bims-mibica 2024-07-07 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024–07–07
25 papers selected by
Kelsey Fisher-Wellman, East Carolina University

SLC25A19 is required for NADH homeostasis and mitochondrial respiration.
Venetoclax resistance in acute lymphoblastic leukemia is characterized by increased mitochondrial activity and can be overcome by co-targeting oxidative phosphorylation.
Bridging lipid metabolism and mitochondrial genome maintenance.
E-cadherin Induces Serine Synthesis to Support Progression and Metastasis of Breast Cancer.
Perturbations in mitochondrial metabolism associated with defective cardiolipin biosynthesis: An in-organello real-time NMR study.
Combining the novel FLT3 and MERTK dual inhibitor MRX-2843 with venetoclax results in promising antileukemic activity against FLT3-ITD AML.
GTPBP8 plays a role in mitoribosome formation in human mitochondria.
N-Myristoyltransferase Inhibition causes Mitochondrial Iron Overload and Parthanatos in TIM17A-dependent Aggressive Lung Carcinoma.
From whence it came: Mitochondrial mRNA leaves, a protein returns.
Trafficking of mitochondrial double-stranded RNA from mitochondria to the cytosol.
TRIM2 promotes metabolic adaptation to glutamine deprivation via enhancement of CPT1A activity.
Coenzyme A protects against ferroptosis via CoAlation of thioredoxin reductase 2.
Overexpression of mitochondrial fission or mitochondrial fusion genes enhances resilience and extends longevity.
Interactions of Fatty Acid and Cholesterol Metabolism with Cellular Stress Response Pathways in Cancer.
MCT1-dependent lactate recycling is a metabolic vulnerability in colorectal cancer cells upon acquired resistance to anti-EGFR targeted therapy.
Fit for purpose: Selecting the best mitochondrial DNA for the job.
Structural Basis for Substrate Binding, Catalysis and Inhibition of Breast Cancer Target Mitochondrial Creatine Kinase by Covalent Inhibitor via Cryo-EM.
Mitochondrial genetics through the lens of single-cell multi-omics.
Asparagine Dependency is a Targetable Metabolic Vulnerability in TP53-Altered Castration-Resistant Prostate Cancer.
NAD metabolism-related genes provide prognostic value and potential therapeutic insights for acute myeloid leukemia.
Bioenergetic myths of energy transduction in eukaryotic cells.
Selective nitration of Hsp90 acts as a metabolic switch promoting tumor cell proliferation.
NBS1 lactylation is required for efficient DNA repair and chemotherapy resistance.
CRISPR-Cas9 screen identifies oxidative phosphorylation as essential for cancer cell survival at low extracellular pH.
Beyond fission and fusion-Diving into the mysteries of mitochondrial shape.

Free Radic Biol Med. 2024 Jun 27. pii: S0891-5849(24)00536-7. [Epub ahead of print]222 317-330

SLC25A19 is required for NADH homeostasis and mitochondrial respiration.

Zongsheng Jiang.

  Mitochondrial transporters facilitate the translocation of metabolites between the cytoplasm and mitochondria and are critical for mitochondrial functional integrity. Although many mitochondrial transporters are associated with metabolic diseases, how they regulate mitochondrial function and their metabolic contributions at the cellular level are largely unknown. Here, we show that mitochondrial thiamine pyrophosphate (TPP) transporter SLC25A19 is required for mitochondrial respiration. SLC25A19 deficiency leads to reduced cell viability, increased integrated stress response (ISR), enhanced glycolysis and elevated cell sensitivity to 2-deoxyglucose (2-DG) treatment. Through a series of biochemical assays, we found that the depletion of mitochondrial NADH is the primary cause of the impaired mitochondrial respiration in SLC25A19 deficient cells. We also showed involvement of SLC25A19 in regulating the enzymatic activities of complexes I and III, the tricarboxylic acid (TCA) cycle, malate-aspartate shuttle and amino acid metabolism. Consistently, addition of idebenone, an analog of coenzyme Q10, restores mitochondrial respiration and cell viability in SLC25A19 deficient cells. Together, our findings provide new insight into the functions of SLC25A19 in mitochondrial and cellular physiology, and suggest that restoring mitochondrial respiration could be a novel strategy for treating SLC25A19-associated disorders.

Keywords:  Electron transport chain; Idebenone; Mitochondrial respiration; Mitochondrial transporter; NADH; SLC25A19; TPP

DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.06.019
Cell Death Dis. 2024 Jul 03. 15(7): 475

Venetoclax resistance in acute lymphoblastic leukemia is characterized by increased mitochondrial activity and can be overcome by co-targeting oxidative phosphorylation.

Stefanie Enzenmüller, Alexandra Niedermayer, Felix Seyfried, Vera Muench, Daniel Tews, Ulrich Rupp, Eugen Tausch, Alexander Groß, Pamela Fischer-Posovszky, Paul Walther, Stephan Stilgenbauer, Hans A Kestler, Klaus-Michael Debatin, Lüder Hinrich Meyer.

