bims-mibica 2024-12-15 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024–12–15
eleven papers selected by
Kelsey Fisher-Wellman, Wake Forest University

Autophagy inhibition induces AML cell death and enhances the efficacy of chemotherapy under hypoxia.
Exogenous expression of ATP8, a mitochondrial encoded protein, from the nucleus in vivo.
Dephosphorylation of branched-chain α-keto acid dehydrogenase E1α (BCKDHA) promotes branched-chain amino acid catabolism and renders cancer cells resistant to X-rays by mitigating DNA damage.
Carnitine palmitoyltransferase 1 facilitates fatty acid oxidation in a non-cell-autonomous manner.
Inhibition of the PI3K-AKT-MTORC1 axis reduces the burden of the m.3243A>G mtDNA mutation by promoting mitophagy and improving mitochondrial function.
Phosphorylation of Optineurin by protein kinase D regulates Parkin-dependent mitophagy.
Depleting chemoresponsive mitochondrial fission mediator DRP1 does not mitigate sarcoma resistance.
Nutrient-driven histone code determines exhausted CD8+ T cell fates.
Reactive oxygen species control protein degradation at the mitochondrial import gate.
Cu in cancer metabolism.
Pleiotropic anti-cancer activities of novel non-covalent thioredoxin reductase inhibitors against triple negative breast cancer.

bioRxiv. 2024 Nov 26. pii: 2024.11.24.625107. [Epub ahead of print]

Autophagy inhibition induces AML cell death and enhances the efficacy of chemotherapy under hypoxia.

Eunice S Wang, Hannah R S Fay, Kaitlyn M Dykstra, Michael N Phelps, Matthew Johnson, Annemarie Harrigan, Marianna C Giorgi.

Outcomes of relapsed/refractory acute myeloid leukemia (AML) are poor, and strategies to improve outcomes are urgently needed. One important factor promoting relapse and chemoresistance is the ability of AML cells to thrive in vivo within an intrinsically hypoxic bone marrow microenvironment. Here we show that human AML cells exhibit enhanced autophagy, specifically mitophagy (i.e., increased accumulation of mitochondria and decreased mitochondrial membrane potential) under hypoxia. To target this pathway, we investigated the activity of the potent chloroquine-derived autophagy inhibitor, Lys05, on human AML cells, patient samples, and patient derived xenograft models. Inhibition of autophagy by Lys05 in AML cells prevented removal of damaged mitochondria and preferentially enhanced cell death under hypoxia mirroring the marrow microenvironment. Lys05 eradicated human AML cells of all genotypes including p53 mutant cells. Lys05 treatment in primary AML xenografted mice decreased CD34+CD38- human cells and prolonged overall survival. Moreover, Lys05 overcame hypoxia-induced chemoresistance and improved the efficacy of cytarabine, venetoclax, and azacytidine in vitro and in vivo in AML models. Our results demonstrate the importance of autophagy, specifically mitophagy, as a critical survival and chemoresistance mechanism of AML cells under hypoxic marrow conditions. Therapeutic targeting of this pathway in future clinical studies for AML is warranted.

DOI: https://doi.org/10.1101/2024.11.24.625107
Mol Ther Methods Clin Dev. 2024 Dec 12. 32(4): 101372

Exogenous expression of ATP8, a mitochondrial encoded protein, from the nucleus in vivo.

David V Begelman, Bhavna Dixit, Carly Truong, Christina D King, Mark A Watson, Birgit Schilling, Martin D Brand, Amutha Boominathan.

  Replicative errors, inefficient repair, and proximity to sites of reactive oxygen species production make mitochondrial DNA (mtDNA) susceptible to damage with time. We explore in vivo allotopic expression (re-engineering mitochondrial genes and expressing them from the nucleus) as an approach to rescue defects arising from mtDNA mutations. We used a mouse strain C57BL/6J(mtFVB) with a natural polymorphism (m.7778 G>T) in the mitochondrial ATP8 gene that encodes a protein subunit of the ATP synthase. We generated a transgenic mouse with an epitope-tagged recoded mitochondrial-targeted ATP8 gene expressed from the ROSA26 locus in the nucleus and used the C57BL/6J(mtFVB) strain to verify successful incorporation. The allotopically expressed ATP8 protein in transgenic mice was constitutively expressed across all tested tissues, successfully transported into the mitochondria, and incorporated into ATP synthase. The ATP synthase with transgene had similar activity to non-transgenic control, suggesting successful integration and function. Exogenous ATP8 protein had no negative impact on measured mitochondrial function, metabolism, or behavior. Successful allotopic expression of a mitochondrially encoded protein in vivo in a mammal is a step toward utilizing allotopic expression as a gene therapy in humans to repair physiological consequences of mtDNA defects that may accumulate in congenital mitochondrial diseases or with age.

