providing quinones to Complex I and reducing fumarate to succinate. Our results highlight the importance of quinone provision to Complex I oxidizing NADH maintaining glutamate catabolism and mtSLP in the absence of OXPHOS.}, year = {2024}, eissn = {2045-2322}, orcid-numbers = {Ravasz, Dóra/0000-0002-0510-3282; Bui, Dávid/0000-0003-3726-2031; Pallag, Gergely/0000-0003-4093-162X; Karnok, Noémi/0000-0002-1832-368X; Komlódi, Tímea/0000-0001-9876-1411; Raska, Alexandra/0000-0002-5348-2264; Kolev, Kraszimir Nikolaev/0000-0002-5612-004X; Chinopoulos, Christos/0000-0003-0183-4149} } @{MTMT:34093022, title = {Cancer}, url = {https://m2.mtmt.hu/api/publication/34093022}, author = {Noakes, T.D. and Kalamian, M. and Seyfried, T.N. and Mukherjee, P. and D’Agostino, D.P. and Arismendi-Morillo, G. and Chinopoulos, Christos and Tettenborn, M. and Winters, N.}, booktitle = {Ketogenic: The Science of Therapeutic Carbohydrate Restriction in Human Health}, doi = {10.1016/B978-0-12-821617-0.00012-7}, unique-id = {34093022}, abstract = {Since the discovery of DNA, the metabolic theory of cancer has been sidelined for genetic research. Yet cancer continues to rise. New research recaptures mitochondria as the driver, while upregulation of oncogenes and tumour suppressor mutations are recognised as downstream of the damage to oxidative phosphorylation (OxPhos). Despite the prevalence of the somatic (genetic) mutation theory, there are numerous inconsistencies. In contrast, it appears that all cancers are characterised by dysfunctional mitochondria. Cancer pre-1960 was a rare disease, all of which has changed as diets have. Press-pulse therapy and ketogenic diets (KD) have proven effective therapies, due to cancers’ selective metabolism of glucose and glutamine (Warburg effect), in combination with the non-fermentability of ketones. Some dietary aspects are individualised to the patient and cancer, but follow this general protocol. Fasting induces additional selective stress to cancers. With cancer genetic research stagnating and metabolic approaches showing promise, this perspective offers a new path forward. © 2023 Elsevier Inc. All rights reserved.}, keywords = {KETO; mitochondrial dysfunction; Glycolysis; lifestyle modification; Warburg effect; Oxidative phosphorylation (OXPHOS); low-carbohydrate; ketogenic; Carbohydrate restriction; Glutaminolysis; Somatic mutation theory (SMT); high-fat (LCHF); metabolic theory of cancer (MTC); press-pulse therapy; Q effect; therapeutic carbohydrate reduction; therapeutic carbohydrate restriction}, year = {2023}, pages = {307-362}, orcid-numbers = {Chinopoulos, Christos/0000-0003-0183-4149} } @article{MTMT:34062226, title = {Viability of HepG2 and MCF-7 cells is not correlated with mitochondrial bioenergetics}, url = {https://m2.mtmt.hu/api/publication/34062226}, author = {Dóczi, Judit and Karnok, Noémi and Bui, Dávid and Azarov, Victoria and Pallag, Gergely and Nazarian, Sara and Czumbel, Bence and Seyfried, Thomas N. and Chinopoulos, Christos}, doi = {10.1038/s41598-023-37677-x}, journal-iso = {SCI REP}, journal = {SCIENTIFIC REPORTS}, volume = {13}, unique-id = {34062226}, issn = {2045-2322}, abstract = {Alterations in metabolism are a hallmark of cancer. It is unclear if oxidative phosphorylation (OXPHOS) is necessary for tumour cell survival. In this study, we investigated the effects of severe hypoxia, site-specific inhibition of respiratory chain (RC) components, and uncouplers on necrotic and apoptotic markers in 2D-cultured HepG2 and MCF-7 tumour cells. Comparable respiratory complex activities were observed in both cell lines. However, HepG2 cells exhibited significantly higher oxygen consumption rates (OCR) and respiratory capacity than MCF-7 cells. Significant non-mitochondrial OCR was observed in MCF-7 cells, which was insensitive to acute combined inhibition of complexes I and III. Pre-treatment