Deregulated apoptosis signaling is characteristic for many cancers and contributes to leukemogenesis and treatment failure in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Apoptosis is controlled by different pro- and anti-apoptotic molecules. Inhibition of anti-apoptotic molecules like B-cell lymphoma 2 (BCL-2) has been developed as therapeutic strategy. Venetoclax (VEN), a selective BCL-2 inhibitor has shown clinical activity in different lymphoid malignancies and is currently evaluated in first clinical trials in BCP-ALL. However, insensitivity to VEN has been described constituting a major clinical concern. Here, we addressed and modeled VEN-resistance in BCP-ALL, investigated the underlying mechanisms in cell lines and patient-derived xenograft (PDX) samples and identified potential strategies to overcome VEN-insensitivity. Leukemia lines with VEN-specific resistance were generated in vitro and further characterized using RNA-seq analysis. Interestingly, gene sets annotated to the citric/tricarboxylic acid cycle and the respiratory electron transport chain were significantly enriched and upregulated, indicating increased mitochondrial metabolism in VEN-resistant ALL. Metabolic profiling showed sustained high mitochondrial metabolism in VEN-resistant lines as compared to control lines. Accordingly, primary PDX-ALL samples with intrinsic VEN-insensitivity showed higher oxygen consumption and ATP production rates, further highlighting that increased mitochondrial activity is a characteristic feature of VEN-resistant ALL. VEN-resistant PDX-ALL showed significant higher mitochondrial DNA content and differed in mitochondria morphology with significantly larger and elongated structures, further corroborating our finding of augmented mitochondrial metabolism upon VEN-resistance. Using Oligomycin, an inhibitor of the complex V/ATPase subunit, we found synergistic activity and apoptosis induction in VEN-resistant BCP-ALL cell lines and PDX samples, demonstrating that acquired and intrinsic VEN-insensitivity can be overcome by co-targeting BCL-2 and the OxPhos pathway. These findings of reprogrammed, high mitochondrial metabolism in VEN-resistance and synergistic activity upon co-targeting BCL-2 and oxidative phosphorylation strongly suggest further preclinical and potential clinical evaluation in VEN-resistant BCP-ALL.

DOI: https://doi.org/10.1038/s41419-024-06864-7
J Biol Chem. 2024 Jun 27. pii: S0021-9258(24)01999-9. [Epub ahead of print] 107498

Bridging lipid metabolism and mitochondrial genome maintenance.

Casadora Boone, Samantha C Lewis.

  Mitochondria are the nexus of cellular energy metabolism and major signaling hubs that integrate information from within and without the cell to implement cell function. Mitochondria harbor a distinct polyploid genome, mitochondrial DNA (mtDNA), that encodes respiratory chain components required for energy production. MtDNA mutation and depletion have been linked to obesity and metabolic syndrome in humans. At the cellular and subcellular levels, mtDNA synthesis is coordinated by membrane contact sites implicated in lipid transfer from the endoplasmic reticulum, tying genome maintenance to lipid storage and homeostasis. Here, we examine the relationship between mtDNA and lipid trafficking, the influence of lipotoxicity on mtDNA integrity, and how lipid metabolism may be disrupted in primary mtDNA disease.

Keywords:  Mitochondria; lipid metabolism; lipotoxicity; mitochondrial DNA (mtDNA); mitochondrial metabolism

DOI:  https://doi.org/10.1016/j.jbc.2024.107498
Cancer Res. 2024 Jul 03.

E-cadherin Induces Serine Synthesis to Support Progression and Metastasis of Breast Cancer.

Geonhui Lee, Claudia Wong, Anna Cho, Junior J West, Ashleigh J Crawford, Gabriella C Russo, Bishwa Ranjan Si, Jungwoo Kim, Lauren Hoffner, Cholsoon Jang, Moonjung Jung, Robert D Leone, Konstantinos Konstantopoulos, Andrew J Ewald, Denis Wirtz, Sangmoo Jeong.

The loss of E-cadherin, an epithelial cell adhesion molecule, has been implicated in metastasis by mediating the epithelial-mesenchymal transition (EMT), which promotes invasion and migration of cancer cells. However, recent studies have demonstrated that E-cadherin supports the survival and proliferation of metastatic cancer cells. Here, we identified a metabolic role for E-cadherin in breast cancer by upregulating the de novo serine synthesis pathway (SSP). The upregulated SSP provided metabolic precursors for biosynthesis and resistance to oxidative stress, enabling E-cadherin+ breast cancer cells to achieve faster tumor growth and enhanced metastases. Inhibition of PHGDH, a rate-limiting enzyme in the SSP, significantly and specifically hampered proliferation of E-cadherin+ breast cancer cells and rendered them vulnerable to oxidative stress, inhibiting their metastatic potential. These findings reveal that E-cadherin reprograms cellular metabolism, promoting tumor growth and metastasis of breast cancers.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-3082
bioRxiv. 2024 Jun 22. pii: 2024.06.18.599628. [Epub ahead of print]

Perturbations in mitochondrial metabolism associated with defective cardiolipin biosynthesis: An in-organello real-time NMR study.

Antonio J Rua, Wayne Mitchell, Steven M Claypool, Nathan N Alder, Andrei T Alexandrescu.

Mitochondria are central to cellular metabolism; hence, their dysfunction contributes to a wide array of human diseases including cancer, cardiopathy, neurodegeneration, and heritable pathologies such as Barth syndrome. Cardiolipin, the signature phospholipid of the mitochondrion promotes proper cristae morphology, bioenergetic functions, and directly affects metabolic reactions carried out in mitochondrial membranes. To match tissue-specific metabolic demands, cardiolipin typically undergoes an acyl tail remodeling process with the final step carried out by the phospholipid-lysophospholipid transacylase tafazzin. Mutations in the tafazzin gene are the primary cause of Barth syndrome. Here, we investigated how defects in cardiolipin biosynthesis and remodeling impact metabolic flux through the tricarboxylic acid cycle and associated pathways in yeast. Nuclear magnetic resonance was used to monitor in real-time the metabolic fate of 13 C 3 -pyruvate in isolated mitochondria from three isogenic yeast strains. We compared mitochondria from a wild-type strain to mitochondria from a Δ taz1 strain that lacks tafazzin and contains lower amounts of unremodeled cardiolipin, and mitochondria from a Δ crd1 strain that lacks cardiolipin synthase and cannot synthesize cardiolipin. We found that the 13 C-label from the pyruvate substrate was distributed through about twelve metabolites. Several of the identified metabolites were specific to yeast pathways, including branched chain amino acids and fusel alcohol synthesis. Most metabolites showed similar kinetics amongst the different strains but mevalonate and α-ketoglutarate, as well as the NAD+/NADH couple measured in separate nuclear magnetic resonance experiments, showed pronounced differences. Taken together, the results show that cardiolipin remodeling influences pyruvate metabolism, tricarboxylic acid cycle flux, and the levels of mitochondrial nucleotides.