Keywords:  ATP8 gene; allotopic expression; in vivo gene therapy; mitochondrial DNA mutation; mtDNA; safe harbor expression; transgenic mouse

DOI:  https://doi.org/10.1016/j.omtm.2024.101372
Biochem Biophys Res Commun. 2024 Dec 05. pii: S0006-291X(24)01690-5. [Epub ahead of print]742 151154

Dephosphorylation of branched-chain α-keto acid dehydrogenase E1α (BCKDHA) promotes branched-chain amino acid catabolism and renders cancer cells resistant to X-rays by mitigating DNA damage.

Tomoki Bo, Tsukasa Osaki, Junichi Fujii.

  Branched-chain amino acids (BCAAs) facilitate cancer cell proliferation and survival. Stresses, including X-irradiation, increase BCAA uptake. However, the role of BCAA metabolism in cancer cell survival remains unclear. Therefore, this study aimed to elucidate the role of the BCAA catabolic pathway in cancer cell survival following X-irradiation. X-irradiation dose-dependently dephosphorylated branched-chain α-keto acid dehydrogenaseE1α (BCKDHA) suggesting the activation of the BCKDH complex, which catalyzes the rate-determining step of BCAA catabolism. We considered that activation of BCKDH promoted the BCAA catabolism, which resulted in cancer cell resistance to X-irradiation. Consistent with this notion, cells with BCKDHA knockdown exhibited increased radiosensitivity, which was associated with the increase in mitotic catastrophe and residual double-strand breaks by decreasing cellular ATP levels after X-irradiation. Our results suggest that BCKDHA dephosphorylation promotes BCAA catabolism, leading to cell survival by mitigating DNA damage after X-irradiation. Thus, BCAA catabolic pathway may be a target for radiation therapy.

Keywords:  BCAA; BCKDHA phosphorylation; Cancer; Metabolism; Radiation

DOI:  https://doi.org/10.1016/j.bbrc.2024.151154
Cell Rep. 2024 Dec 12. pii: S2211-1247(24)01357-3. [Epub ahead of print]43(12): 115006

Carnitine palmitoyltransferase 1 facilitates fatty acid oxidation in a non-cell-autonomous manner.

Joseph Choi, Danielle M Smith, Susanna Scafidi, Ryan C Riddle, Michael J Wolfgang.

  Mitochondrial fatty acid oxidation is facilitated by the combined activities of carnitine palmitoyltransferase 1 (Cpt1) and Cpt2, which generate and utilize acylcarnitines, respectively. We compare the response of mice with liver-specific deficiencies in the liver-enriched Cpt1a or the ubiquitously expressed Cpt2 and discover that they display unique metabolic, physiological, and molecular phenotypes. The loss of Cpt1a or Cpt2 results in the induction of the muscle-enriched isoenzyme Cpt1b in hepatocytes in a Pparα-dependent manner. However, hepatic Cpt1b does not contribute substantively to hepatic fatty acid oxidation when Cpt1a is absent. Liver-specific double knockout of Cpt1a and Cpt1b or Cpt2 eliminates the mitochondrial oxidation of non-esterified fatty acids. However, Cpt1a/Cpt1b double knockout mice retain fatty acid oxidation by utilizing extracellular long-chain acylcarnitines that are dependent on Cpt2. These data demonstrate the non-cell-autonomous intercellular metabolism of fatty acids in hepatocytes.

Keywords:  CP: Metabolism; Cpt1; Cpt2; acylcarnitine; biochemistry; fasting; liver; metabolism

DOI:  https://doi.org/10.1016/j.celrep.2024.115006
Autophagy. 2024 Dec 12. 1-16

Inhibition of the PI3K-AKT-MTORC1 axis reduces the burden of the m.3243A>G mtDNA mutation by promoting mitophagy and improving mitochondrial function.