of either cell line with RC inhibitors for 24–72 h resulted in the complete abolition of respective complex activities and OCRs. This was accompanied by a time-dependent decrease in citrate synthase activity, suggesting mitophagy. High-content automated microscopy recordings revealed that the viability of HepG2 cells was mostly unaffected by any pharmacological treatment or severe hypoxia. In contrast, the viability of MCF-7 cells was strongly affected by inhibition of complex IV (CIV) or complex V (CV), severe hypoxia, and uncoupling. However, it was only moderately affected by inhibition of complexes I, II, and III. Cell death in MCF-7 cells induced by inhibition of complexes II, III, and IV was partially abrogated by aspartate. These findings indicate that OXPHOS activity and viability are not correlated in these cell lines, suggesting that the connection between OXPHOS and cancer cell survival is dependent on the specific cell type and conditions.}, year = {2023}, eissn = {2045-2322}, orcid-numbers = {Dóczi, Judit/0000-0002-5797-5074; Karnok, Noémi/0000-0002-1832-368X; Bui, Dávid/0000-0003-3726-2031; Pallag, Gergely/0000-0003-4093-162X; Chinopoulos, Christos/0000-0003-0183-4149} } @CONFERENCE{MTMT:34010234, title = {Selective induction of Krebs cycle enzyme subunits in the parahippocampal cortex of suicide victims}, url = {https://m2.mtmt.hu/api/publication/34010234}, author = {Dóra, Fanni and Tamara, Hajdu and Dobolyiné Renner, Éva and Palkovits, Miklós and Chinopoulos, Christos and Dobolyi, Árpád}, booktitle = {Joint Neuroscience Meeting of the Hungarian Neuroscience Society (MITT) & the Austrian Neuroscience Association (ANA)}, unique-id = {34010234}, abstract = {Altered functional connectivity in human cortical networks has been reported in psychiatric disorders. One of these networks, the default mode network (DMN) is critical in mood disorders. Abnormal activity in the parahippocampal cortex (PHC), a moderating hub of the ventral DMN, has been reported in depressed patients and suicide attempters. Alterations in neuronal mitochondrial function may contribute to depression and suicidal behavior, however, little is known about the underlying molecular level changes in relevant structures including the PHC. Therefore, we addressed the protein level alterations of tricarboxylic acid cycle (Krebs cycle) enzyme subunits in the PHC of suicide victims by reverse phase protein array (RPPA). Postmortem human brain samples were collected from 13 control and 11 suicide individuals. The entorhinal cortex (EC), adjacent to the PHC, was selected to serve as a control brain region. RPPA analysis revealed that the protein levels of DLD, OGDH, SDHB, SUCLA2 and SUCLG2 were significantly induced in the PHC but not in the EC. Subsequently, qRT-PCR was used to examine if mRNA level changes are behind altered protein levels associated with suicide. The identified expressional changes suggest the selective upregulation of major Krebs cycle enzyme subunits belonging to glutaminolysis in the PHC suggesting the potentiation and a prominent role of this process in the pathophysiology of suicidal behavior.}, year = {2023}, orcid-numbers = {Dóra, Fanni/0000-0001-8301-8203; Palkovits, Miklós/0000-0003-0578-0387; Chinopoulos, Christos/0000-0003-0183-4149; Dobolyi, Árpád/0000-0003-0397-2991} } @article{MTMT:33101302, title = {Metabolic management of microenvironment acidity in glioblastoma}, url = {https://m2.mtmt.hu/api/publication/33101302}, author = {Seyfried, Thomas N. and Arismendi-Morillo, Gabriel and Zuccoli, Giulio and Lee, Derek C. and Duraj, Tomas and Elsakka, Ahmed M. and Maroon, Joseph C. and Mukherjee, Purna and Ta, Linh and Shelton, Laura and D'Agostino, Dominic and Kiebish, Michael and Chinopoulos, Christos}, doi = {10.3389/fonc.2022.968351}, journal-iso = {FRONT ONCOL}, journal = {FRONTIERS IN ONCOLOGY}, volume = {12}, unique-id = {33101302}, issn = {2234-943X}, abstract = {Glioblastoma (GBM), similar to most cancers, is dependent on fermentation metabolism for the synthesis of biomass and energy (ATP) regardless of the cellular or genetic heterogeneity seen within the tumor. The transition from respiration to fermentation arises from the documented defects in the number, the structure, and the function of mitochondria and mitochondrial-associated membranes in GBM tissue. Glucose and glutamine are the major fermentable fuels that drive GBM growth. The major waste products of GBM cell fermentation (lactic acid, glutamic acid, and succinic acid) will acidify the microenvironment and are largely responsible for drug resistance, enhanced invasion, immunosuppression, and metastasis. Besides surgical debulking, therapies used for GBM management (radiation, chemotherapy, and steroids) enhance microenvironment acidification and, although often providing a time-limited disease control, will thus favor tumor recurrence and complications. The simultaneous restriction of glucose and glutamine, while elevating non-fermentable, anti-inflammatory ketone bodies, can help restore the pH balance of the microenvironment while, at the same time, providing a non-toxic therapeutic strategy for killing most of the neoplastic cells.}, keywords = {glutamate; CANCER-CELLS; LACTATE; FERMENTATION; mitochondrial dysfunction; Glycolysis; OXIDATIVE-PHOSPHORYLATION; LONG-TERM SURVIVAL; Ketogenic diet; Ketogenic diet; adjuvant chemoradiotherapy; SUCCINATE; Glutaminolysis; KETONE-BODIES; ADVERSE PROGNOSTIC IMPACT; A TRANSFERASE-ACTIVITY}, year = {2022}, eissn = {2234-943X}, orcid-numbers = {Chinopoulos, Christos/0000-0003-0183-4149} } @article{MTMT:33070137, title = {Reverse and Forward Electron Flow-Induced H2O2 Formation Is Decreased in α-Ketoglutarate Dehydrogenase (α-KGDH) Subunit (E2 or E3) Heterozygote Knock Out Animals}, url = {https://m2.mtmt.hu/api/publication/33070137}, author = {Horváth, Gergő and Sváb, Gergely and Komlódi, Tímea and Ravasz, Dóra and Kacsó, Gergely and Dóczi, Judit and Chinopoulos, Christos and Ambrus, Attila and Tretter, László}, doi = {10.3390/antiox11081487}, journal-iso = {ANTIOXIDANTS-BASEL}, journal = {ANTIOXIDANTS}, volume = {11}, unique-id = {33070137}, abstract = {α-ketoglutarate dehydrogenase complex (KGDHc), or 2-oxoglutarate dehydrogenase complex (OGDHc) is a rate-limiting enzyme in the tricarboxylic acid cycle, that has been identified in neurodegenerative diseases such as in Alzheimer’s disease. The aim of the present study was to establish the role of the KGDHc and its subunits in the bioenergetics and reactive oxygen species (ROS) homeostasis of brain mitochondria. To study the bioenergetic profile of KGDHc, genetically modified mouse strains were used having a heterozygous knock out (KO) either in the dihydrolipoyl succinyltransferase (DLST+/−) or in the dihydrolipoyl dehydrogenase (DLD+/−) subunit. Mitochondrial oxygen consumption, hydrogen peroxide (H2O2) production, and expression of antioxidant enzymes were measured in isolated mouse brain mitochondria. Here, we demonstrate that the ADP-stimulated respiration of mitochondria was partially arrested in the transgenic animals when utilizing α-ketoglutarate (α-KG or 2-OG) as a fuel substrate. Succinate and α-glycerophosphate (α-GP), however, did not show this effect. The H2O2 production in mitochondria energized with α-KG was decreased after inhibiting the adenine nucleotide translocase and Complex I (CI) in the transgenic strains compared to the controls. Similarly, the reverse electron transfer (RET)-evoked H2O2 formation supported by succinate or α-GP were inhibited in mitochondria isolated from the transgenic animals. The decrease of RET-evoked ROS production by DLST+/− or DLD+/− KO-s puts the emphasis of the KGDHc in the pathomechanism of ischemia-reperfusion evoked oxidative stress. Supporting this notion, expression of the antioxidant enzyme glutathione peroxidase was also decreased in the KGDHc transgenic animals suggesting the attenuation of ROS-producing characteristics of KGDHc. These findings confirm the contribution of the KGDHc to the mitochondrial ROS production and in the pathomechanism of ischemia-reperfusion injury.