DOI: https://doi.org/10.1101/2024.06.18.599628
Leuk Res. 2024 Jun 24. pii: S0145-2126(24)00113-9. [Epub ahead of print]144 107547

Combining the novel FLT3 and MERTK dual inhibitor MRX-2843 with venetoclax results in promising antileukemic activity against FLT3-ITD AML.

Shuangshuang Wu, Fangbing Liu, Yuqing Gai, Jenna Carter, Holly Edwards, Maik Hüttemann, Guan Wang, Chunhuai Li, Jeffrey W Taub, Yue Wang, Yubin Ge.

  FMS-like tyrosine kinase 3 (FLT3) mutations occur in approximately one third of acute myeloid leukemia (AML) patients. FLT3-Internal tandem duplication (FLT3-ITD) mutations are the most common FLT3 mutations and are associated with a poor prognosis. Gilteritinib is a FLT3 inhibitor that is US FDA approved for treating adult patients with relapsed/refractory AML and a FLT3 mutation. While gilteritinib monotherapy has improved patient outcome, few patients achieve durable responses. Combining gilteritinib with venetoclax (VEN) appears to make further improvements, though early results suggest that patients with prior exposure to VEN fair much worse than those without prior exposure. MRX-2843 is a promising inhibitor of FLT3 and MERTK. We recently demonstrated that MRX-2843 is equally potent as gilteritinib in FLT3-ITD AML cell lines in vitro and primary patient samples ex vivo. In this study, we investigated the combination of VEN and MRX-2843 against FLT3-ITD AML cells. We found that VEN synergistically enhances cell death induced by MRX-2843 in FLT3-mutated AML cell lines and primary patient samples. Importantly, we found that VEN synergistically enhances cell death induced by MRX-2843 in FLT3-ITD AML cells with acquired resistance to cytarabine (AraC) or VEN+AraC. VEN and MRX-2843 significantly reduce colony-forming capacity of FLT3-ITD primary AML cells. Mechanistic studies show that MRX-2843 decreases Mcl-1 and c-Myc protein levels via transcriptional regulation and combined MRX-2843 and VEN significantly decreases oxidative phosphorylation in FLT3-ITD AML cells. Our findings highlight a promising combination therapy against FLT3-ITD AML, supporting further in vitro and in vivo testing.

Keywords:  Acute myeloid leukemia; Bcl-2; FLT3-ITD; MRX-2843; Venetoclax

DOI:  https://doi.org/10.1016/j.leukres.2024.107547
Nat Commun. 2024 Jul 05. 15(1): 5664

GTPBP8 plays a role in mitoribosome formation in human mitochondria.

Miriam Cipullo, Genís Valentín Gesé, Shreekara Gopalakrishna, Annika Krueger, Vivian Lobo, Maria A Pirozhkova, James Marks, Petra Páleníková, Dmitrii Shiriaev, Yong Liu, Jelena Misic, Yu Cai, Minh Duc Nguyen, Abubakar Abdelbagi, Xinping Li, Michal Minczuk, Markus Hafner, Daniel Benhalevy, Aishe A Sarshad, Ilian Atanassov, B Martin Hällberg, Joanna Rorbach.

Mitochondrial gene expression relies on mitoribosomes to translate mitochondrial mRNAs. The biogenesis of mitoribosomes is an intricate process involving multiple assembly factors. Among these factors, GTP-binding proteins (GTPBPs) play important roles. In bacterial systems, numerous GTPBPs are required for ribosome subunit maturation, with EngB being a GTPBP involved in the ribosomal large subunit assembly. In this study, we focus on exploring the function of GTPBP8, the human homolog of EngB. We find that ablation of GTPBP8 leads to the inhibition of mitochondrial translation, resulting in significant impairment of oxidative phosphorylation. Structural analysis of mitoribosomes from GTPBP8 knock-out cells shows the accumulation of mitoribosomal large subunit assembly intermediates that are incapable of forming functional monosomes. Furthermore, fPAR-CLIP analysis reveals that GTPBP8 is an RNA-binding protein that interacts specifically with the mitochondrial ribosome large subunit 16 S rRNA. Our study highlights the role of GTPBP8 as a component of the mitochondrial gene expression machinery involved in mitochondrial large subunit maturation.

DOI: https://doi.org/10.1038/s41467-024-50011-x
Cancer Res Commun. 2024 Jul 01.

N-Myristoyltransferase Inhibition causes Mitochondrial Iron Overload and Parthanatos in TIM17A-dependent Aggressive Lung Carcinoma.