Chih-Yao Chung, Kritarth Singh, Preethi Sheshadri, Gabriel E Valdebenito, Anitta R Chacko, María Alicia Costa Besada, Xiao Fei Liang, Lida Kabir, Robert D S Pitceathly, Gyorgy Szabadkai, Michael R Duchen.

  Mitochondrial DNA (mtDNA) encodes genes essential for oxidative phosphorylation. The m.3243A>G mutation causes severe disease, including myopathy, lactic acidosis and stroke-like episodes (MELAS) and is the most common pathogenic mtDNA mutation in humans. We have previously shown that the mutation is associated with constitutive activation of the PI3K-AKT-MTORC1 axis. Inhibition of this pathway in patient fibroblasts reduced the mutant load, rescued mitochondrial bioenergetic function and reduced glucose dependence. We have now investigated the mechanisms that select against the mutant mtDNA under these conditions. Basal macroautophagy/autophagy and lysosomal degradation of mitochondria were suppressed in the mutant cells. Pharmacological inhibition of any step of the PI3K-AKT-MTORC1 pathway activated mitophagy and progressively reduced m.3243A>G mutant load over weeks. Inhibition of autophagy with bafilomycin A1 or chloroquine prevented the reduction in mutant load, suggesting that mitophagy was necessary to remove the mutant mtDNA. Inhibition of the pathway was associated with metabolic remodeling - mitochondrial membrane potential and respiratory rate improved even before a measurable fall in mutant load and proved crucial for mitophagy. Thus, maladaptive activation of the PI3K-AKT-MTORC1 axis and impaired autophagy play a major role in shaping the presentation and progression of disease caused by the m.3243A>G mutation. Our findings highlight a potential therapeutic target for this otherwise intractable disease.Abbreviation: ΔΨm: mitochondrial membrane potential; 2DG: 2-deoxy-D-glucose; ANOVA: analysis of variance; ARMS-qPCR: amplification-refractory mutation system quantitative polymerase chain reaction; Baf A1: bafilomycin A1; BSA: bovine serum albumin; CQ: chloroquine; Cybrid: cytoplasmic hybrid; CYCS: cytochrome c, somatic; DCA: dichloroacetic acid; DMEM: Dulbecco's modified Eagle's medium; DMSO: dimethylsulfoxide; EGFP: enhanced green fluorescent protein; LC3B-I: carboxy terminus cleaved microtubule-associated protein 1 light chain 3 beta; LC3B-II: lipidated microtubule-associated protein 1 light chain 3 beta; LY: LY290042; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MELAS: mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes; MFC: mitochondrial fragmentation count; mt-Keima: mitochondrial-targeted mKeima; mtDNA: mitochondrial DNA/mitochondrial genome; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; OA: oligomycin+antimycin A; OxPhos: oxidative phosphorylation; DPBS: Dulbecco's phosphate-buffered saline; PPARGC1A/PGC-1α: PPARG coactivator 1 alpha; PPARGC1B/PGC-1β: PPARG coactivator 1 beta; PI3K: phosphoinositide 3-kinase; PINK1: PTEN induced kinase 1; qPCR: quantitative polymerase chain reaction; RNA-seq: RNA sequencing; RP: rapamycin; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; WT: wild-type.

Keywords:  PI3K-AKT-MTORC1; m.3243A>G; mitochondria; mitophagy; mtDNA mutations; nutrient signaling

DOI:  https://doi.org/10.1080/15548627.2024.2437908
iScience. 2024 Dec 20. 27(12): 111384

Phosphorylation of Optineurin by protein kinase D regulates Parkin-dependent mitophagy.

Robert Weil, Emmanuel Laplantine, Messaouda Attailia, Anne Oudin, Shannel Curic, Aya Yokota, Elie Banide, Pierre Génin.

