bims-mibica 2022-02-06 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2022–02–06
38 papers selected by
Kelsey Fisher-Wellman, East Carolina University

Suppression of NSCLC A549 tumor growth by a mtDNA mutation-targeting pyrrole-imidazole polyamide-TPP and a senolytic drug.
Proline synthesis through PYCR1 is required to support cancer cell proliferation and survival in oxygen-limiting conditions.
The cardiac-enriched microprotein mitolamban regulates mitochondrial respiratory complex assembly and function in mice.
Assembly-dependent translation of subunits 6 (Atp6) and 9 (Atp9) of ATP synthase in yeast mitochondria.
Mitochondrial inhibitors circumvent adaptive resistance to venetoclax and cytarabine combination therapy in acute myeloid leukemia.
mtDNA mutations help support cancer cells.
ATAD3A mediates activation of RAS-independent mitochondrial ERK1/2 signaling, favoring head and neck cancer development.
Complexome Profiling-Exploring Mitochondrial Protein Complexes in Health and Disease.
Alteration of mitochondrial protein succinylation against cellular oxidative stress in cancer.
Protocols for analyzing metabolic derangements caused by increased NADH/NAD+ ratio in cell lines and in mice.
Disrupted Liver Oxidative Metabolism in Glycine N-Methyltransferase-Deficient Mice is Mitigated by Dietary Methionine Restriction.
Mitochondrial protein import determines lifespan through metabolic reprogramming and de novo serine biosynthesis.
Platelet-derived respiratory-competent mitochondria transfer to mesenchymal stem cells to promote wound healing via metabolic reprogramming.
ApoE4 confers mitochondrial substrate oxidation defects that can be bioenergetically compensated by a ketogenic substrate beta-hydroxy butyrate (BHB).
Mitochondrial respiratory chain dysfunction alters ER sterol sensing and mevalonate pathway activity.
Synthetic adiponectin-receptor agonist, AdipoRon, induces glycolytic dependence in pancreatic cancer cells.
Mitochondrial Creatine Kinase Attenuates Pathologic Remodeling in Heart Failure.
TAZ links exercise to mitochondrial biogenesis via mitochondrial transcription factor A.
The effects of hypoxia on mitochondrial function and metabolism in gastric cancer cells.
Selective vulnerabilities in the proteostasis network of castration-resistant prostate cancer.
In-cytoplasm mitochondrial transplantation for mesenchymal stem cells engineering and tissue regeneration.
Yme2, a putative RNA recognition motif and AAA+ domain containing protein, genetically interacts with the mitochondrial protein export machinery.
CDK19 regulates the proliferation of hematopoietic stem cells and acute myeloid leukemia cells by suppressing p53-mediated transcription of p21.
Loss of TET reprograms Wnt signaling through impaired demethylation to promote lung cancer development.
Elevated expression of mitochondrial transcription elongation factor (TEFM) predicts poor prognosis in low grade glioma-an analysis of the Cancer Genome Atlas (TCGA) dataset.
Aldolase B suppresses hepatocellular carcinogenesis by inhibiting G6PD and pentose phosphate pathways.
NR2F2 controls malignant squamous cell carcinoma state by promoting stemness and invasion and repressing differentiation.
Chemical augmentation of mitochondrial electron transport chains tunes T cell activation threshold in tumors.
Mitochondrial respiration of human platelets in young adult and advanced age - Seahorse or O2k?
Comparison of mitochondrial DNA sequences from whole blood and lymphoblastoid cell lines.
Albumin binds to uncoupler CCCP to diminish depolarization of mitochondria.
Diet-derived ergothioneine induces necroptosis in colorectal cancer cells by activating the SIRT3/MLKL pathway.
APOBEC3A drives deaminase domain-independent chromosomal instability to promote pancreatic cancer metastasis.
The mouse metallomic landscape of aging and metabolism.
Loss of glucose 6-phosphate dehydrogenase function increases oxidative stress and glutaminolysis in metastasizing melanoma cells.
Impaired mitochondrial ATP production, reduced mitochondrial spare respiratory capacity, and increased oxidative stress in PBMCs are associated with aging in adult EGAT population.
Cooperation among c-subunits of FoF1-ATP synthase in rotation-coupled proton translocation.
Photo-activation of mitochondrial ATP synthesis.

Cancer Sci. 2022 Feb 02.

Suppression of NSCLC A549 tumor growth by a mtDNA mutation-targeting pyrrole-imidazole polyamide-TPP and a senolytic drug.

Kohei Tsuji, Yuki Kida, Nobuko Koshikawa, Seigi Yamamoto, Yoshinao Shinozaki, Takayoshi Watanabe, Jason Lin, Hiroki Nagase, Keizo Takenaga.

  Certain somatic mutations in mitochondrial DNA (mtDNA) were associated with tumor progression and frequently found in a homoplasmic state. We recently reported that pyrrole-imidazole polyamide conjugated with the mitochondria-delivering moiety triphenylphosphonium (PIP-TPP) targeting a mtDNA mutation efficiently induced apoptosis in cancer cells with the mutation but not normal cells. Here, we synthesized the novel PIP-TPP, CCC-021-TPP, targeting ND6 14582A>G homoplasmic missense mutation that is suggested to enhance metastasis of NSCLC A549 cells. CCC-021-TPP did not induce apoptosis but caused cellular senescence in the cells, accompanied by a significant induction of antiapoptotic BCL-XL. Simultaneous treatment of A549 cells with CCC-021-TPP and the BCL-XL selective inhibitor A-1155463 resulted in apoptosis induction. Importantly, the combination induced apoptosis and suppressed tumor growth in an A549 xenografted model. These results highlight the potential of anticancer therapy with PIP-TPPs targeting mtDNA mutations to induce cell death even in apoptosis resistant cancer cells when combined with senolytics.

Keywords:  Apoptosis; Mitochondria; Mutation; Pyrrole-imidazole polyamide; mtDNA

DOI:  https://doi.org/10.1111/cas.15290
Cell Rep. 2022 Feb 01. pii: S2211-1247(22)00031-6. [Epub ahead of print]38(5): 110320

Proline synthesis through PYCR1 is required to support cancer cell proliferation and survival in oxygen-limiting conditions.

Rebecca L Westbrook, Esther Bridges, Jennie Roberts, Cristina Escribano-Gonzalez, Katherine L Eales, Lisa A Vettore, Paul D Walker, Elias Vera-Siguenza, Himani Rana, Federica Cuozzo, Kattri-Liis Eskla, Hans Vellama, Abeer Shaaban, Colin Nixon, Hendrik Luuk, Gareth G Lavery, David J Hodson, Adrian L Harris, Daniel A Tennant.

  The demands of cancer cell proliferation alongside an inadequate angiogenic response lead to insufficient oxygen availability in the tumor microenvironment. Within the mitochondria, oxygen is the major electron acceptor for NADH, with the result that the reducing potential produced through tricarboxylic acid (TCA) cycle activity and mitochondrial respiration are functionally linked. As the oxidizing activity of the TCA cycle is required for efficient synthesis of anabolic precursors, tumoral hypoxia could lead to a cessation of proliferation without another means of correcting the redox imbalance. We show that in hypoxic conditions, mitochondrial pyrroline 5-carboxylate reductase 1 (PYCR1) activity is increased, oxidizing NADH with the synthesis of proline as a by-product. We further show that PYCR1 activity is required for the successful maintenance of hypoxic regions by permitting continued TCA cycle activity, and that its loss leads to significantly increased hypoxia in vivo and in 3D culture, resulting in widespread cell death.

Keywords:  NADH; PYCR1; cancer; hypoxia; mitochondria; proline; redox

DOI:  https://doi.org/10.1016/j.celrep.2022.110320
Proc Natl Acad Sci U S A. 2022 Feb 08. pii: e2120476119. [Epub ahead of print]119(6):

The cardiac-enriched microprotein mitolamban regulates mitochondrial respiratory complex assembly and function in mice.

Catherine A Makarewich, Amir Z Munir, Svetlana Bezprozvannaya, Aaron M Gibson, Soo Young Kim, Misty S Martin-Sandoval, Thomas P Mathews, Luke I Szweda, Rhonda Bassel-Duby, Eric N Olson.

  Emerging evidence indicates that a subset of RNA molecules annotated as noncoding contain short open reading frames that code for small functional proteins called microproteins, which have largely been overlooked due to their small size. To search for cardiac-expressed microproteins, we used a comparative genomics approach and identified mitolamban (Mtlbn) as a highly conserved 47-amino acid transmembrane protein that is abundantly expressed in the heart. Mtlbn localizes specifically to the inner mitochondrial membrane where it interacts with subunits of complex III of the electron transport chain and with mitochondrial respiratory supercomplexes. Genetic deletion of Mtlbn in mice altered complex III assembly dynamics and reduced complex III activity. Unbiased metabolomic analysis of heart tissue from Mtlbn knockout mice further revealed an altered metabolite profile consistent with deficiencies in complex III activity. Cardiac-specific Mtlbn overexpression in transgenic (TG) mice induced cardiomyopathy with histological, biochemical, and ultrastructural pathologic features that contributed to premature death. Metabolomic analysis and biochemical studies indicated that hearts from Mtlbn TG mice exhibited increased oxidative stress and mitochondrial dysfunction. These findings reveal Mtlbn as a cardiac-expressed inner mitochondrial membrane microprotein that contributes to mitochondrial electron transport chain activity through direct association with complex III and the regulation of its assembly and function.