}, year = {2022}, eissn = {2076-3921}, orcid-numbers = {Horváth, Gergő/0000-0001-5386-9509; Sváb, Gergely/0000-0002-7669-8252; Komlódi, Tímea/0000-0001-9876-1411; Ravasz, Dóra/0000-0002-0510-3282; Kacsó, Gergely/0000-0003-0428-3645; Dóczi, Judit/0000-0002-5797-5074; Chinopoulos, Christos/0000-0003-0183-4149; Ambrus, Attila/0000-0001-6014-3175; Tretter, László/0000-0001-5638-2886} } @article{MTMT:32813300, title = {Proline Oxidation Supports Mitochondrial ATP Production When Complex I Is Inhibited}, url = {https://m2.mtmt.hu/api/publication/32813300}, author = {Pallag, Gergely and Nazarian, Sara and Ravasz, Dóra and Bui, Dávid and Komlódi, Tímea and Carolina, Doerrier and Erich, Gnaiger and Thomas N., Seyfried and Chinopoulos, Christos}, doi = {10.3390/ijms23095111}, journal-iso = {INT J MOL SCI}, journal = {INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES}, volume = {23}, unique-id = {32813300}, issn = {1661-6596}, year = {2022}, eissn = {1422-0067}, orcid-numbers = {Pallag, Gergely/0000-0003-4093-162X; Ravasz, Dóra/0000-0002-0510-3282; Bui, Dávid/0000-0003-3726-2031; Komlódi, Tímea/0000-0001-9876-1411; Carolina, Doerrier/0000-0002-7969-6762; Erich, Gnaiger/0000-0003-3647-5895; Chinopoulos, Christos/0000-0003-0183-4149} } @article{MTMT:32218179, title = {Can the mitochondrial metabolic theory explain better the origin and management of cancer than can the somatic mutation theory?}, url = {https://m2.mtmt.hu/api/publication/32218179}, author = {Seyfried, T.N. and Chinopoulos, Christos}, doi = {10.3390/metabo11090572}, journal-iso = {METABOLITES}, journal = {METABOLITES}, volume = {11}, unique-id = {32218179}, issn = {2218-1989}, year = {2021}, eissn = {2218-1989}, orcid-numbers = {Chinopoulos, Christos/0000-0003-0183-4149} } @article{MTMT:32072787, title = {The mystery of extramitochondrial proteins lysine succinylation}, url = {https://m2.mtmt.hu/api/publication/32072787}, author = {Chinopoulos, Christos}, doi = {10.3390/ijms22116085}, journal-iso = {INT J MOL SCI}, journal = {INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES}, volume = {22}, unique-id = {32072787}, issn = {1661-6596}, abstract = {Lysine succinylation is a post-translational modification which alters protein function in both physiological and pathological processes. Mindful that it requires succinyl-CoA, a metabolite formed within the mitochondrial matrix that cannot permeate the inner mitochondrial membrane, the question arises as to how there can be succinylation of proteins outside mitochondria. The present mini-review examines pathways participating in peroxisomal fatty acid oxidation that lead to succinyl-CoA production, potentially supporting succinylation of extramitochondrial proteins. Furthermore, the influence of the mitochondrial status on cytosolic NAD+ availability affecting the activity of cytosolic SIRT5 iso1 and iso4—in turn regulating cytosolic protein lysine succinylations—is presented. Finally, the discovery that glia in the adult human brain lack subunits of both alpha-ketoglutarate dehydrogenase complex and succinate-CoA ligase—thus being unable to produce succinyl-CoA in the matrix—and yet exhibit robust pancellular lysine succinylation, is highlighted. © 2021 by the author. Licensee MDPI, Basel, Switzerland.}, keywords = {LYSINE; Post-translational modification; PEROXISOMES; fatty acid oxidation; Ketoglutarate Dehydrogenase Complex; Succinyl-CoA}, year = {2021}, eissn = {1422-0067}, orcid-numbers = {Chinopoulos, Christos/0000-0003-0183-4149} }