  Degradation of damaged mitochondria, a process called mitophagy, plays a role in mitochondrial quality control and its dysfunction has been linked to neurodegenerative pathologies. The PINK1 kinase and the ubiquitin ligase Parkin-mediated mitophagy represents the most common pathway in which specific receptors, including Optineurin (Optn), target ubiquitin-labeled mitochondria to autophagosomes. Here, we show that Protein Kinases D (PKD) are activated and recruited to damaged mitochondria. Subsequently, PKD phosphorylate Optn to promote a complex with Parkin leading to enhancement of its ubiquitin ligase activity. Paradoxically, inhibiting PKD activity enhances the interaction between Optn and LC3, promotes the recruitment of Parkin to mitochondria, and increases the mitophagic function of Optn. This enhancement of mitophagy is characterized by increased production of mitochondrial ROS and a reduction in mitochondrial mass. The PKD kinases may therefore regulate Optn-dependent mitophagy by amplifying the Parkin-mediated degradation signals to improve the cell response against oxidative stress damage.

Keywords:  Cell biology; Molecular biology

DOI:  https://doi.org/10.1016/j.isci.2024.111384
Life Sci Alliance. 2025 Feb;pii: e202402870. [Epub ahead of print]8(2):

Depleting chemoresponsive mitochondrial fission mediator DRP1 does not mitigate sarcoma resistance.

Karolina Borankova, Matyas Solny, Maria Krchniakova, Jan Skoda.

Specific patterns of mitochondrial dynamics have been repeatedly reported to promote drug resistance in cancer. However, whether targeting mitochondrial fission- and fusion-related proteins could be leveraged to combat multidrug-resistant pediatric sarcomas is poorly understood. Here, we demonstrated that the expression and activation of the mitochondrial fission mediator DRP1 are affected by chemotherapy exposure in common pediatric sarcomas, namely, rhabdomyosarcoma and osteosarcoma. Unexpectedly, decreasing DRP1 activity through stable DRP1 knockdown neither attenuated sarcoma drug resistance nor affected growth rate or mitochondrial network morphology. The minimal impact on sarcoma cell physiology, along with the up-regulation of fission adaptor proteins (MFF and FIS1) detected in rhabdomyosarcoma cells, suggests an alternative DRP1-independent mitochondrial fission mechanism that may efficiently compensate for the lack of DRP1 activity. By exploring the upstream mitophagy and mitochondrial fission regulator, AMPKα1, we found that markedly reduced AMPKα1 levels are sufficient to maintain AMPK signaling capacity without affecting chemosensitivity. Collectively, our findings challenge the direct involvement of DRP1 in pediatric sarcoma drug resistance and highlight the complexity of yet-to-be-characterized noncanonical regulators of mitochondrial dynamics.

DOI: https://doi.org/10.26508/lsa.202402870
Science. 2024 Dec 12. eadj3020

Nutrient-driven histone code determines exhausted CD8+ T cell fates.

Shixin Ma, Michael S Dahabieh, Thomas H Mann, Steven Zhao, Bryan McDonald, Won-Suk Song, H Kay Chung, Yagmur Farsakoglu, Lizmarie Garcia-Rivera, Filipe Araujo Hoffmann, Shihao Xu, Victor Y Du, Dan Chen, Jesse Furgiuele, Michael LaPorta, Emily Jacobs, Lisa M DeCamp, Brandon M Oswald, Ryan D Sheldon, Abigail E Ellis, Longwei Liu, Peixiang He, Yingxiao Wang, Cholsoon Jang, Russell G Jones, Susan M Kaech.

Exhausted T cells (TEX) in cancer and chronic viral infections undergo metabolic and epigenetic remodeling, impairing their protective capabilities. However, the impact of nutrient metabolism on epigenetic modifications that control TEX differentiation remains unclear. We showed that TEX cells shifted from acetate to citrate metabolism by downregulating acetyl-CoA synthetase 2 (ACSS2) while maintaining ATP-citrate lyase (ACLY) activity. This metabolic switch increased citrate-dependent histone acetylation, mediated by histone acetyltransferase KAT2A-ACLY interactions, at TEX signature-genes while reducing acetate-dependent histone acetylation, dependent on p300-ACSS2 complexes, at effector and memory T cell genes. Nuclear ACSS2 overexpression or ACLY inhibition prevented TEX differentiation and enhanced tumor-specific T cell responses. These findings unveiled a nutrient-instructed histone code governing CD8+ T cell differentiation, with implications for metabolic- and epigenetic-based T cell therapies.