Keywords:  cardiac; microprotein; mitochondria; oxidative phosphorylation

DOI:  https://doi.org/10.1073/pnas.2120476119
Genetics. 2022 Jan 20. pii: iyac007. [Epub ahead of print]

Assembly-dependent translation of subunits 6 (Atp6) and 9 (Atp9) of ATP synthase in yeast mitochondria.

Anna M Kabala, Krishia Binko, François Godard, Camille Charles, Alain Dautant, Emilia Baranowska, Natalia Skoczen, Kewin Gombeau, Marine Bouhier, Hubert D Becker, Sharon H Ackerman, Lars M Steinmetz, Déborah Tribouillard-Tanvier, Rosa Kucharczyk, Jean-Paul di Rago.

  The yeast mitochondrial ATP synthase is an assembly of 28 subunits of 17 types of which 3 (subunits 6, 8, and 9) are encoded by mitochondrial genes while the 14 others have a nuclear genetic origin. Within the membrane domain (FO) of this enzyme, the subunit 6 and a ring of 10 identical subunits 9 transport protons across the mitochondrial inner membrane coupled to ATP synthesis in the extra-membrane structure (F1) of ATP synthase. As a result of their dual genetic origin, the ATP synthase subunits are synthesized in the cytosol and inside the mitochondrion. How they are produced in the proper stoichiometry from two different cellular compartments is still poorly understood. The experiments herein reported show that the rate of translation of the subunits 9 and 6 is enhanced in strains with mutations leading to specific defects in the assembly of these proteins. These translation modifications involve assembly intermediates interacting with subunits 6 and 9 within the final enzyme and cis-regulatory sequences that control gene expression in the organelle. In addition to enabling a balanced output of the ATP synthase subunits, these assembly-dependent feedback loops are presumably important to limit the accumulation of harmful assembly intermediates that have the potential to dissipate the mitochondrial membrane electrical potential and the main source of chemical energy of the cell.

Keywords:  ATP synthase; Mitochondria; Mitochondria DNA; Mitochondrial biogenesis; Mitochondrial gene expression; yeast

DOI:  https://doi.org/10.1093/genetics/iyac007
Nat Cancer. 2021 Nov;2(11): 1204-1223

Mitochondrial inhibitors circumvent adaptive resistance to venetoclax and cytarabine combination therapy in acute myeloid leukemia.

Claudie Bosc, Estelle Saland, Aurélie Bousard, Noémie Gadaud, Marie Sabatier, Guillaume Cognet, Thomas Farge, Emeline Boet, Mathilde Gotanègre, Nesrine Aroua, Pierre-Luc Mouchel, Nathaniel Polley, Clément Larrue, Eléonore Kaphan, Muriel Picard, Ambrine Sahal, Latifa Jarrou, Marie Tosolini, Florian Rambow, Florence Cabon, Nathalie Nicot, Laura Poillet-Perez, Yujue Wang, Xiaoyang Su, Quentin Fovez, Jérôme Kluza, Rafael José Argüello, Céline Mazzotti, Hervé Avet-Loiseau, François Vergez, Jérôme Tamburini, Jean-Jacques Fournié, Ing S Tiong, Andrew H Wei, Tony Kaoma, Jean-Christophe Marine, Christian Récher, Lucille Stuani, Carine Joffre, Jean-Emmanuel Sarry.

Therapy resistance represents a major clinical challenge in acute myeloid leukemia (AML). Here we define a 'MitoScore' signature, which identifies high mitochondrial oxidative phosphorylation in vivo and in patients with AML. Primary AML cells with cytarabine (AraC) resistance and a high MitoScore relied on mitochondrial Bcl2 and were highly sensitive to venetoclax (VEN) + AraC (but not to VEN + azacytidine). Single-cell transcriptomics of VEN + AraC-residual cell populations revealed adaptive resistance associated with changes in oxidative phosphorylation, electron transport chain complex and the TP53 pathway. Accordingly, treatment of VEN + AraC-resistant AML cells with electron transport chain complex inhibitors, pyruvate dehydrogenase inhibitors or mitochondrial ClpP protease agonists substantially delayed relapse following VEN + AraC. These findings highlight the central role of mitochondrial adaptation during AML therapy and provide a scientific rationale for alternating VEN + azacytidine with VEN + AraC in patients with a high MitoScore and to target mitochondrial metabolism to enhance the sensitivity of AML cells to currently approved therapies.

DOI: https://doi.org/10.1038/s43018-021-00264-y
Nat Cancer. 2020 Oct;1(10): 941-942

mtDNA mutations help support cancer cells.

Hiran A Prag, Michael P Murphy.

DOI: https://doi.org/10.1038/s43018-020-00128-x
J Exp Clin Cancer Res. 2022 Jan 29. 41(1): 43

ATAD3A mediates activation of RAS-independent mitochondrial ERK1/2 signaling, favoring head and neck cancer development.

Liwei Lang, Reid Loveless, Juan Dou, Tiffany Lam, Alex Chen, Fang Wang, Li Sun, Jakeline Juarez, Zhaohui Steve Qin, Nabil F Saba, Chloe Shay, Yong Teng.

   BACKGROUND: Targeting mitochondrial oncoproteins presents a new concept in the development of effective cancer therapeutics. ATAD3A is a nuclear-encoded mitochondrial enzyme contributing to mitochondrial dynamics, cholesterol metabolism, and signal transduction. However, its impact and underlying regulatory mechanisms in cancers remain ill-defined.
METHODS: We used head and neck squamous cell carcinoma (HNSCC) as a research platform and achieved gene depletion by lentiviral shRNA and CRISPR/Cas9. Molecular alterations were examined by RNA-sequencing, phospho-kinase profiling, Western blotting, RT-qPCR, immunohistochemistry, and immunoprecipitation. Cancer cell growth was assessed by MTT, colony formation, soft agar, and 3D cultures. The therapeutic efficacy in tumor development was evaluated in orthotopic tongue tumor NSG mice.
RESULTS: ATAD3A is highly expressed in HNSCC tissues and cell lines. Loss of ATAD3A expression suppresses HNSCC cell growth and elicits tumor regression in orthotopic tumor-bearing mice, whereas gain of ATAD3A expression produces the opposite effects. From a mechanistic perspective, the tumor suppression induced by the overexpression of the Walker A dead mutant of ATAD3A (K358) produces a potent dominant-negative effect due to defective ATP-binding. Moreover, ATAD3A binds to ERK1/2 in the mitochondria of HNSCC cells in the presence of VDAC1, and this interaction is essential for the activation of mitochondrial ERK1/2 signaling. Most importantly, the ATAD3A-ERK1/2 signaling axis drives HNSCC development in a RAS-independent fashion and, thus, tumor suppression is more effectively achieved when ATAD3A knockout is combined with RAS inhibitor treatment.
CONCLUSIONS: These findings highlight the novel function of ATAD3A in regulating mitochondrial ERK1/2 activation that favors HNSCC development. Combined targeting of ATAD3A and RAS signaling may potentiate anticancer activity for HNSCC therapeutics.

Keywords:  ATAD3A; HNSCC; Mitochondrial ERK1/2; RAS; VDAC1; WA dead mutant

DOI:  https://doi.org/10.1186/s13046-022-02274-9
Front Cell Dev Biol. 2021 ;9 796128

Complexome Profiling-Exploring Mitochondrial Protein Complexes in Health and Disease.

Alfredo Cabrera-Orefice, Alisa Potter, Felix Evers, Johannes F Hevler, Sergio Guerrero-Castillo.

  Complexome profiling (CP) is a state-of-the-art approach that combines separation of native proteins by electrophoresis, size exclusion chromatography or density gradient centrifugation with tandem mass spectrometry identification and quantification. Resulting data are computationally clustered to visualize the inventory, abundance and arrangement of multiprotein complexes in a biological sample. Since its formal introduction a decade ago, this method has been mostly applied to explore not only the composition and abundance of mitochondrial oxidative phosphorylation (OXPHOS) complexes in several species but also to identify novel protein interactors involved in their assembly, maintenance and functions. Besides, complexome profiling has been utilized to study the dynamics of OXPHOS complexes, as well as the impact of an increasing number of mutations leading to mitochondrial disorders or rearrangements of the whole mitochondrial complexome. Here, we summarize the major findings obtained by this approach; emphasize its advantages and current limitations; discuss multiple examples on how this tool could be applied to further investigate pathophysiological mechanisms and comment on the latest advances and opportunity areas to keep developing this methodology.

Keywords:  complexome profiling; disease; mass spectrometry; mitochondria; oxidative phosphorylation; protein complex; protein-protein interaction (PPI); proteomics

DOI:  https://doi.org/10.3389/fcell.2021.796128
Mil Med Res. 2022 Feb 04. 9(1): 6

Alteration of mitochondrial protein succinylation against cellular oxidative stress in cancer.

Jing Zhang, Zi-Qin Han, Yang Wang, Qing-Yu He.



Keywords:  Glutaminase; Mitochondria; Phosphorylation; Succinylation

DOI:  https://doi.org/10.1186/s40779-022-00367-2
STAR Protoc. 2022 Mar 18. 3(1): 101120

Protocols for analyzing metabolic derangements caused by increased NADH/NAD+ ratio in cell lines and in mice.

