bims-almceb 2022-03-13 papers

bims-almceb

Biomed News

on Acute Leukemia Metabolism and Cell Biology

Issue of 2022–03–13
fiveteen papers selected by
Camila Kehl Dias, Federal University of Rio Grande do Sul

Lipid metabolism of cancer stem cells.
mTOR inhibition downregulates glucose-6-phosphate dehydrogenase and induces ROS-dependent death in T-cell acute lymphoblastic leukemia cells.
Oscillations and Dynamic Symbiosis in Cellular Metabolism in Cancer.
Loss of IRF7 accelerates acute myeloid leukemia progression and induces VCAM1-VLA-4 mediated intracerebral invasion.
Metabolic tricks of cancer cells.
Role of Mitochondrial Stress Response in Cancer Progression.
Molecular Docking as a Therapeutic Approach for Targeting Cancer Stem Cell Metabolic Processes.
Mitochondrial respiration supports autophagy to provide stress resistance during quiescence.
Metabolomics analysis reveals Oct4 overexpression drives metabolic reprogramming and enhanced glycolysis and pentose phosphate pathway in lung adenocarcinoma cells.
CDK7/12/13 inhibition targets an oscillating leukemia stem cell network and synergizes with venetoclax in acute myeloid leukemia.
Targeting glutamine utilization to block metabolic adaptation of tumor cells under the stress of carboxyamidotriazole-induced nutrients unavailability.
Tumor Microenvironment in Acute Myeloid Leukemia: Adjusting Niches.
Extrusion of mitochondria: Garbage clearance or cell-cell communication signals?
Mito-FUNCAT-FACS reveals cellular heterogeneity in mitochondrial translation.
Targeting vulnerabilities of adult T-cell leukemia.

Oncol Lett. 2022 Apr;23(4): 119

Lipid metabolism of cancer stem cells.

Huihui Liu, Zhengyang Zhang, Lian Song, Jie Gao, Yanfang Liu.

  Cancer stem cells (CSCs), also termed cancer-initiating cells, are a special subset of cells with high self-replicating and self-renewing abilities that can differentiate into various cell types under certain conditions. A number of studies have demonstrated that CSCs have distinct metabolic properties. The reprogramming of energy metabolism enables CSCs to meet the needs of self-renewal and stemness maintenance. Increasing evidence supports the view that alterations in lipid metabolism, including an increase in fatty acid (FA) uptake, de novo lipogenesis, formation of lipid droplets and mitochondrial FA oxidation, are involved in CSC regulation. In the present review, the metabolic characteristics of CSCs, particularly in lipid metabolism, were summarized. In addition, the potential mechanisms of CSC lipid metabolism in treatment resistance were discussed. Given their significance in cancer biology, targeting CSC metabolism may serve an important role in future cancer treatment.

Keywords:  cancer stem cells; key modulators; lipid metabolism; metabolic reprogramming; resistant to therapy

DOI:  https://doi.org/10.3892/ol.2022.13239
Redox Biol. 2022 Feb 24. pii: S2213-2317(22)00040-4. [Epub ahead of print]51 102268

mTOR inhibition downregulates glucose-6-phosphate dehydrogenase and induces ROS-dependent death in T-cell acute lymphoblastic leukemia cells.

Micol Silic-Benussi, Evgenyia Sharova, Francesco Ciccarese, Ilaria Cavallari, Vittoria Raimondi, Loredana Urso, Alberto Corradin, Harel Kotler, Gloria Scattolin, Barbara Buldini, Samuela Francescato, Giuseppe Basso, Sonia A Minuzzo, Stefano Indraccolo, Donna M D'Agostino, Vincenzo Ciminale.