Sofia Geroyska, Isabel Mejia, Alfred A Chan, Marian Navarrete, Vijaya Pandey, Samuel Kharpatin, Juliana Noguti, Feng Wang, Daniel Srole, Tsui-Fen Chou, James Wohlschlegel, Elizabeta Nemeth, Robert Damoiseaux, David B Shackelford, Delphine J Lee, Begoña Diaz.

Myristoylation is a type of protein acylation by which the fatty acid myristate is added to the N-terminus of target proteins, a process mediated by N-myristoyltransferases. Myristoylation is emerging as a promising cancer therapeutic target, however the molecular determinants of sensitivity to N-myristoyltransferase inhibition or the mechanism by which it induces cancer cell death are not completely understood. We report that N-myristoyltransferases are a novel therapeutic target in lung carcinoma cells with LKB1 and/or KEAP1 mutations in a KRAS mutant background. Inhibition of myristoylation decreases cell viability in vitro and tumor growth in vivo. Inhibition of myristoylation causes mitochondrial ferrous iron overload, oxidative stress, elevated protein poly (ADP)-ribosylation and death by parthanatos. Furthermore, NMT inhibitors sensitized lung carcinoma cells to platinum-based chemotherapy. Unexpectedly, the mitochondrial transporter Translocase of Inner Mitochondrial Membrane 17 homologue A (TIM17A) is a critical target of myristoylation inhibitors in these cells. TIM17A silencing recapitulated the effects of NMT inhibition at inducing mitochondrial ferrous iron overload and parthanatos. Furthermore, sensitivity of lung carcinoma cells to myristoylation inhibition correlated with their dependency on TIM17A. This study reveals the unexpected connection between protein myristoylation, the mitochondrial import machinery, and iron homeostasis. It also uncovers myristoylation inhibitors as novel inducers of parthanatos in cancer, and the novel axis N-myristoyltransferase-TIM17A as a potential therapeutic target in highly aggressive lung carcinomas.

DOI: https://doi.org/10.1158/2767-9764.CRC-23-0428
Cell Metab. 2024 Jul 02. pii: S1550-4131(24)00227-4. [Epub ahead of print]36(7): 1433-1435

From whence it came: Mitochondrial mRNA leaves, a protein returns.

Kevin A Janssen, Angela Song.

Small peptides have previously been reported to be encoded in mitochondrial rRNA and translated by cytosolic ribosomes. In this issue of Cell Metabolism, Hu et al. use mass spectrometry to identify a cytosolically translated protein, encoded instead in mitochondrial mRNA, that is surprisingly targeted back into the mitochondrial matrix.

DOI: https://doi.org/10.1016/j.cmet.2024.06.002
Life Sci Alliance. 2024 Sep;pii: e202302396. [Epub ahead of print]7(9):

Trafficking of mitochondrial double-stranded RNA from mitochondria to the cytosol.

Matthew R Krieger, Melania Abrahamian, Kevin L He, Sean Atamdede, Hesamedin Hakimjavadi, Milica Momcilovic, Dejerianne Ostrow, Simran Ds Maggo, Yik Pui Tsang, Xiaowu Gai, Guillaume F Chanfreau, David B Shackelford, Michael A Teitell, Carla M Koehler.

In addition to mitochondrial DNA, mitochondrial double-stranded RNA (mtdsRNA) is exported from mitochondria. However, specific channels for RNA transport have not been demonstrated. Here, we begin to characterize channel candidates for mtdsRNA export from the mitochondrial matrix to the cytosol. Down-regulation of SUV3 resulted in the accumulation of mtdsRNAs in the matrix, whereas down-regulation of PNPase resulted in the export of mtdsRNAs to the cytosol. Targeting experiments show that PNPase functions in both the intermembrane space and matrix. Strand-specific sequencing of the double-stranded RNA confirms the mitochondrial origin. Inhibiting or down-regulating outer membrane proteins VDAC1/2 and BAK/BAX or inner membrane proteins PHB1/2 strongly attenuated the export of mtdsRNAs to the cytosol. The cytosolic mtdsRNAs subsequently localized to large granules containing the stress protein TIA-1 and activated the type 1 interferon stress response pathway. Abundant mtdsRNAs were detected in a subset of non-small-cell lung cancer cell lines that were glycolytic, indicating relevance in cancer biology. Thus, we propose that mtdsRNA is a new damage-associated molecular pattern that is exported from mitochondria in a regulated manner.

DOI: https://doi.org/10.26508/lsa.202302396
FEBS J. 2024 Jul 01.

TRIM2 promotes metabolic adaptation to glutamine deprivation via enhancement of CPT1A activity.

Kaimin Liao, Kaiyue Liu, Zhongyu Wang, Kailiang Zhao, Yide Mei.

  Cancer cells undergo metabolic adaptation to promote their survival and growth under energy stress conditions, yet the underlying mechanisms remain largely unclear. Here, we report that tripartite motif-containing protein 2 (TRIM2) is upregulated in response to glutamine deprivation by the transcription factor cyclic AMP-dependent transcription factor (ATF4). TRIM2 is shown to specifically interact with carnitine O-palmitoyltransferase 1 (CPT1A), a rate-limiting enzyme of fatty acid oxidation. Via this interaction, TRIM2 enhances the enzymatic activity of CPT1A, thereby regulating intracellular lipid levels and protecting cells from glutamine deprivation-induced apoptosis. Furthermore, TRIM2 is able to promote both in vitro cell proliferation and in vivo xenograft tumor growth via CPT1A. Together, these findings establish TRIM2 as an important regulator of the metabolic adaptation of cancer cells to glutamine deprivation and implicate TRIM2 as a potential therapeutic target for cancer.