Shanshan Liu, Yan Ma, Hui Jiang.

  Mitochondrial electron transport chain (ETC) dysfunction elevates the NADH/NAD+ ratio to cause metabolic derangements. Here we describe a protocol to measure the NADH/NAD+ ratio and analyze the rewiring of glucose metabolism using [4-2H]-glucose, [3-2H]-glucose, and [U-13C]-glucose in ETC-inhibited human cancer cells. We also describe a protocol to analyze the NADH/NAD+ ratio-sensitive metabolites in mouse plasma and mouse liver following phenformin treatment. These protocols comprehensively analyze the metabolic derangements resulting from increased NADH/NAD+ ratio in in vitro and in vivo models. For complete details on the use and execution of this profile, please refer to Liu et al. (2021).

Keywords:  Cell Biology; Cell culture; Cell-based Assays; Mass Spectrometry; Metabolism; Model Organisms

DOI:  https://doi.org/10.1016/j.xpro.2021.101120
Mol Metab. 2022 Feb 01. pii: S2212-8778(22)00021-7. [Epub ahead of print] 101452

Disrupted Liver Oxidative Metabolism in Glycine N-Methyltransferase-Deficient Mice is Mitigated by Dietary Methionine Restriction.

Ferrol I Rome, Curtis C Hughey.

   OBJECTIVE: One-carbon metabolism is routinely dysregulated in nonalcoholic fatty liver disease. This includes decreased glycine N-methyltransferase (GNMT), a critical regulator of s-adenosylmethionine (SAM). Deletion of GNMT in mice increases SAM and promotes liver steatosis. Lower liver oxidative metabolism as indicated by a decline in gluconeogenesis, citric acid cycle flux, and oxidative phosphorylation contributes to liver steatosis in GNMT-null mice, however, the extent to which this phenotype is mediated by higher SAM remains unclear. Here, we determined the SAM-dependent impairment in liver oxidative metabolism by loss of GNMT.
METHODS: GNMT knockout (KO) mice were fed a methionine-restricted diet to prevent increased SAM. 2H/13C metabolic flux analysis was performed in conscious, unrestrained mice to quantify liver nutrient fluxes. Metabolomics and high-resolution respirometry was used to quantify liver nutrient pool sizes and mitochondrial oxidative phosphorylation, respectively. Folic acid-supplemented and serine/glycine-deficient diets were used independently to further define the metabolic implications of perturbed one-carbon donor availability.
RESULTS: Dietary methionine restriction prevented a 75-fold increase in SAM and 53% rise in triacylglycerides in livers of KO mice. Dietary methionine restriction increased gluconeogenesis independent of genotype and restored cytochrome c oxidase respiratory function in KO mice. Citric acid cycle fluxes remained lower in KO mice irrespective of diet. Restricting dietary methionine abrogated markers of increased lipogenesis and folate cycle dysfunction in KO mice.
CONCLUSION: The impaired liver oxidative metabolism following loss of GNMT is both dependent and independent of greater SAM availability. Lower in vivo citric acid cycle flux is independent of increased SAM. In contrast, gluconeogenesis and oxidative phosphorylation are negatively regulated by excess SAM. Lipid accumulation in livers of mice lacking GNMT is also linked to the higher SAM.

Keywords:  citric acid cycle; gluconeogenesis; lipogenesis; nonalcoholic fatty liver disease; one-carbon metabolism; oxidative phosphorylation

DOI:  https://doi.org/10.1016/j.molmet.2022.101452
Nat Commun. 2022 Feb 03. 13(1): 651

Mitochondrial protein import determines lifespan through metabolic reprogramming and de novo serine biosynthesis.

Eirini Lionaki, Ilias Gkikas, Ioanna Daskalaki, Maria-Konstantina Ioannidi, Maria I Klapa, Nektarios Tavernarakis.

Sustained mitochondrial fitness relies on coordinated biogenesis and clearance. Both processes are regulated by constant targeting of proteins into the organelle. Thus, mitochondrial protein import sets the pace for mitochondrial abundance and function. However, our understanding of mitochondrial protein translocation as a regulator of longevity remains enigmatic. Here, we targeted the main protein import translocases and assessed their contribution to mitochondrial abundance and organismal physiology. We find that reduction in cellular mitochondrial load through mitochondrial protein import system suppression, referred to as MitoMISS, elicits a distinct longevity paradigm. We show that MitoMISS triggers the mitochondrial unfolded protein response, orchestrating an adaptive reprogramming of metabolism. Glycolysis and de novo serine biosynthesis are causatively linked to longevity, whilst mitochondrial chaperone induction is dispensable for lifespan extension. Our findings extent the pro-longevity role of UPRmt and provide insight, relevant to the metabolic alterations that promote or undermine survival and longevity.

DOI: https://doi.org/10.1038/s41467-022-28272-1
Platelets. 2022 Feb 03. 1-3

Platelet-derived respiratory-competent mitochondria transfer to mesenchymal stem cells to promote wound healing via metabolic reprogramming.

Enlin Chen, Zhe Chen, Linxi Chen, Xiaoling Hu.

  Mitochondria regulate intracellular metabolism and are also involved in intercellular transfer in vitro and in vivo, thereby affecting the function of adjacent cells. Mitochondria can also be transferred to various differentiated cells to improve their respiratory function, ATP production, as well as protect damaged cells from apoptosis. Both in vivo and in vitro, mitochondria can be transferred from one cell to another to regulate cellular metabolism under physiological or pathophysiological conditions, referred to as "mitochondrial translocation". Mitochondrial translocation is associated in various situations such as repairing damaged cells, promoting cancer progression and enhancing chemoresistance. Platelets contain mitochondria that promote energy metabolism and various growth factors, thus playing an important role in pathophysiological processes such as thrombosis, hemostasis, inflammation and wound healing. Current studies suggest that mesenchymal stem cells (MSCs) can communicate with their microenvironment through bidirectional alternation of mitochondria to improve their wound healing capacity. Platelets or platelet-containing preparations such as platelet-rich plasma (PRP) can stimulate the proliferation and pro-angiogenic properties of MSCs under oxidative stress to enhance their survival. Recent studies by Levoux et al. have shown that activated platelet-derived mitochondria have the respiratory capacity to translocate to MSCs and stimulate the pro-angiogenic properties of MSCs through metabolic reprogramming, thereby promoting angiogenesis and wound healing. The mechanism of mitochondrial internalization of cells and energy metabolism is a new example of mitochondrial translocation altering somatic cell behavior and viability. Therefore, we aim to comment the mechanisms of platelet mitochondrial translocation and metabolic reprogramming of MSCs, suggesting that platelets or platelet-containing preparations such as platelet-rich plasma (PRP) may provide a practical guide for tissue injury treatment.

Keywords:  Mitochondria; stem cells; wound healing

DOI:  https://doi.org/10.1080/09537104.2021.1961717
Alzheimers Dement. 2021 Dec;17 Suppl 3 e054355

ApoE4 confers mitochondrial substrate oxidation defects that can be bioenergetically compensated by a ketogenic substrate beta-hydroxy butyrate (BHB).

Chase Garcia, Alexey Tomilov, Jose Sandoval, Gino A Cortopassi.

BACKGROUND: Mitochondria are at the center of neural biogenergetics, and ApoE4 is the single most impactful risk factor for AD. We investigated the impact of ApoE on insulin sensitivity, on mitochondrial substrate utilization and bioenergetics. Persons with ApoE4 have reduced brain carbohydrate metabolism. To test for ApoE4 conferred neural mitochondrial metabolic differences, we constructed a novel stable-ApoE 2,3 and 4 N2a cell model, and tested ApoE's effects on Insulin sensitivity, and mitochondrial glucose, lipid and ketone oxidation.
METHOD: Binding of ApoE isoforms E2, E3 and E4 to Insulin Receptor (IR) was measured by BLI and Co-IP, the impact of ApoE isoforms on mitochondrial glucose and lipid oxidation was measured by Seahorse.
RESULT: ApoE3 was found to sensitize to insulin about 2-fold more potently than ApoE4. ApoE isoforms directly bind Insulin Receptor; the binding constants was in the range 200-300nM. Consistent with the previous insulin-sensitivity finding, ApoE3 caused a significant increase of the glycolytic rate and glucose oxidation relative to ApoE4. As there was no difference in oxidation of TCA cycle intermediates substrates in permeabilized cells, we infer ApoE3's glucose advantage is the result of increased insulin sensitivity. ApoE4 contributed a significant palmitate oxidation defect relative to ApoE2 and ApoE3. As this palmitate oxidation defect was observed in both mitochondria and cells it is likely to occur at or within mitochondria. We observed that the relative defect in ApoE4-dependent glucose and palmitate oxidation can be overcome by 5mM BHB. Thus, at the neural cell level, the metabolic defects contributed by ApoE 4 appear to be rescued by a ketogenic molecule, BHB, that requires neither insulin nor apolipoprotein particle to reach neural mitochondria and provide alternative metabolic support.
CONCLUSION: ApoE4 confers 'double trouble' in mitochondrial glucose and lipid oxidation. ApoE4 confers a defect in mitochondrial lipid oxidation relative to all other isoforms. Simultaneously, ApoE4 lacks the benefit in glucose oxidation conferred by ApoE3, which appears to be driven by the reduced insulin sensitization potency of ApoE4. We also find that BHB can be an alternative source of neural bioenergy that enters mitochondria directly and thus is not affected by ApoE4 'double trouble'.