  mTOR activation is a hallmark of T-cell acute lymphoblastic leukemia (T-ALL) and is associated with resistance to glucocorticoid (GC)-based chemotherapy. We previously showed that altering redox homeostasis primes T-ALL cells to GC-induced apoptosis. Here we investigated the connection between the mTOR pathway and redox homeostasis using pharmacological inhibitors and gene silencing. In vitro studies performed on T-ALL cell lines and CG-resistant patient-derived T-ALL xenograft (PDX) cells showed that the mTOR inhibitor everolimus increased reactive oxygen species (ROS) levels, augmented lipid peroxidation, and activated the ROS-controlled transcription factor NRF2. These effects were accompanied by a decrease in the levels of NADPH and of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the pentose phosphate pathway (PPP), which is a major source of cytosolic NADPH needed for maintaining the cellular ROS-scavenging capacity. The mTOR inhibitor everolimus induced mitochondrial inner membrane depolarization and dose-dependent apoptosis of T-ALL cells, but did not kill normal T-cells. Importantly, the combination of everolimus and the GC dexamethasone had a synergistic effect on killing T-ALL cells. The effects of mTOR inhibition were blunted by ROS scavengers and phenocopied by siRNA-mediated G6PD silencing. In vivo studies of NOD/SCID mice inoculated with refractory T-ALL PDX demonstrated that everolimus overcame dexamethasone resistance in conditions of high tumor burden that mimicked the clinical setting of acute leukemia. These findings provide insight into the crosstalk between mTOR and ROS homeostasis in T-ALL cells and furnish mechanistic evidence to support the combination of glucocorticoids with mTOR inhibitors as a therapeutic avenue for treating refractory T-ALL.

Keywords:  G6PD; ROS; T-ALL; mTOR

DOI:  https://doi.org/10.1016/j.redox.2022.102268
Front Oncol. 2022 ;12 783908

Oscillations and Dynamic Symbiosis in Cellular Metabolism in Cancer.

Takashi Amemiya, Tomohiko Yamaguchi.

  The grade of malignancy differs among cancer cell types, yet it remains the burden of genetic studies to understand the reasons behind this observation. Metabolic studies of cancer, based on the Warburg effect or aerobic glycolysis, have also not provided any clarity. Instead, the significance of oxidative phosphorylation (OXPHOS) has been found to play critical roles in aggressive cancer cells. In this perspective, metabolic symbiosis is addressed as one of the ultimate causes of the grade of cancer malignancy. Metabolic symbiosis gives rise to metabolic heterogeneities which enable cancer cells to acquire greater opportunities for proliferation and metastasis in tumor microenvironments. This study introduces a real-time new imaging technique to visualize metabolic symbiosis between cancer-associated fibroblasts (CAFs) and cancer cells based on the metabolic oscillations in these cells. The causality of cellular oscillations in cancer cells and CAFs, connected through lactate transport, is a key point for the development of this novel technique.

Keywords:  cancer; heterogeneity; malignancy; metabolic oscillations; symbiosis

DOI:  https://doi.org/10.3389/fonc.2022.783908
Oncogene. 2022 Mar 07.

Loss of IRF7 accelerates acute myeloid leukemia progression and induces VCAM1-VLA-4 mediated intracerebral invasion.

Hao Wang, Dongyue Zhang, Xiaoxi Cui, Yibo Dai, Chenchen Wang, Wenli Feng, Xiaoqian Lv, Yifei Li, Lina Wang, Yongxin Ru, Yingchi Zhang, Qian Ren, Guoguang Zheng.

Interferon regulatory factor 7 (IRF7) is widely studied in inflammatory models. Its effects on malignant progression have been documented mainly from the perspective of the microenvironment. However, its role in leukemia has not been established. Here we used MLL-AF9-induced acute myeloid leukemia (AML) mouse models with IRF7 knockout or overexpression and xenograft mouse models to explore the intrinsic effects of IRF7 in AML. AML-IRF7-/- mice exhibited accelerated disease progression with intracerebral invasion of AML cells. AML-IRF7-/- cells showed increased proliferation and elevated leukemia stem cell (LSC) levels. Overexpression of IRF7 in AML cells decreased cell proliferation and LSC levels. Furthermore, overexpression of transforming growth-interacting factor 1 (TGIF1) rescued the enhanced proliferation and high LSC levels caused by IRF7 deficiency. Moreover, upregulation of vascular cell adhesion molecule 1 (VCAM1), which correlated with high LSC levels, was detected in AML-IRF7-/- cells. In addition, blocking VCAM1-very late antigen 4 (VLA-4) axis delayed disease progression and attenuated intracerebral invasion of AML cells. Therefore, our findings uncover the intrinsic effects of IRF7 in AML and provide a potential strategy to control central nervous system myeloid leukemia.

DOI: https://doi.org/10.1038/s41388-022-02233-w
Biochim Biophys Acta Rev Cancer. 2022 Mar 08. pii: S0304-419X(22)00030-0. [Epub ahead of print] 188705

Metabolic tricks of cancer cells.