Keywords:  CPT1A; TRIM2; glutamine deprivation; metabolic adaptation

DOI:  https://doi.org/10.1111/febs.17218
Res Sq. 2024 Jun 18. pii: rs.3.rs-4522617. [Epub ahead of print]

Coenzyme A protects against ferroptosis via CoAlation of thioredoxin reductase 2.

Jen-Tsan Chi, Chao Chieh Lin, Yi-Tzu Lin, Ssu-Yu Chen, Yasaman Setayeshpour, Yubin Chen, Denise Dunn, Erik Soderblom, Guo-Fang Zhang, Valeriy Filonenko, Suh Young Jeong, Scott Floyd, Susan Hayflick, Ivan Gout.

The Cystine-xCT transporter-Glutathione (GSH)-GPX4 axis is the canonical pathway to protect against ferroptosis. While not required for ferroptosis-inducing compounds (FINs) targeting GPX4, FINs targeting the xCT transporter require mitochondria and its lipid peroxidation to trigger ferroptosis. However, the mechanism underlying the difference between these FINs is still unknown. Given that cysteine is also required for coenzyme A (CoA) biosynthesis, here we show that CoA supplementation specifically prevents ferroptosis induced by xCT inhibitors but not GPX4 inhibitors. We find that, auranofin, a thioredoxin reductase inhibitor, abolishes the protective effect of CoA. We also find that CoA availability determines the enzymatic activity of thioredoxin reductase, but not thioredoxin. Importantly, the mitochondrial thioredoxin system, but not the cytosolic thioredoxin system, determines CoA-mediated ferroptosis inhibition. Our data show that the CoA regulates the in vitro enzymatic activity of mitochondrial thioredoxin reductase (TXNRD2) by covalently modifying the thiol group of cysteine (CoAlation) on Cys-483. Replacing Cys-483 with alanine on TXNRD2 abolishes its in vitro enzymatic activity and ability to protect cells from ferroptosis. Targeting xCT to limit cysteine import and, therefore, CoA biosynthesis reduced CoAlation on TXNRD2, an effect that was rescued by CoA supplementation. Furthermore, the fibroblasts from patients with disrupted CoA metabolism demonstrate increased mitochondrial lipid peroxidation. In organotypic brain slice cultures, inhibition of CoA biosynthesis leads to an oxidized thioredoxin system, mitochondrial lipid peroxidation, and loss in cell viability, which were all rescued by ferrostatin-1. These findings identify CoA-mediated post-translation modification to regulate the thioredoxin system as an alternative ferroptosis protection pathway with potential clinical relevance for patients with disrupted CoA metabolism.

DOI: https://doi.org/10.21203/rs.3.rs-4522617/v1
Aging Cell. 2024 Jul 02. e14262

Overexpression of mitochondrial fission or mitochondrial fusion genes enhances resilience and extends longevity.

Annika Traa, Allison Keil, Abdelrahman AlOkda, Suleima Jacob-Tomas, Aura A Tamez González, Shusen Zhu, Zenith Rudich, Jeremy M Van Raamsdonk.

  The dynamicity of the mitochondrial network is crucial for meeting the ever-changing metabolic and energy needs of the cell. Mitochondrial fission promotes the degradation and distribution of mitochondria, while mitochondrial fusion maintains mitochondrial function through the complementation of mitochondrial components. Previously, we have reported that mitochondrial networks are tubular, interconnected, and well-organized in young, healthy C. elegans, but become fragmented and disorganized with advancing age and in models of age-associated neurodegenerative disease. In this work, we examine the effects of increasing mitochondrial fission or mitochondrial fusion capacity by ubiquitously overexpressing the mitochondrial fission gene drp-1 or the mitochondrial fusion genes fzo-1 and eat-3, individually or in combination. We then measured mitochondrial function, mitochondrial network morphology, physiologic rates, stress resistance, and lifespan. Surprisingly, we found that overexpression of either mitochondrial fission or fusion machinery both resulted in an increase in mitochondrial fragmentation. Similarly, both mitochondrial fission and mitochondrial fusion overexpression strains have extended lifespans and increased stress resistance, which in the case of the mitochondrial fusion overexpression strains appears to be at least partially due to the upregulation of multiple pathways of cellular resilience in these strains. Overall, our work demonstrates that increasing the expression of mitochondrial fission or fusion genes extends lifespan and improves biological resilience without promoting the maintenance of a youthful mitochondrial network morphology. This work highlights the importance of the mitochondria for both resilience and longevity.

Keywords:   C. elegans ; aging; biological resilience; genetics; lifespan; mitochondria; mitochondrial fission; mitochondrial fusion

DOI:  https://doi.org/10.1111/acel.14262
Cold Spring Harb Perspect Med. 2024 Jul 01. pii: a041548. [Epub ahead of print]

Interactions of Fatty Acid and Cholesterol Metabolism with Cellular Stress Response Pathways in Cancer.

Alina M Winkelkotte, Kamal Al-Shami, Adriano B Chaves-Filho, Felix C E Vogel, Almut Schulze.

Lipids have essential functions as structural components of cellular membranes, as efficient energy storage molecules, and as precursors of signaling mediators. While deregulated glucose and amino acid metabolism in cancer have received substantial attention, the roles of lipids in the metabolic reprogramming of cancer cells are less well understood. However, since the first description of de novo fatty acid biosynthesis in cancer tissues almost 70 years ago, numerous studies have investigated the complex functions of altered lipid metabolism in cancer. Here, we will summarize the mechanisms by which oncogenic signaling pathways regulate fatty acid and cholesterol metabolism to drive rapid proliferation and protect cancer cells from environmental stress. The review also discusses the role of fatty acid metabolism in metabolic plasticity required for the adaptation to changing microenvironments during cancer progression and the connections between fatty acid and cholesterol metabolism and ferroptosis.