DOI: https://doi.org/10.1002/alz.054355
J Biol Chem. 2022 Jan 28. pii: S0021-9258(22)00092-8. [Epub ahead of print] 101652

Mitochondrial respiratory chain dysfunction alters ER sterol sensing and mevalonate pathway activity.

Christopher Tadhg James Wall, Gregory Lefebvre, Sylviane Metairon, Patrick Descombes, Andreas Wiederkehr, Jaime Santo Domingo.

  Mitochondrial dysfunction induces a strong adaptive retrograde signaling response; however, many of the down-stream effectors of this response remain to be discovered. Here, we studied the shared transcriptional responses to three different mitochondrial respiratory chain inhibitors in human primary skin fibroblasts using QuantSeq 3'-RNA-sequencing. We found that genes involved in the mevalonate pathway were concurrently downregulated, irrespective of the respiratory chain complex affected. Targeted metabolomics demonstrated that impaired mitochondrial respiration at any of the three affected complexes also had functional consequences on the mevalonate pathway, reducing levels of cholesterol precursor metabolites. A deeper study of complex I inhibition showed a reduced activity of ER-bound sterol-sensing enzymes through impaired processing of the transcription factor SREBP2 and accelerated degradation of the ER cholesterol-sensors SQLE and HMGCR. These adaptations of mevalonate pathway activity affected neither total intracellular cholesterol levels nor the cellular free (non-esterified) cholesterol pool. Finally, measurement of intracellular cholesterol using the fluorescent cholesterol binding dye filipin revealed that complex I inhibition elevated cholesterol on intracellular compartments. Taken together, our study shows that mitochondrial respiratory chain dysfunction elevates intracellular free cholesterol levels and therefore attenuates the expression of mevalonate pathway enzymes, which lowers endogenous cholesterol biosynthesis, disrupting the metabolic output of the mevalonate pathway. We conclude that intracellular disturbances in cholesterol homeostasis may alter systemic cholesterol management in diseases associated with declining mitochondrial function.

Keywords:  Cholesterol; CoQ; HMGCR; SQLE; SREBP2; farnesyl pyrophosphate; geranyl pyrophosphate; mevalonate pathway; mitochondria; retrograde signaling; sterol; ubiquinol

DOI:  https://doi.org/10.1016/j.jbc.2022.101652
Cell Death Dis. 2022 Feb 04. 13(2): 114

Synthetic adiponectin-receptor agonist, AdipoRon, induces glycolytic dependence in pancreatic cancer cells.

Sharon J Manley, Appolinaire A Olou, Jarrid L Jack, Mariana T Ruckert, R McKinnon Walsh, Austin E Eades, Bailey A Bye, Joe Ambrose, Fanuel Messaggio, Shrikant Anant, Michael N VanSaun.

Obesity creates a localized inflammatory reaction in the adipose, altering secretion of adipocyte-derived factors that contribute to pathologies including cancer. We have previously shown that adiponectin inhibits pancreatic cancer by antagonizing leptin-induced STAT3 activation. Yet, the effects of adiponectin on pancreatic cancer cell metabolism have not been addressed. In these studies, we have uncovered a novel metabolic function for the synthetic adiponectin-receptor agonist, AdipoRon. Treatment of PDAC cells with AdipoRon led to mitochondrial uncoupling and loss of ATP production. Concomitantly, AdipoRon-treated cells increased glucose uptake and utilization. This metabolic switch further correlated with AMPK mediated inhibition of the prolipogenic factor acetyl coenzyme A carboxylase 1 (ACC1), which is known to initiate fatty acid catabolism. Yet, measurements of fatty acid oxidation failed to detect any alteration in response to AdipoRon treatment, suggesting a deficiency for compensation. Additional disruption of glycolytic dependence, using either a glycolysis inhibitor or low-glucose conditions, demonstrated an impairment of growth and survival of all pancreatic cancer cell lines tested. Collectively, these studies provide evidence that pancreatic cancer cells utilize metabolic plasticity to upregulate glycolysis in order to adapt to suppression of oxidative phosphorylation in the presence of AdipoRon.

DOI: https://doi.org/10.1038/s41419-022-04572-8
Circ Res. 2022 Feb 03. CIRCRESAHA121319648

Mitochondrial Creatine Kinase Attenuates Pathologic Remodeling in Heart Failure.

Gizem Keceli, Ashish Gupta, Joevin Sourdon, Refaat Gabr, Michael Schär, Swati Dey, Carlo G Tocchetti, Annina Stuber, Jacopo Agrimi, Yi Zhang, Michelle Leppo, Charles Steenbergen, Shenghan Lai, Lisa R Yanek, Brian O'Rourke, Gary Gerstenblith, Paul A Bottomley, Yibin Wang, Nazareno Paolocci, Robert G Weiss.

   BACKGROUND: Abnormalities in cardiac energy metabolism occur in heart failure (HF) and contribute to contractile dysfunction, but their role, if any, in HF-related pathologic remodeling is much less established. CK (creatine kinase), the primary muscle energy reserve reaction which rapidly provides ATP at the myofibrils and regenerates mitochondrial ADP, is down-regulated in experimental and human HF. To test the hypotheses that pathologic remodeling in human HF is related to impaired cardiac CK energy metabolism and that rescuing CK attenuates maladaptive hypertrophy in experimental HF.
METHODS: First, in 27 HF patients and 14 healthy subjects, we measured cardiac energetics and left ventricular remodeling using noninvasive magnetic resonance 31P spectroscopy and magnetic resonance imaging, respectively. Second, we tested the impact of metabolic rescue with cardiac-specific overexpression of either Ckmyofib (myofibrillar CK) or Ckmito (mitochondrial CK) on HF-related maladaptive hypertrophy in mice.
RESULTS: In people, pathologic left ventricular hypertrophy and dilatation correlate closely with reduced myocardial ATP levels and rates of ATP synthesis through CK. In mice, transverse aortic constriction-induced left ventricular hypertrophy and dilatation are attenuated by overexpression of CKmito, but not by overexpression of CKmyofib. CKmito overexpression also attenuates hypertrophy after chronic isoproterenol stimulation. CKmito lowers mitochondrial reactive oxygen species, tissue reactive oxygen species levels, and upregulates antioxidants and their promoters. When the CK capacity of CKmito-overexpressing mice is limited by creatine substrate depletion, the protection against pathologic remodeling is lost, suggesting the ADP regenerating capacity of the CKmito reaction rather than CK protein per se is critical in limiting adverse HF remodeling.
CONCLUSIONS: In the failing human heart, pathologic hypertrophy and adverse remodeling are closely related to deficits in ATP levels and in the CK energy reserve reaction. CKmito, sitting at the intersection of cardiac energetics and redox balance, plays a crucial role in attenuating pathologic remodeling in HF.
REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00181259.

Keywords:  antioxidants; creatine; dilatation; heart failure; myofibrils

DOI:  https://doi.org/10.1161/CIRCRESAHA.121.319648
Nat Commun. 2022 Feb 03. 13(1): 653

TAZ links exercise to mitochondrial biogenesis via mitochondrial transcription factor A.

Jun-Ha Hwang, Kyung Min Kim, Ho Taek Oh, Gi Don Yoo, Mi Gyeong Jeong, Hyun Lee, Joori Park, Kwon Jeong, Yoon Ki Kim, Young-Gyu Ko, Eun Sook Hwang, Jeong-Ho Hong.

Mitochondria are energy-generating organelles and mitochondrial biogenesis is stimulated to meet energy requirements in response to extracellular stimuli, including exercise. However, the mechanisms underlying mitochondrial biogenesis remain unknown. Here, we demonstrate that transcriptional coactivator with PDZ-binding motif (TAZ) stimulates mitochondrial biogenesis in skeletal muscle. In muscle-specific TAZ-knockout (mKO) mice, mitochondrial biogenesis, respiratory metabolism, and exercise ability were decreased compared to wild-type mice. Mechanistically, TAZ stimulates the translation of mitochondrial transcription factor A via Ras homolog enriched in brain (Rheb)/Rheb like 1 (Rhebl1)-mTOR axis. TAZ stimulates Rhebl1 expression via TEA domain family transcription factor. Rhebl1 introduction by adeno-associated virus or mTOR activation recovered mitochondrial biogenesis in mKO muscle. Physiologically, mKO mice did not stimulate exercise-induced mitochondrial biogenesis. Collectively, our results suggested that TAZ is a novel stimulator for mitochondrial biogenesis and exercise-induced muscle adaptation.

DOI: https://doi.org/10.1038/s41467-022-28247-2
Transl Cancer Res. 2021 Feb;10(2): 817-826

The effects of hypoxia on mitochondrial function and metabolism in gastric cancer cells.

Jun Jiang, Yuan Jiang, Yao-Gang Zhang, Tao Zhang, Jian-Hua Li, Deng-Liang Huang, Jing Hou, Mei-Yuan Tian, Li Sun, Xiao-Ming Su, Yun Dong, Yan-Yan Ma.