Katerina Hönigova, Jiri Navratil, Barbora Peltanova, Hana Holcova Polanska, Martina Raudenska, Michal Masarik.

  One of the characteristics of cancer cells important for tumorigenesis is their metabolic plasticity. Indeed, in various stress conditions, cancer cells can reshape their metabolic pathways to support the increased energy request due to continuous growth and rapid proliferation. Moreover, selective pressures in the tumor microenvironment, such as hypoxia, acidosis, and competition for resources, force cancer cells to adapt by complete reorganization of their metabolism. In this review, we highlight the characteristics of cancer metabolism and discuss its clinical significance, since overcoming metabolic plasticity of cancer cells is a key objective of modern cancer therapeutics and a better understanding of metabolic reprogramming may lead to the identification of possible targets for cancer therapy.

Keywords:  Cancer metabolism; Cell death; Glutaminolysis; Metabolic symbiosis; Mitochondrial bioenergetics; Warburg effect

DOI:  https://doi.org/10.1016/j.bbcan.2022.188705
Cells. 2022 Feb 23. pii: 771. [Epub ahead of print]11(5):

Role of Mitochondrial Stress Response in Cancer Progression.

Yu Geon Lee, Do Hong Park, Young Chan Chae.

  Mitochondria are subcellular organelles that are a hub for key biological processes, such as bioenergetic, biosynthetic, and signaling functions. Mitochondria are implicated in all oncogenic processes, from malignant transformation to metastasis and resistance to chemotherapeutics. The harsh tumor environment constantly exposes cancer cells to cytotoxic stressors, such as nutrient starvation, low oxygen, and oxidative stress. Excessive or prolonged exposure to these stressors can cause irreversible mitochondrial damage, leading to cell death. To survive hostile microenvironments that perturb mitochondrial function, cancer cells activate a stress response to maintain mitochondrial protein and genome integrity. This adaptive mechanism, which is closely linked to mitochondrial function, enables rapid adjustment and survival in harsh environmental conditions encountered during tumor dissemination, thereby promoting cancer progression. In this review, we describe how the mitochondria stress response contributes to the acquisition of typical malignant traits and highlight the potential of targeting the mitochondrial stress response as an anti-cancer therapeutic strategy.

Keywords:  mitochondrial dynamics; mitochondrial protein quality control; mitochondrial stress response; mitophagy; mtDNA

DOI:  https://doi.org/10.3390/cells11050771
Front Pharmacol. 2022 ;13 768556

Molecular Docking as a Therapeutic Approach for Targeting Cancer Stem Cell Metabolic Processes.

Babak Arjmand, Shayesteh Kokabi Hamidpour, Sepideh Alavi-Moghadam, Hanieh Yavari, Ainaz Shahbazbadr, Mostafa Rezaei Tavirani, Kambiz Gilany, Bagher Larijani.

  Cancer stem cells (CSCs) are subpopulation of cells which have been demonstrated in a variety of cancer models and involved in cancer initiation, progression, and development. Indeed, CSCs which seem to form a small percentage of tumor cells, display resembling characteristics to natural stem cells such as self-renewal, survival, differentiation, proliferation, and quiescence. Moreover, they have some characteristics that eventually can demonstrate the heterogeneity of cancer cells and tumor progression. On the other hand, another aspect of CSCs that has been recognized as a central concern facing cancer patients is resistance to mainstays of cancer treatment such as chemotherapy and radiation. Owing to these details and the stated stemness capabilities, these immature progenitors of cancerous cells can constantly persist after different therapies and cause tumor regrowth or metastasis. Further, in both normal development and malignancy, cellular metabolism and stemness are intricately linked and CSCs dominant metabolic phenotype changes across tumor entities, patients, and tumor subclones. Hence, CSCs can be determined as one of the factors that correlate to the failure of common therapeutic approaches in cancer treatment. In this context, researchers are searching out new alternative or complementary therapies such as targeted methods to fight against cancer. Molecular docking is one of the computational modeling methods that has a new promise in cancer cell targeting through drug designing and discovering programs. In a simple definition, molecular docking methods are used to determine the metabolic interaction between two molecules and find the best orientation of a ligand to its molecular target with minimal free energy in the formation of a stable complex. As a comprehensive approach, this computational drug design method can be thought more cost-effective and time-saving compare to other conventional methods in cancer treatment. In addition, increasing productivity and quality in pharmaceutical research can be another advantage of this molecular modeling method. Therefore, in recent years, it can be concluded that molecular docking can be considered as one of the novel strategies at the forefront of the cancer battle via targeting cancer stem cell metabolic processes.