DOI: https://doi.org/10.1101/cshperspect.a041548
Cancer Lett. 2024 Jul 02. pii: S0304-3835(24)00486-5. [Epub ahead of print] 217091

MCT1-dependent lactate recycling is a metabolic vulnerability in colorectal cancer cells upon acquired resistance to anti-EGFR targeted therapy.

Elena Richiardone, Rim Al Roumi, Fanny Lardinois, Maria Virginia Giolito, Jérôme Ambroise, Romain Boidot, Bernhard Drotleff, Bart Ghesquière, Akeila Bellahcène, Alberto Bardelli, Sabrina Arena, Cyril Corbet.

  Despite the implementation of personalized medicine, patients with metastatic CRC (mCRC) still have a dismal overall survival due to the frequent occurrence of acquired resistance mechanisms thereby leading to clinical relapse. Understanding molecular mechanisms that support acquired resistance to anti-EGFR targeted therapy in mCRC is therefore clinically relevant and key to improving patient outcomes. Here, we observe distinct metabolic changes between cetuximab-resistant CRC cell populations, with in particular an increased glycolytic activity in KRAS-mutant cetuximab-resistant CRC cells (LIM1215 and OXCO2) but not in KRAS-amplified resistant DiFi cells. We show that cetuximab-resistant LIM1215 and OXCO2 cells have the capacity to recycle glycolysis-derived lactate to sustain their growth capacity. This is associated with an upregulation of the lactate importer MCT1 at both transcript and protein levels. Pharmacological inhibition of MCT1, with AR-C155858, reduces the uptake and oxidation of lactate and impairs growth capacity in cetuximab-resistant LIM1215 cells both in vitro and in vivo. This study identifies MCT1-dependent lactate utilization as a clinically actionable, metabolic vulnerability to overcome KRAS-mutant-mediated acquired resistance to anti-EGFR therapy in CRC.

Keywords:  Colorectal cancer; KRAS; cetuximab; lactate; metabolism; monocarboxylate transporter; therapy resistance

DOI:  https://doi.org/10.1016/j.canlet.2024.217091
Cell Metab. 2024 Jul 02. pii: S1550-4131(24)00236-5. [Epub ahead of print]36(7): 1436-1438

Fit for purpose: Selecting the best mitochondrial DNA for the job.

Sarah J Pickett, Robert W Taylor, Robert McFarland.

The factors determining levels of pathogenic mitochondrial DNA in cells and tissues are critical to disease pathology but remain poorly understood and contentious. In Nature, Kotrys et al. published a single-cell-based analysis casting fresh light on this thorny problem and introduced a powerful new investigative tool.

DOI: https://doi.org/10.1016/j.cmet.2024.06.011
bioRxiv. 2024 Jun 18. pii: 2024.06.18.598884. [Epub ahead of print]

Structural Basis for Substrate Binding, Catalysis and Inhibition of Breast Cancer Target Mitochondrial Creatine Kinase by Covalent Inhibitor via Cryo-EM.

Merve Demir, Laura Koepping, Ya Li, Lynn Fujimoto, Andrey Bobkov, Jianhua Zhao, Taro Hitosugi, Eduard Sergienko.

Mitochondrial creatine kinases are key players in maintaining energy homeostasis in cells by working in conjunction with cytosolic creatine kinases for energy transport from mitochondria to cytoplasm. High levels of MtCK observed in Her2+ breast cancer and inhibition of breast cancer cell growth by substrate analog, cyclocreatine, indicate dependence of cancer cells on the 'energy shuttle' for cell growth and survival. Hence, understanding the key mechanistic features of creatine kinases and their inhibition plays an important role in the development of cancer therapeutics. Herein, we present the mutational and structural investigation on understudied ubiquitous mitochondrial creatine kinase (uMtCK). Our cryo-EM structures and biochemical data on uMtCK showed closure of the loop comprising residue His61 is specific to and relies on creatine binding and the reaction mechanism of phosphoryl transfer depends on electrostatics in the active site. In addition, the previously identified covalent inhibitor CKi showed inhibition in breast cancer BT474 cells, however our biochemical and structural data indicated that CKi is not a potent inhibitor for breast cancer due to strong dependency on the covalent link formation and inability to induce conformational changes upon binding.

DOI: https://doi.org/10.1101/2024.06.18.598884
Nat Genet. 2024 Jul 01.

Mitochondrial genetics through the lens of single-cell multi-omics.

Lena Nitsch, Caleb A Lareau, Leif S Ludwig.

Mitochondria carry their own genetic information encoding for a subset of protein-coding genes and translational machinery essential for cellular respiration and metabolism. Despite its small size, the mitochondrial genome, its natural genetic variation and molecular phenotypes have been challenging to study using bulk sequencing approaches, due to its variation in cellular copy number, non-Mendelian modes of inheritance and propensity for mutations. Here we highlight emerging strategies designed to capture mitochondrial genetic variation across individual cells for lineage tracing and studying mitochondrial genetics in primary human cells and clinical specimens. We review recent advances surrounding single-cell mitochondrial genome sequencing and its integration with functional genomic readouts, including leveraging somatic mitochondrial DNA mutations as clonal markers that can resolve cellular population dynamics in complex human tissues. Finally, we discuss how single-cell whole mitochondrial genome sequencing approaches can be utilized to investigate mitochondrial genetics and its contribution to cellular heterogeneity and disease.