   Background: A number of studies have found that metabolic disorders are the characteristic manifestations of tumor cells. However, the effects of hypoxic environment on mitochondrial function and glucose metabolism of tumor cells were still unclear. The study wanted to explore the regulatory mechanism of hypoxic environment on mitochondrial function and metabolism in gastric cancer cells.
Methods: The animal model of gastric cancer and MKN45 were treated in a hypoxic environment. Mitochondrial membrane potential and reactive oxygen species (ROS) levels were analyzed by flow cytometry, qPCR was used to detect the expression levels of glycose metabolism key enzymes, damage repair genes and mitochondrial DNA (mtDNA) copy numbers in gastric cancer.
Results: Compared with 2,000 m normal gastric cancer tissue, the decreased of mitochondrial membrane potential and the production of ROS reduced, the expressions of glucose metabolism genes [the M1 isoform of Hexokinase (HK1), pyruvate kinase (PKM), Succinate dehydrogenase (SDHA), Glucose-6-phosphate dehydrogenase (G6PD)], homologous recombination repair gene (RAD51) and repair DNA double-stranded broken gene (ASTCT2) increased, and aerobic respiration reduced in gastric cancer cells. In the hypoxic environment, the decreased of mitochondrial membrane potential reduced, the production of ROS and mtDNA copies increased, HK1 expression increased, the expressions of SDHA, G6PD, RAD51 and ASCT-2 decreased, and the aerobic respiration decreased.
Conclusions: Hypoxia plays an important role in maintaining mitochondrial functions in gastric cancer cells by promoting glycolysis and inhibiting mitochondrial aerobic respiration capacity.

Keywords:  Gastric cancer; aerobic respiration; hypoxia; mitochondrial function

DOI:  https://doi.org/10.21037/tcr-20-2598
Cell Chem Biol. 2022 Jan 27. pii: S2451-9456(22)00050-2. [Epub ahead of print]

Selective vulnerabilities in the proteostasis network of castration-resistant prostate cancer.

Arielle Shkedi, Isabelle R Taylor, Frank Echtenkamp, Poornima Ramkumar, Mohamed Alshalalfa, Génesis M Rivera-Márquez, Michael A Moses, Hao Shao, Robert Jeffrey Karnes, Len Neckers, Felix Feng, Martin Kampmann, Jason E Gestwicki.

  Castration-resistant prostate cancer (CRPC) is associated with an increased reliance on heat shock protein 70 (HSP70), but it is not clear what other protein homeostasis (proteostasis) factors might be involved. To address this question, we performed functional and synthetic lethal screens in four prostate cancer cell lines. These screens confirmed key roles for HSP70, HSP90, and their co-chaperones, but also suggested that the mitochondrial chaperone, HSP60/HSPD1, is selectively required in CRPC cell lines. Knockdown of HSP60 does not impact the stability of androgen receptor (AR) or its variants; rather, it is associated with loss of mitochondrial spare respiratory capacity, partly owing to increased proton leakage. Finally, transcriptional data revealed a correlation between HSP60 levels and poor survival of prostate cancer patients. These findings suggest that re-wiring of the proteostasis network is associated with CRPC, creating selective vulnerabilities that might be targeted to treat the disease.

Keywords:  chaperones; functional genomics; heat shock proteins; mitochondria; prostate cancer; proteostasis; shRNA

DOI:  https://doi.org/10.1016/j.chembiol.2022.01.008
Bioeng Transl Med. 2022 Jan;7(1): e10250

In-cytoplasm mitochondrial transplantation for mesenchymal stem cells engineering and tissue regeneration.

Xudong Yao, Yuanzhu Ma, Wenyan Zhou, Youguo Liao, Zongsheng Jiang, Junxin Lin, Qiulin He, Hongwei Wu, Wei Wei, Xiaozhao Wang, Mikael Björklund, Hongwei Ouyang.

  Stem cell therapies are unsatisfactory due to poor cell survival and engraftment. Stem cell used for therapy must be properly "tuned" for a harsh in vivo environment. Herein, we report that transfer of exogenous mitochondria (mito) to adipose-derived mesenchymal stem cells (ADSCs) can effectively boost their energy levels, enabling efficient cell engraftment. Importantly, the entire process of exogeneous mitochondrial endocytosis is captured by high-content live-cell imaging. Mitochondrial transfer leads to acutely enhanced bioenergetics, with nearly 17% of higher adenosine 5'-triphosphate (ATP) levels in ADSCs treated with high mitochondrial dosage and further results in altered secretome profiles of ADSCs. Mitochondrial transfer also induced the expression of 334 mRNAs in ADSCs, which are mainly linked to signaling pathways associated with DNA replication and cell division. We hypothesize that increase in ATP and cyclin-dependent kinase 1 and 2 expression might be responsible for promoting enhanced proliferation, migration, and differentiation of ADSCs in vitro. More importantly, mito-transferred ADSCs display prolonged cell survival, engraftment and horizontal transfer of exogenous mitochondria to surrounding cells in a full-thickness skin defect rat model with improved skin repair compared with nontreated ADSCs. These results demonstrate that intracellular mitochondrial transplantation is a promising strategy to engineer stem cells for tissue regeneration.

Keywords:  bioenergetics; mesenchymal stem cells; mitochondrial transfer; tissue regeneration

DOI:  https://doi.org/10.1002/btm2.10250
Biol Chem. 2022 Jan 31.

Yme2, a putative RNA recognition motif and AAA+ domain containing protein, genetically interacts with the mitochondrial protein export machinery.

Nupur Sharma, Christof Osman.

  The mitochondrial respiratory chain is composed of nuclear as well as mitochondrial-encoded subunits. A variety of factors mediate co-translational integration of mtDNA-encoded proteins into the inner membrane. In Saccharomyces cerevisiae, Mdm38 and Mba1 are ribosome acceptors that recruit the mitochondrial ribosome to the inner membrane, where the insertase Oxa1, facilitates membrane integration of client proteins. The protein Yme2 has previously been shown to be localized in the inner mitochondrial membrane and has been implicated in mitochondrial protein biogenesis, but its mode of action remains unclear. Here, we show that multiple copies of Yme2 assemble into a high molecular weight complex. Using a combination of bioinformatics and mutational analyses, we find that Yme2 possesses an RNA recognition motif (RRM), which faces the mitochondrial matrix and a AAA+ domain that is located in the intermembrane space. We further show that YME2 genetically interacts with MDM38, MBA1 and OXA1, which links the function of Yme2 to the mitochondrial protein biogenesis machinery.

Keywords:  MBA1; MDM38; OXA1; RRM; Walker motifs; mitoribosome

DOI:  https://doi.org/10.1515/hsz-2021-0398
Leukemia. 2022 Feb 02.

CDK19 regulates the proliferation of hematopoietic stem cells and acute myeloid leukemia cells by suppressing p53-mediated transcription of p21.

Zihao Zhang, Yukai Lu, Yan Qi, Yang Xu, Song Wang, Fang Chen, Mingqiang Shen, Mo Chen, Naicheng Chen, Lijing Yang, Shilei Chen, Fengchao Wang, Yongping Su, Mengjia Hu, Junping Wang.

The cell cycle progression of hematopoietic stem cells (HSCs) and acute myeloid leukemia (AML) cells is precisely controlled by multiple regulatory factors. However, the underlying mechanisms are not fully understood. Here, we find that cyclin-dependent kinase 19 (CDK19), not its paralogue CDK8, is relatively enriched in mouse HSCs, and its expression is more significantly increased than CDK8 after proliferative stresses. Furthermore, SenexinB (a CDK8/19 inhibitor) treatment impairs the proliferation and self-renewal ability of HSCs. Moreover, overexpression of CDK19 promotes HSC function better than CDK8 overexpression. Using CDK19 knockout mice, we observe that CDK19-/- HSCs exhibit similar phenotypes to those of cells treated with SenexinB. Interestingly, the p53 signaling pathway is significantly activated in HSCs lacking CDK19 expression. Further investigations show that CDK19 can interact with p53 to inhibit p53-mediated transcription of p21 in HSCs and treatment with a specific p53 inhibitor (PFTβ) partially rescues the defects of CDK19-null HSCs. Importantly, SenexinB treatment markedly inhibits the proliferation of AML cells. Collectively, our findings indicate that CDK19 is involved in regulating HSC and AML cell proliferation via the p53-p21 pathway, revealing a new mechanism underlying cell cycle regulation in normal and malignant hematopoietic cells.

DOI: https://doi.org/10.1038/s41375-022-01512-5
Proc Natl Acad Sci U S A. 2022 Feb 08. pii: e2107599119. [Epub ahead of print]119(6):

Loss of TET reprograms Wnt signaling through impaired demethylation to promote lung cancer development.

Qin Xu, Chao Wang, Jia-Xin Zhou, Zhi-Mei Xu, Juan Gao, Pengfei Sui, Colum P Walsh, Hongbin Ji, Guo-Liang Xu.

  Oncogenic imbalance of DNA methylation is well recognized in cancer development. The ten-eleven translocation (TET) family of dioxygenases, which facilitates DNA demethylation, is frequently dysregulated in cancers. How such dysregulation contributes to tumorigenesis remains poorly understood, especially in solid tumors which present infrequent mutational incidence of TET genes. Here, we identify loss-of-function mutations of TET in 7.4% of human lung adenocarcinoma (LUAD), which frequently co-occur with oncogenic KRAS mutations, and this co-occurrence is predictive of poor survival in LUAD patients. Using an autochthonous mouse model of KrasG12D -driven LUAD, we show that individual or combinational loss of Tet genes markedly promotes tumor development. In this Kras-mutant and Tet-deficient model, the premalignant lung epithelium undergoes neoplastic reprogramming of DNA methylation and transcription, with a particular impact on Wnt signaling. Among the Wnt-associated components that undergo reprogramming, multiple canonical Wnt antagonizing genes present impaired expression arising from elevated DNA methylation, triggering aberrant activation of Wnt signaling. These impairments can be largely reversed upon the restoration of TET activity. Correspondingly, genetic depletion of β-catenin, the transcriptional effector of Wnt signaling, substantially reverts the malignant progression of Tet-deficient LUAD. These findings reveal TET enzymes as critical epigenetic barriers against lung tumorigenesis and highlight the therapeutic vulnerability of TET-mutant lung cancer through targeting Wnt signaling.