Keywords:  cancer; cancer stem cells; drug designing; metabolic processes; molecular docking

DOI:  https://doi.org/10.3389/fphar.2022.768556
Autophagy. 2022 Mar 08. 1-18

Mitochondrial respiration supports autophagy to provide stress resistance during quiescence.

Silvia Magalhaes-Novais, Jan Blecha, Ravindra Naraine, Jana Mikesova, Pavel Abaffy, Alena Pecinova, Mirko Milosevic, Romana Bohuslavova, Jan Prochazka, Shawez Khan, Eliska Novotna, Radek Sindelka, Radek Machan, Mieke Dewerchin, Erik Vlcak, Joanna Kalucka, Sona Stemberkova Hubackova, Ales Benda, Jermaine Goveia, Tomas Mracek, Cyril Barinka, Peter Carmeliet, Jiri Neuzil, Katerina Rohlenova, Jakub Rohlena.

  Mitochondrial oxidative phosphorylation (OXPHOS) generates ATP, but OXPHOS also supports biosynthesis during proliferation. In contrast, the role of OXPHOS during quiescence, beyond ATP production, is not well understood. Using mouse models of inducible OXPHOS deficiency in all cell types or specifically in the vascular endothelium that negligibly relies on OXPHOS-derived ATP, we show that selectively during quiescence OXPHOS provides oxidative stress resistance by supporting macroautophagy/autophagy. Mechanistically, OXPHOS constitutively generates low levels of endogenous ROS that induce autophagy via attenuation of ATG4B activity, which provides protection from ROS insult. Physiologically, the OXPHOS-autophagy system (i) protects healthy tissue from toxicity of ROS-based anticancer therapy, and (ii) provides ROS resistance in the endothelium, ameliorating systemic LPS-induced inflammation as well as inflammatory bowel disease. Hence, cells acquired mitochondria during evolution to profit from oxidative metabolism, but also built in an autophagy-based ROS-induced protective mechanism to guard against oxidative stress associated with OXPHOS function during quiescence.Abbreviations: AMPK: AMP-activated protein kinase; AOX: alternative oxidase; Baf A: bafilomycin A1; CI, respiratory complexes I; DCF-DA: 2',7'-dichlordihydrofluorescein diacetate; DHE: dihydroethidium; DSS: dextran sodium sulfate; ΔΨmi: mitochondrial inner membrane potential; EdU: 5-ethynyl-2'-deoxyuridine; ETC: electron transport chain; FA: formaldehyde; HUVEC; human umbilical cord endothelial cells; IBD: inflammatory bowel disease; LC3B: microtubule associated protein 1 light chain 3 beta; LPS: lipopolysaccharide; MEFs: mouse embryonic fibroblasts; MTORC1: mechanistic target of rapamycin kinase complex 1; mtDNA: mitochondrial DNA; NAC: N-acetyl cysteine; OXPHOS: oxidative phosphorylation; PCs: proliferating cells; PE: phosphatidylethanolamine; PEITC: phenethyl isothiocyanate; QCs: quiescent cells; ROS: reactive oxygen species; PLA2: phospholipase A2, WB: western blot.

Keywords:  ATG4B; biosynthesis; cell death; electron transport chain; endothelial cells; mitochondria; oxidative phosphorylation; oxidative stress; reactive oxygen species

DOI:  https://doi.org/10.1080/15548627.2022.2038898
Biomed Chromatogr. 2022 Mar 10. e5367

Metabolomics analysis reveals Oct4 overexpression drives metabolic reprogramming and enhanced glycolysis and pentose phosphate pathway in lung adenocarcinoma cells.

Yabin Tang, Liang Zhu, Hongzhuan Chen, Shuang Meng.