DOI: https://doi.org/10.1038/s41588-024-01794-8
Cancer Res. 2024 Jul 03.

Asparagine Dependency is a Targetable Metabolic Vulnerability in TP53-Altered Castration-Resistant Prostate Cancer.

Young A Yoo, Songhua Quan, William Yang, Qianyu Guo, Yara Rodríguez, Zachary R Chalmers, Mary F Dufficy, Barbara Lackie, Vinay Sagar, Kenji Unno, Mihai I Truica, Navdeep S Chandel, Sarki A Abdulkadir.

The TP53 tumor suppressor is frequently altered in lethal, castration-resistant prostate cancer (CRPC). However, to date there are no effective treatments that specifically target TP53 alterations. Using transcriptomic and metabolomic analyses, we showed here that TP53-altered prostate cancer (PCa) exhibits an increased dependency on asparagine and overexpresses asparagine synthetase (ASNS), the enzyme catalyzing the synthesis of asparagine. Mechanistically, loss or mutation of TP53 transcriptionally activated ASNS expression, directly as well as via mTORC1-mediated ATF4 induction, driving de novo asparagine biosynthesis to support CRPC growth. TP53-altered CRPC cells were sensitive to asparagine restriction by knockdown of ASNS or L-asparaginase treatment to deplete the intracellular and extracellular sources of asparagine, respectively, and cell viability was rescued by asparagine addition. Notably, pharmacological inhibition of intracellular asparagine biosynthesis using a glutaminase inhibitor and depletion of extracellular asparagine with L-asparaginase significantly reduced asparagine production and effectively impaired CRPC growth. This study highlights the significance of ASNS-mediated metabolic adaptation as a synthetic vulnerability in CRPC with TP53 alterations, providing a rationale for targeting asparagine production to treat these lethal prostate cancers.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-2910
Front Immunol. 2024 ;15 1417398

NAD metabolism-related genes provide prognostic value and potential therapeutic insights for acute myeloid leukemia.

Yuncan Cao, Wenjing Shu, Peng Jin, Jianfeng Li, Hongming Zhu, Xinjie Chen, Yongmei Zhu, Xi Huang, Wenyan Cheng, Yang Shen.

   Introduction: Acute myeloid leukemia (AML) is an aggressive blood cancer with high heterogeneity and poor prognosis. Although the metabolic reprogramming of nicotinamide adenine dinucleotide (NAD) has been reported to play a pivotal role in the pathogenesis of acute myeloid leukemia (AML), the prognostic value of NAD metabolism and its correlation with the immune microenvironment in AML remains unclear.
Methods: We utilized our large-scale RNA-seq data on 655 patients with AML and the NAD metabolism-related genes to establish a prognostic NAD metabolism score based on the sparse regression analysis. The signature was validated across three independent datasets including a total of 1,215 AML patients. ssGSEA and ESTIMATE algorithms were employed to dissect the tumor immune microenvironment. Ex vivo drug screening and in vitro experimental validation were performed to identify potential therapeutic approaches for the high-risk patients. In vitro knockdown and functional experiments were employed to investigate the role of SLC25A51, a mitochondrial NAD+ transporter gene implicated in the signature.
Results: An 8-gene NAD metabolism signature (NADM8) was generated and demonstrated a robust prognostic value in more than 1,800 patients with AML. High NADM8 score could efficiently discriminate AML patients with adverse clinical characteristics and genetic lesions and serve as an independent factor predicting a poor prognosis. Immune microenvironment analysis revealed significant enrichment of distinct tumor-infiltrating immune cells and activation of immune checkpoints in patients with high NADM8 scores, acting as a potential biomarker for immune response evaluation in AML. Furthermore, ex vivo drug screening and in vitro experimental validation in a panel of 9 AML cell lines demonstrated that the patients with high NADM8 scores were more sensitive to the PI3K inhibitor, GDC-0914. Finally, functional experiments also substantiated the critical pathogenic role of the SLC25A51 in AML, which could be a promising therapeutic target.
Conclusion: Our study demonstrated that NAD metabolism-related signature can facilitate risk stratification and prognosis prediction in AML and guide therapeutic decisions including both immunotherapy and targeted therapies.

Keywords:  NAD metabolism; acute myeloid leukemia; immune microenvironment; prognostic signature; targeted therapy

DOI:  https://doi.org/10.3389/fimmu.2024.1417398
Front Mol Biosci. 2024 ;11 1402910

Bioenergetic myths of energy transduction in eukaryotic cells.

Guy C Brown.

  The study of energy transduction in eukaryotic cells has been divided between Bioenergetics and Physiology, reflecting and contributing to a variety of Bioenergetic myths considered here: 1) ATP production = energy production, 2) energy transduction is confined to mitochondria (plus glycolysis and chloroplasts), 3) mitochondria only produce heat when required, 4) glycolysis is inefficient compared to mitochondria, and 5) mitochondria are the main source of reactive oxygen species (ROS) in cells. These myths constitute a 'mitocentric' view of the cell that is wrong or unbalanced. In reality, mitochondria are the main site of energy dissipation and heat production in cells, and this is an essential function of mitochondria in mammals. Energy transduction and ROS production occur throughout the cell, particularly the cytosol and plasma membrane, and all cell membranes act as two-dimensional energy conduits. Glycolysis is efficient, and produces less heat per ATP than mitochondria, which might explain its increased use in muscle and cancer cells.