DOI: https://doi.org/10.1126/science.adj3020
Mol Cell. 2024 Dec 05. pii: S1097-2765(24)00909-2. [Epub ahead of print]84(23): 4612-4628.e13

Reactive oxygen species control protein degradation at the mitochondrial import gate.

Rachael McMinimy, Andrew G Manford, Christine L Gee, Srividya Chandrasekhar, Gergey Alzaem Mousa, Joelle Chuang, Lilian Phu, Karen Y Shih, Christopher M Rose, John Kuriyan, Baris Bingol, Michael Rapé.

  While reactive oxygen species (ROS) have long been known to drive aging and neurodegeneration, their persistent depletion below basal levels also disrupts organismal function. Cells counteract loss of basal ROS via the reductive stress response, but the identity and biochemical activity of ROS sensed by this pathway remain unknown. Here, we show that the central enzyme of the reductive stress response, the E3 ligase Cullin 2-FEM1 homolog B (CUL2FEM1B), specifically acts at mitochondrial TOM complexes, where it senses ROS produced by complex III of the electron transport chain (ETC). ROS depletion during times of low ETC activity triggers the localized degradation of CUL2FEM1B substrates, which sustains mitochondrial import and ensures the biogenesis of the rate-limiting ETC complex IV. As complex III yields most ROS when the ETC outpaces metabolic demands or oxygen availability, basal ROS are sentinels of mitochondrial activity that help cells adjust their ETC to changing environments, as required for cell differentiation and survival.

Keywords:  FEM1B; TOM complex; electron transport chain; mitochondria; proteasome; reductive stress response; ubiquitin

DOI:  https://doi.org/10.1016/j.molcel.2024.11.004
Nat Cell Biol. 2024 Dec;26(12): 2013

Cu in cancer metabolism.

Zhe Wang.

DOI: https://doi.org/10.1038/s41556-024-01578-6
Free Radic Biol Med. 2024 Dec 04. pii: S0891-5849(24)01108-0. [Epub ahead of print]227 201-209

Pleiotropic anti-cancer activities of novel non-covalent thioredoxin reductase inhibitors against triple negative breast cancer.

Brenna Flowers, Abigail Rullo, An Zhang, Keacha Chang, Valentina Z Petukhova, Sammy Y Aboagye, Francesco Angelucci, David L Williams, Steven Kregel, Pavel A Petukhov, Irida Kastrati.

Mounting evidence shows that tumor growth and progression rely on thioredoxin reductase 1 (TXNRD1)-mediated detoxification of oxidative stress that results from deregulated metabolism and mitogenic signaling in tumors. TXNRD1 levels are significant higher in triple negative breast cancer (TNBC) compared to normal tissue, making TXNRD1 a compelling TNBC therapeutic target. Despite the many attempts to generate TXNRD1 inhibitors, all known and reported compounds inhibiting TXNRD1 are problematic; they interact with TXNRD1 irreversibly and non-specifically resulting in numerous adverse side effects. Recently, a series of breakthrough studies identified a novel regulatory site, the 'doorstop pocket', in Schistosoma mansoni thioredoxin glutathione reductase, a TXNRD-like enzyme and an established drug target for the human parasitic infection, schistosomiasis. This discovery underpins the development of new first-in-class non-covalent inhibitors for this family of enzymes. Our data show that novel non-covalent TXNRD inhibitors (TXNRD(i)s) are potent dose-dependent inhibitors of viability in cellular models of TNBC. TXNRD(i)s attenuate several aggressive cancer phenotypes such as, clonogenic survival, mammosphere forming efficiency, invasion, and TXNRD-related gene expression in TNBC cells. TXNRD(i)s engage and inhibit TXNRD1 in live TNBC cells and xenograft tumors, thus supporting the mechanism of action at a cellular level. More importantly, TXNRD(i)s attenuated tumor growth in a preclinical MDA-MB-231 TNBC xenograft mouse model. Although additional optimization for TXNRD(i)s' potency is warranted, these results may open a new avenue for the development of novel small molecule therapeutics for TNBC.

DOI: https://doi.org/10.1016/j.freeradbiomed.2024.12.010