Keywords:  DNA dioxygenases; Wnt antagonizing genes; epigenetic barriers; lung adenocarcinoma; mouse models

DOI:  https://doi.org/10.1073/pnas.2107599119
Transl Cancer Res. 2020 May;9(5): 3610-3622

Elevated expression of mitochondrial transcription elongation factor (TEFM) predicts poor prognosis in low grade glioma-an analysis of the Cancer Genome Atlas (TCGA) dataset.

Sufen Li, Weisi Wang, Jiaji Zi, Meitao Sun, Wen Mei, Na Yang, Ruopeng Zhang, Min Yu, Wei Xiong.

   Background: Mitochondrial transcription elongation factor (TEFM) is a key molecule for mitochondrial DNA (mtDNA) replication-transcription switch. TEFM regulates both transcription elongation and RNA processing in mitochondria. However, the expression level and prognostic value of TEFM in low grade glioma (LGG) remain unclear. Therefore, in this study, we aimed to evaluate the clinical significance and the prognostic value of TEFM in LGG based on publicly available data.
Methods: The relative mRNA expression level of TEFM in non-tumor brain tissues and LGG tissues were retrieved from Gene Expression Profiling Interactive Analysis (GEPIA). The RNA-Seq expression of TEFM and clinical information in LGG patients were collected from the updated the Cancer Genome Atlas (TCGA) database by using R3.6.1 software. Next, the relationship between the mRNA expression of TEFM and clinicopathological characteristics were analyzed. Kaplan-Meier survival curves of overall survival (OS) and disease-free survival (DFS) were implemented for the relationship between the mRNA expression of TEFM and the prognosis of LGG patients. A Cox regression model was performed for the multivariate analysis of the factors affected the prognosis of LGG patients. GEPIA online tool was used to analyze the correlation between TEFM gene expression level and other related mitochondrial regulatory genes in LGG. Finally, The Gene Set Enrichment Analysis (GSEA) was performed to identify cell processes and molecular signaling cascades affected by TEFM.
Results: GEPIA analysis showed that the mRNA expression levels of TEFM in LGG were significantly higher than that of non-tumor tissue. Moreover, the mRNA expression of TEFM is significantly correlated with age, World Health Organization (WHO) grade, pathological types, headache history and supratentorial location (P<0.05). Kaplan-Meier analysis showed that a high expression level of TEFM mRNA indicated a poor prognosis in OS rate (log-rank, P<0.01). Multivariate Cox regression analysis showed that age, WHO grade, pathological types and supratentorial location were the independent prognostic factors of LGG patients. The mRNA expression levels of TEFM gene were positively correlated with the TFAM, TFB1M, TFB2M, MTERF1-F4 and NRF1 gene (P<0.01, R>0), but negatively correlated with the POLRMT gene (P<0.01, R=-0.18) in LGG. The GSEA revealed that genes associated with the cell cycle, RNA degradation, spliceosome, and ubiquitin mediated proteolysis signaling pathway were remarkably enriched in higher-TEFM versus lower-TEFM tumors.
Conclusions: Our findings disclosed that the expression of TEFM mRNA was significantly upregulated in human LGG tissues compared to non-tumor brain tissues. More importantly, the elevated expression of TEFM mRNA may potentially predict poor OS in LGG patients.

Keywords:  The Cancer Genome Atlas dataset (TCGA dataset); low grade glioma (LGG); mitochondrial transcription elongation factor (TEFM); prognosis

DOI:  https://doi.org/10.21037/tcr.2020.04.16
Nat Cancer. 2020 Jul;1(7): 735-747

Aldolase B suppresses hepatocellular carcinogenesis by inhibiting G6PD and pentose phosphate pathways.

Min Li, Xuxiao He, Weixing Guo, Hongming Yu, Shicheng Zhang, Ningning Wang, Guijun Liu, Rina Sa, Xia Shen, Yabo Jiang, Yufu Tang, Yujuan Zhuo, Chunzhao Yin, Qiaochu Tu, Nan Li, Xiaoqun Nie, Yu Li, Zhimin Hu, Hanwen Zhu, Jianping Ding, Zi Li, Te Liu, Fan Zhang, He Zhou, Shengxian Li, Jiang Yue, Zheng Yan, Shuqun Cheng, Yongzhen Tao, Huiyong Yin.

Metabolic reprogramming is a core hallmark of cancer but it remains poorly defined in hepatocellular carcinogenesis (HCC). Here we show that hepatic aldolase B (Aldob) suppresses HCC by directly binding and inhibiting the rate-limiting enzyme in the pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G6PD). A stage-dependent decrease of Aldob and increase of G6PD in human tumors are correlated with poor prognosis for patients with HCC. Global or liver-specific Aldob knockout promotes tumorigenesis in mice through enhancing G6PD activity and pentose phosphate pathway metabolism, whereas pharmacological inhibition or genetic knockdown of G6PD suppresses HCC. Consistently, restoration of Aldob in Aldob knockout mice attenuates tumorigenesis. We further demonstrate that Aldob potentiates p53-mediated inhibition of G6PD in an Aldob-G6PD-p53 complex. This scaffolding effect is independent of Aldob enzymatic activity. Together, our study reveals a new mode of metabolic reprogramming in HCC due to the loss of Aldob, suggesting a potential therapeutic strategy for HCC treatment.

DOI: https://doi.org/10.1038/s43018-020-0086-7
Nat Cancer. 2021 Nov;2(11): 1152-1169

NR2F2 controls malignant squamous cell carcinoma state by promoting stemness and invasion and repressing differentiation.

Federico Mauri, Corentin Schepkens, Gaëlle Lapouge, Benjamin Drogat, Yura Song, Ievgenia Pastushenko, Sandrine Rorive, Jeremy Blondeau, Sophie Golstein, Yacine Bareche, Marie Miglianico, Erwin Nkusi, Milena Rozzi, Virginie Moers, Audrey Brisebarre, Maylis Raphaël, Christine Dubois, Justine Allard, Benoit Durdu, Floriane Ribeiro, Christos Sotiriou, Isabelle Salmon, Jalal Vakili, Cédric Blanpain.

The nongenetic mechanisms required to sustain malignant tumor state are poorly understood. During the transition from benign tumors to malignant carcinoma, tumor cells need to repress differentiation and acquire invasive features. Using transcriptional profiling of cancer stem cells from benign tumors and malignant skin squamous cell carcinoma (SCC), we identified the nuclear receptor NR2F2 as uniquely expressed in malignant SCC. Using genetic gain of function and loss of function in vivo, we show that NR2F2 is essential for promoting the malignant tumor state by controlling tumor stemness and maintenance in mouse and human SCC. We demonstrate that NR2F2 promotes tumor cell proliferation, epithelial-mesenchymal transition and invasive features, while repressing tumor differentiation and immune cell infiltration by regulating a common transcriptional program in mouse and human SCCs. Altogether, we identify NR2F2 as a key regulator of malignant cancer stem cell functions that promotes tumor renewal and restricts differentiation to sustain a malignant tumor state.

DOI: https://doi.org/10.1038/s43018-021-00287-5
J Immunother Cancer. 2022 Feb;pii: e003958. [Epub ahead of print]10(2):

Chemical augmentation of mitochondrial electron transport chains tunes T cell activation threshold in tumors.

Yosuke Dotsu, Daisuk Muraoka, Naohisa Ogo, Yudai Sonoda, Kiyoshi Yasui, Hiroyuki Yamaguchi, Hideo Yagita, Hiroshi Mukae, Akira Asai, Hiroaki Ikeda.

   BACKGROUND: Cancer immunotherapy shows insufficient efficacy for low immunogenic tumors. Furthermore, tumors often downregulate antigen and major histocompatibility complex expression to escape recognition by T cells, resulting in insufficient T cell receptor (TCR) stimulation in the tumor microenvironment. Thus, augmenting TCR-mediated recognition of tumor antigens is a useful strategy to improve the efficacy of cancer immunotherapy.
METHODS: We screened 310 small molecules from our library and identified PQDN, a small molecule that activates CD8 T cells after TCR engagement, even when antigen stimulation is too weak for their activation. We used inhibitors of mitochondrial functions and Seahorse Flux Analyzer to investigate the mechanism underlying the effect of PQDN on T cells. Effect of PQDN on tumor-infiltrating CD8 T cells was examined using flow cytometry and TCR repertoire analysis.
RESULTS: PQDN increased mitochondrial reciprocal capacity through enhancement of electron transport chains (ETCs) and facilitated glycolysis via mTOR/AKT signaling, resulting in augmented CD8 T cell activation, even when antigen stimulation is extremely weak. Intratumoral administration of this compound into tumor-bearing mice tunes inactivated T cell with tumor antigen recognition potent and expanded functional T cell receptor diversity of tumor-infiltrating T cells, augmenting antitumor immune responses and retarding tumor growth. Furthermore, PQDN has a synergistic potent with T cell dependent immunotherapy, such as checkpoint inhibitory therapy or adoptive cell therapy, even in a low immunogenic tumor. We also demonstrated that this compound enhances the activation of human CD8 T cells.
CONCLUSIONS: These data suggest that tuning the T cell activation threshold by chemical activation of mitochondrial ETC is a new strategy for improving therapeutic efficacy through the activation of low-avidity tumor-specific T cells.