Keywords:  Warburg effect; bioenergetics; cancer; cell metabolism; energetics; glycolysis; mitochondria; oxidative stress

DOI:  https://doi.org/10.3389/fmolb.2024.1402910
Redox Biol. 2024 Jun 19. pii: S2213-2317(24)00227-1. [Epub ahead of print]75 103249

Selective nitration of Hsp90 acts as a metabolic switch promoting tumor cell proliferation.

Isabelle E Logan, Kyle T Nguyen, Tilottama Chatterjee, Bhagyashree Manivannan, Ngozi P Paul, Sharon R Kim, Evelyn M Sixta, Lydia P Bastian, Carrie Marean-Reardon, Matthias A Karajannis, Cristina Fernández-Valle, Alvaro G Estevez, Maria Clara Franco.

  Tumors develop in an oxidative environment characterized by peroxynitrite production and downstream protein tyrosine (Y) nitration. We showed that tyrosine nitration supports schwannoma cell proliferation and regulates cell metabolism in the inheritable tumor disorder NF2-related Schwannomatosis (NF2-SWN). Here, we identified the chaperone Heat shock protein 90 (Hsp90) as the first nitrated protein that acts as a metabolic switch to promote schwannoma cell proliferation. Doubling the endogenous levels of nitrated Hsp90 in schwannoma cells or supplementing nitrated Hsp90 into normal Schwann cells increased their proliferation. Metabolically, nitration on either Y33 or Y56 conferred Hsp90 distinct functions; nitration at Y33 (Hsp90NY33) down-regulated mitochondrial oxidative phosphorylation, while nitration at Y56 (Hsp90NY56) increased glycolysis by activating the purinergic receptor P2X7 in both schwannoma and normal Schwann cells. Hsp90NY33 and Hsp90NY56 showed differential subcellular and spatial distribution corresponding with their metabolic and proliferative functions in schwannoma three-dimensional cell culture models. Collectively, these results underscore the role of tyrosine nitration as a post-translational modification regulating critical cellular processes. Nitrated proteins, particularly nitrated Hsp90, emerge as a novel category of tumor-directed therapeutic targets.

Keywords:  Cell metabolism; Hsp90; Neurofibromatosis; P2X7 receptor; Tumor; Tyrosine nitration

DOI:  https://doi.org/10.1016/j.redox.2024.103249
Nature. 2024 Jul 03.

NBS1 lactylation is required for efficient DNA repair and chemotherapy resistance.

Hengxing Chen, Yun Li, Huafu Li, Xiancong Chen, Huafeng Fu, Deli Mao, Wei Chen, Linxiang Lan, Chunming Wang, Kaishun Hu, Jia Li, Chengming Zhu, Ian Evans, Eddie Cheung, Daning Lu, Yulong He, Axel Behrens, Dong Yin, Changhua Zhang.

The Warburg effect is a hallmark of cancer that refers to the preference of cancer cells to metabolize glucose anaerobically rather than aerobically1,2. This results in substantial accumulation of lacate, the end product of anaerobic glycolysis, in cancer cells3. However, how cancer metabolism affects chemotherapy response and DNA repair in general remains incompletely understood. Here we report that lactate-driven lactylation of NBS1 promotes homologous recombination (HR)-mediated DNA repair. Lactylation of NBS1 at lysine 388 (K388) is essential for MRE11-RAD50-NBS1 (MRN) complex formation and the accumulation of HR repair proteins at the sites of DNA double-strand breaks. Furthermore, we identify TIP60 as the NBS1 lysine lactyltransferase and the 'writer' of NBS1 K388 lactylation, and HDAC3 as the NBS1 de-lactylase. High levels of NBS1 K388 lactylation predict poor patient outcome of neoadjuvant chemotherapy, and lactate reduction using either genetic depletion of lactate dehydrogenase A (LDHA) or stiripentol, a lactate dehydrogenase A inhibitor used clinically for anti-epileptic treatment, inhibited NBS1 K388 lactylation, decreased DNA repair efficacy and overcame resistance to chemotherapy. In summary, our work identifies NBS1 lactylation as a critical mechanism for genome stability that contributes to chemotherapy resistance and identifies inhibition of lactate production as a promising therapeutic cancer strategy.

DOI: https://doi.org/10.1038/s41586-024-07620-9
Cell Rep. 2024 Jul 02. pii: S2211-1247(24)00828-3. [Epub ahead of print]43(7): 114499

CRISPR-Cas9 screen identifies oxidative phosphorylation as essential for cancer cell survival at low extracellular pH.

Johanna Michl, Yunyi Wang, Stefania Monterisi, Wiktoria Blaszczak, Ryan Beveridge, Esther M Bridges, Jana Koth, Walter F Bodmer, Pawel Swietach.

DOI: https://doi.org/10.1016/j.celrep.2024.114499
PLoS Biol. 2024 Jul;22(7): e3002671

Beyond fission and fusion-Diving into the mysteries of mitochondrial shape.

Noga Preminger, Maya Schuldiner.

Mitochondrial shape and network formation have been primarily associated with the well-established processes of fission and fusion. However, recent research has unveiled an intricate and multifaceted landscape of mitochondrial morphology that extends far beyond the conventional fission-fusion paradigm. These less-explored dimensions harbor numerous unresolved mysteries. This review navigates through diverse processes influencing mitochondrial shape and network formation, highlighting the intriguing complexities and gaps in our understanding of mitochondrial architecture. The exploration encompasses various scales, from biophysical principles governing membrane dynamics to molecular machineries shaping mitochondria, presenting a roadmap for future research in this evolving field.

DOI: https://doi.org/10.1371/journal.pbio.3002671