Keywords:  CD8-positive T-lymphocytes; lymphocytes; metabolic networks and pathways; tumor-infiltrating

DOI:  https://doi.org/10.1136/jitc-2021-003958
Physiol Res. 2021 Dec 31. 70(S3): S369-S379

Mitochondrial respiration of human platelets in young adult and advanced age - Seahorse or O2k?

J Jedlička, R Kunc, J Kuncová.

The objective of the present study was to evaluate platelet mitochondrial oxygen consumption using high-resolution respirometry (HRR) and metabolic flux analysis (MFA) and to verify the effect of advanced age on these parameters. HRR was used to analyze permeabilized and intact platelets, MFA to measure oxygen consumption rates (OCR), extracellular acidification rates (ECAR) and ATP production rate in intact fixed platelets. Two groups of healthy volunteers were included in the study: YOUNG (20-42 years, n=44) and older adults (OLD; 70-89 years; n=15). Compared to YOUNG donors, platelets from group OLD participants displayed significantly lower values of oxygen consumption in the Complex II-linked phosphorylating and uncoupled states and the Complex IV activity in HRR protocols for permeabilized cells and significantly lower resting and uncoupled respirations in intact cells when analyzed by both methods. In addition, mitochondrial ATP production rate was also significantly lower in platelets isolated from older adults. Variables measured by both methods from the same bloods correlated significantly, nevertheless those acquired by MFA were higher than those measured using HRR. In conclusion, the study verifies compromised mitochondrial respiration and oxidative ATP production in the platelets of aged persons and documents good compatibility of the two most widely used methods for determining the global performance of the electron-transporting system, i.e. HRR and MFA.
Sci Rep. 2022 Feb 02. 12(1): 1801

Comparison of mitochondrial DNA sequences from whole blood and lymphoblastoid cell lines.

Chunyu Liu, Jessica L Fetterman, Xianbang Sun, Kaiyu Yan, Poching Liu, Yan Luo, Jun Ding, Jun Zhu, Daniel Levy.

Lymphoblastoid cell lines (LCLs) provide an unlimited source of genomic DNA for genetic studies. Here, we compared mtDNA sequence variants, heteroplasmic or homplasmic, between LCL (sequenced by mitoRCA-seq method) and whole blood samples (sequenced through whole genome sequencing approach) of the same 130 participants in the Framingham Heart Study. We applied harmonization of sequence coverages and consistent quality control to mtDNA sequences. We identified 866 variation sites in the 130 LCL samples and 666 sites in the 130 blood samples. More than 94% of the identified homoplasmies were present in both LCL and blood samples while more than 70% of heteroplasmic sites were uniquely present either in LCL or in blood samples. The LCL and whole blood samples carried a similar number of homoplasmic variants (p = 0.45) per sample while the LCL carried a greater number of heteroplasmic variants than whole blood per sample (p < 2.2e-16). Furthermore, the LCL samples tended to accumulate low level heteroplasmies (heteroplasmy level in 3-25%) than their paired blood samples (p = 0.001). These results suggest that cautions should be taken in the interpretation and comparison of findings when different tissues/cell types or different sequencing technologies are applied to obtain mtDNA sequences.

DOI: https://doi.org/10.1038/s41598-022-05814-7
Toxicol In Vitro. 2022 Feb 01. pii: S0887-2333(22)00022-4. [Epub ahead of print] 105325

Albumin binds to uncoupler CCCP to diminish depolarization of mitochondria.

Ganjoo Mahalaxmi, Sivasailam Ashok, Gangadharan Arun, Gopala Srinivas.

  Mitochondria are at the core of cellular energy metabolism and are also involved in the oxidative stress response and programmed cell death pathways. Mitochondrial dysfunction is found to be associated with many disease conditions like metabolic syndrome, neurodegenerative disorders, coronary artery diseases, cancer, etc. This has generated considerable interest in the scientific community over the assessment of mitochondrial function and mitochondrial damage. One of the most common methodologies in these studies is by analysing the mitochondrial activity in the presence of mitochondrial substrates, inhibitors and uncouplers. Apart from the specific effects of these molecules on mitochondria, their interactions with the components of the experimental system could interfere with the results derived. Therefore, the role some specific experimental conditions would have on the outcome should be carefully elucidated. Fetal Bovine Serum or Bovine Serum Albumin (BSA); routinely used in in vitro experiments for their growth promoting and surfactant properties; can have profound impact on the pharmacokinetics of chemical compounds as albumin residue can bind to and affect their bioavailability. In the present study, we demonstrate that Carbonyl cyanide 3-chlorophenylhydrazone (CCCP) induced mitochondrial depolarization is hindered in the presence of albumin due to the molecular interaction between CCCP and albumin.

Keywords:  Albumin; BSA; CCCP; Mitochondrial depolarization; Serum

DOI:  https://doi.org/10.1016/j.tiv.2022.105325
FEBS Lett. 2022 Feb 04.

Diet-derived ergothioneine induces necroptosis in colorectal cancer cells by activating the SIRT3/MLKL pathway.

Nunzia D'Onofrio, Elisa Martino, Anna Balestrieri, Luigi Mele, Domenico Cautela, Domenico Castaldo, Maria Luisa Balestrieri.

  Ergothioneine (Egt) is a dietary amino acid which acts as an antioxidant to protect against aging-related diseases. We investigated the anticancer properties of Egt in colorectal cancer cells (CRC). Egt treatment exerted cytotoxicity in a dose-dependent manner, induced reactive oxygen species accumulation, loss of mitochondrial membrane potential, and upregulation of the histone deacetylase SIRT3. Immunoblotting analysis indicated that the cell death occurred via necroptosis through activation of the RIP1/RIP3/MLKL pathway. An immunoprecipitation assay unveiled that the interaction between the terminal effector in necroptotic signaling MLKL and SIRT3 increased during the Egt treatment. SIRT3 gene silencing blocked the upregulation of MLKL and abolished the ability of Egt to induce necroptosis. The SIRT3-MLKL interaction may mediate the necroptotic effects of Egt in CRC, suggesting the potential of this dietary amino-thione in the prevention of CRC.

Keywords:  Ergothioneine; RIP1/RIP3/MLKL; SIRT3; colon cancer; necroptosis

DOI:  https://doi.org/10.1002/1873-3468.14310
Nat Cancer. 2021 Dec;2(12): 1338-1356

APOBEC3A drives deaminase domain-independent chromosomal instability to promote pancreatic cancer metastasis.

Sonja M Wörmann, Amy Zhang, Fredrik I Thege, Robert W Cowan, Dhwani N Rupani, Runsheng Wang, Sara L Manning, Chris Gates, Weisheng Wu, Rena Levin-Klein, Kimal I Rajapakshe, Meifang Yu, Asha S Multani, Ya'an Kang, Cullen M Taniguchi, Katharina Schlacher, Melena D Bellin, Matthew H G Katz, Michael P Kim, Jason B Fleming, Steven Gallinger, Ravikanth Maddipati, Reuben S Harris, Faiyaz Notta, Susan R Ross, Anirban Maitra, Andrew D Rhim.

Despite efforts in understanding its underlying mechanisms, the etiology of chromosomal instability (CIN) remains unclear for many tumor types. Here, we identify CIN initiation as a previously undescribed function for APOBEC3A (A3A), a cytidine deaminase upregulated across cancer types. Using genetic mouse models of pancreatic ductal adenocarcinoma (PDA) and genomics analyses in human tumor cells we show that A3A-induced CIN leads to aggressive tumors characterized by enhanced early dissemination and metastasis in a STING-dependent manner and independently of the canonical deaminase functions of A3A. We show that A3A upregulation recapitulates numerous copy number alterations commonly observed in patients with PDA, including co-deletions in DNA repair pathway genes, which in turn render these tumors susceptible to poly (ADP-ribose) polymerase inhibition. Overall, our results demonstrate that A3A plays an unexpected role in PDA as a specific driver of CIN, with significant effects on disease progression and treatment.

DOI: https://doi.org/10.1038/s43018-021-00268-8
Nat Commun. 2022 Feb 01. 13(1): 607

The mouse metallomic landscape of aging and metabolism.

Jean-David Morel, Lucie Sauzéat, Ludger J E Goeminne, Pooja Jha, Evan Williams, Riekelt H Houtkooper, Ruedi Aebersold, Johan Auwerx, Vincent Balter.

Organic elements make up 99% of an organism but without the remaining inorganic bioessential elements, termed the metallome, no life could be possible. The metallome is involved in all aspects of life, including charge balance and electrolytic activity, structure and conformation, signaling, acid-base buffering, electron and chemical group transfer, redox catalysis energy storage and biomineralization. Here, we report the evolution with age of the metallome and copper and zinc isotope compositions in five mouse organs. The aging metallome shows a conserved and reproducible fingerprint. By analyzing the metallome in tandem with the phenome, metabolome and proteome, we show networks of interactions that are organ-specific, age-dependent, isotopically-typified and that are associated with a wealth of clinical and molecular traits. We report that the copper isotope composition in liver is age-dependent, extending the existence of aging isotopic clocks beyond bulk organic elements. Furthermore, iron concentration and copper isotope composition relate to predictors of metabolic health, such as body fat percentage and maximum running capacity at the physiological level, and adipogenesis and OXPHOS at the biochemical level. Our results shed light on the metallome as an overlooked omic layer and open perspectives for potentially modulating cellular processes using careful and selective metallome manipulation.

DOI: https://doi.org/10.1038/s41467-022-28060-x
Proc Natl Acad Sci U S A. 2022 Feb 08. pii: e2120617119. [Epub ahead of print]119(6):

Loss of glucose 6-phosphate dehydrogenase function increases oxidative stress and glutaminolysis in metastasizing melanoma cells.

Arin B Aurora, Vishal Khivansara, Ashley Leach, Jennifer G Gill, Misty Martin-Sandoval, Chendong Yang, Stacy Y Kasitinon, Divya Bezwada, Alpaslan Tasdogan, Wen Gu, Thomas P Mathews, Zhiyu Zhao, Ralph J DeBerardinis, Sean J Morrison.

  The pentose phosphate pathway is a major source of NADPH for oxidative stress resistance in cancer cells but there is limited insight into its role in metastasis, when some cancer cells experience high levels of oxidative stress. To address this, we mutated the substrate binding site of glucose 6-phosphate dehydrogenase (G6PD), which catalyzes the first step of the pentose phosphate pathway, in patient-derived melanomas. G6PD mutant melanomas had significantly decreased G6PD enzymatic activity and depletion of intermediates in the oxidative pentose phosphate pathway. Reduced G6PD function had little effect on the formation of primary subcutaneous tumors, but when these tumors spontaneously metastasized, the frequency of circulating melanoma cells in the blood and metastatic disease burden were significantly reduced. G6PD mutant melanomas exhibited increased levels of reactive oxygen species, decreased NADPH levels, and depleted glutathione as compared to control melanomas. G6PD mutant melanomas compensated for this increase in oxidative stress by increasing malic enzyme activity and glutamine consumption. This generated a new metabolic vulnerability as G6PD mutant melanomas were more dependent upon glutaminase than control melanomas, both for oxidative stress management and anaplerosis. The oxidative pentose phosphate pathway, malic enzyme, and glutaminolysis thus confer layered protection against oxidative stress during metastasis.

Keywords:  glutaminolysis; melanoma; metastasis; oxidative stress; pentose phosphate pathway

DOI:  https://doi.org/10.1073/pnas.2120617119
Alzheimers Dement. 2021 Dec;17 Suppl 3 e051283

Impaired mitochondrial ATP production, reduced mitochondrial spare respiratory capacity, and increased oxidative stress in PBMCs are associated with aging in adult EGAT population.

Sirawit Sriwichaiin, Nattayaporn Apaijai, Arintaya Phrommintikul, Thidarat Jaiwongkam, Sasiwan Kerdphoo, Sirintorn Chansirikarnjana, Nisakron Thongmung, Usanee Mahantassanapong, Prin Vathesatogkit, Chrigriya Kitiyakara, Piyamitr Sritara, Nipon Chattipakorn, Siriporn C Chattipakorn.

BACKGROUND: Aging is associated with the degeneration of several tissues, and that degeneration has an impact on the structure and function of organs. Aging is the most potential risk factor for chronic diseases, particularly dementia. Mitochondrial function is one of the important processes to maintain the metabolism in cells and organs. Mitochondrial function in peripheral blood mononuclear cells (PBMCs) can be a biomarker for several chronic disease. However, the association between aging and mitochondrial function from PBMCs of healthy adult population has not been elusive. Thus, the present study aims to explore the association between aging and mitochondrial function in human PBMCs.
METHOD: The participants were recruited from Electricity Generating Authority of Thailand (EGAT). The demographic data were collected. The basic laboratory parameters were obtained by venipuncture. The PBMCs were also isolated from the venous blood of the participant and then underwent a mitochondrial function test by Seahorse assay. The mitochondrial oxidative stress and mass were assessed by MitoSox and MitoTracker fluorescent dyes and were quantified by flow cytometry. The data of 1,753 participants remained in the final analysis. The associations of age and mitochondrial respiratory parameters were assessed by linear regression analysis. The covariates including underlying diseases of participants and the basic laboratory parameters obtained in this study were used to evaluate the independent associations of age on mitochondrial functions.
RESULT: The general characteristics of the participants in this study were shown in Table 1. The increased age associated with the reduction in mitochondrial ATP production (beta coefficient [95% confident interval] = -0.59 [-0.76,-0.43]) and mitochondrial spare respiratory capacity (-3.30 [-3.65,-2.95]) in PBMCs. Furthermore, the higher age is associated with the higher mitochondrial oxidative stress/mass ratio (0.0045 [0.0040,0.0050]). After adjusted with underlying diseases or basic laboratory parameters, these associations were still in the same direction as univariate analysis.
CONCLUSION: Aging was associated with mitochondrial dysfunction in PBMCs as indicated by the reduction in mitochondrial ATP production and mitochondrial spare respiratory capacity and elevation of mitochondrial oxidative stress/mass ratio. Further investigation on these findings might be useful to develop novel disease interventions or biomarkers for chronic diseases, particularly dementia.

DOI: https://doi.org/10.1002/alz.051283
Elife. 2022 Feb 02. pii: e69096. [Epub ahead of print]11

Cooperation among c-subunits of FoF1-ATP synthase in rotation-coupled proton translocation.

Noriyo Mitome, Shintaroh Kubo, Sumie Ohta, Hikaru Takashima, Yuto Shigefuji, Toru Niina, Shoji Takada.

  In FoF1-ATP synthase, proton translocation through Fo drives rotation of the c-subunit oligomeric ring relative to the a-subunit. Recent studies suggest that in each step of the rotation, key glutamic acid residues in different c-subunits contribute to proton release to and proton uptake from the a-subunit. However, no studies have demonstrated cooperativity among c-subunits toward FoF1-ATP synthase activity. Here, we addressed this using Bacillus PS3 ATP synthase harboring a c-ring with various combinations of wild-type and cE56D, enabled by genetically fused single-chain c-ring. ATP synthesis and proton pump activities were decreased by a single cE56D mutation and further decreased by double cE56D mutations. Moreover, activity further decreased as the two mutation sites were separated, indicating cooperation among c-subunits. Similar results were obtained for proton transfer-coupled molecular simulations. The simulations revealed that prolonged proton uptake in mutated c-subunits is shared between two c-subunits, explaining the cooperation observed in biochemical assays.

Keywords:  E. coli; FoF1-ATP synthase; biochemistry; chemical biology; molecular simulations; proton uptake; single-chain c-ring

DOI:  https://doi.org/10.7554/eLife.69096
J Photochem Photobiol B. 2022 Jan 24. pii: S1011-1344(21)00255-4. [Epub ahead of print]228 112376

Photo-activation of mitochondrial ATP synthesis.

Igor Khmelinskii, Vladimir I Makarov.

  ATP production by mitochondria isolated from Saccharomyces cerevisiae cells was accelerated upon both direct and indirect mitochondrial photo-activation (MPA). The extent of direct MPA was dependent on the wavelength of excitation light. Direct MPA was created by light in cytochrome c spectral absorption bands (440, 520 and 550 nm), this light was absorbed producing electronically excited cytochrome c, and the excitation energy of the latter was used in the ATP production chain. The activity of cytochrome c was tested with 600 nm light, where cytochrome c does not absorb, and thus ATP production rate remained the same as in darkness. Note that ATP production rates were significantly larger under light at 550, 520 and 440 nm. Therefore, photo-activation of cytochrome c was the first step of MPA synthesis of ATP. Indirect MPA of ATP production also proceeded via electronically excited cytochrome c, by energy transfer from electronically excited Co/BN film to cytochrome c located in the inner mitochondrial membrane (IMM). Co/BN excitons were generated by photons absorbed by the Co/BN film, which was not in contact with the mitochondrial sample. Next, these excitons propagated along the Co/BN film to the part of the film that was in contact with the mitochondrial sample. There the exciton energy was transferred to cytochrome c located in the IMM, producing electronically excited cytochrome c. Thus, excited cytochrome c was generated in a way different from that of direct MPA. Next, the energy of excited cytochrome c was used in activated ATP synthesis, with virtually the same effect for 519 and 427 nm excitation. Thus, the first step of ATP synthesis in indirect MPA was the exciton energy transfer from Co/BN film to cytochrome c located in the IMM, producing an electronically excited cytochrome c molecule. A phenomenological mechanism of direct and indirect MPA was proposed, and the model parameters were obtained by fitting the model to the experimental data. However, more information is needed before the detailed mechanism of ATP synthesis activation by electronically excited cytochrome c could be understood. The present results support the earlier proposed hypothesis of indirect MPA of ATP production in vertebrate retina in daylight.

Keywords:  ATP; Direct photo-activation; Indirect photo-activation; Mitochondria; Yeast cell

DOI:  https://doi.org/10.1016/j.jphotobiol.2021.112376