  Poor prognosis in the underlying mechanisms involved in lung adenocarcinoma and its treatment leads to low survival rates in patients. Emerging evidence indicates that cancer is primarily a metabolic disease and metabolic reprogramming is a well-established hallmark and driving force of cancer. Oct4, acting as an oncogene, is a major regulator of cell pluripotency. It can reprogram the differentiated cells into cancer stem cells (CSCs) and plays an oncogenic role when pathologically hijacked. However, data that Oct4, the genetic reprogramming factor, could induce metabolic reprogramming has been very limited and the direct evidence in metabolic level whether Oct4 reprograms metabolome is lacking. In the present study, integrated untargeted and targeted metabolomics analyses were utilized to investigate metabolic changes induced by Oct4 overexpression in lung adenocarcinoma cells. The results suggested that elevated expression levels of Oct4 drives metabolic reprogramming. Oct4 overexpression redirects glucose catabolism to glycolysis pathway and to the oxidative pentose phosphate pathway (PPP). This study identifies unique pathways that are candidate therapeutic targets for the treatment of lung adenocarcinoma. This study also aims to improve our understanding of the cancer-promoting activity of Oct4 and help identify novel diagnostic and therapeutic strategies for cancer treatment.

Keywords:  Oct4; lung adenocarcinoma; metabolic reprogramming; metabolomics

DOI:  https://doi.org/10.1002/bmc.5367
EMBO Mol Med. 2022 Mar 07. e14990

CDK7/12/13 inhibition targets an oscillating leukemia stem cell network and synergizes with venetoclax in acute myeloid leukemia.

Lixiazi He, Christian Arnold, Judith Thoma, Christian Rohde, Maksim Kholmatov, Swati Garg, Cheng-Chih Hsiao, Linda Viol, Kaiqing Zhang, Rui Sun, Christina Schmidt, Maike Janssen, Tara MacRae, Karin Huber, Christian Thiede, Josée Hébert, Guy Sauvageau, Julia Spratte, Herbert Fluhr, Gabriela Aust, Carsten Müller-Tidow, Christof Niehrs, Gislene Pereira, Jörg Hamann, Motomu Tanaka, Judith B Zaugg, Caroline Pabst.

  The heterogeneous response of acute myeloid leukemia (AML) to current anti-leukemic therapies is only partially explained by mutational heterogeneity. We previously identified GPR56 as a surface marker associated with poor outcome across genetic groups, which characterizes two leukemia stem cell (LSC)-enriched compartments with different self-renewal capacities. How these compartments self-renew remained unclear. Here, we show that GPR56+ LSC compartments are promoted in a complex network involving epithelial-to-mesenchymal transition (EMT) regulators besides Rho, Wnt, and Hedgehog (Hh) signaling. Unexpectedly, Wnt pathway inhibition increased the more immature, slowly cycling GPR56+ CD34+ fraction and Hh/EMT gene expression, while Wnt activation caused opposite effects. Our data suggest that the crucial role of GPR56 lies in its ability to co-activate these opposing signals, thus ensuring the constant supply of both LSC subsets. We show that CDK7 inhibitors suppress both LSC-enriched subsets in vivo and synergize with the Bcl-2 inhibitor venetoclax. Our data establish reciprocal transition between LSC compartments as a novel concept underlying the poor outcome in GPR56high AML and propose combined CDK7 and Bcl-2 inhibition as LSC-directed therapy in this disease.

Keywords:  AML; CDK7 inhibition; GPR56; leukemia stem cell; self-renewal

DOI:  https://doi.org/10.15252/emmm.202114990
Acta Pharm Sin B. 2022 Feb;12(2): 759-773

Targeting glutamine utilization to block metabolic adaptation of tumor cells under the stress of carboxyamidotriazole-induced nutrients unavailability.

Jing Shi, Rui Ju, Hongting Gao, Yuqing Huang, Lei Guo, Dechang Zhang.

  Tumor cells have unique metabolic programming that is biologically distinct from that of corresponding normal cells. Resetting tumor metabolic programming is a promising strategy to ameliorate drug resistance and improve the tumor microenvironment. Here, we show that carboxyamidotriazole (CAI), an anticancer drug, can function as a metabolic modulator that decreases glucose and lipid metabolism and increases the dependency of colon cancer cells on glutamine metabolism. CAI suppressed glucose and lipid metabolism utilization, causing inhibition of mitochondrial respiratory chain complex I, thus producing reactive oxygen species (ROS). In parallel, activation of the aryl hydrocarbon receptor (AhR) increased glutamine uptake via the transporter SLC1A5, which could activate the ROS-scavenging enzyme glutathione peroxidase. As a result, combined use of inhibitors of GLS/GDH1, CAI could effectively restrict colorectal cancer (CRC) energy metabolism. These data illuminate a new antitumor mechanism of CAI, suggesting a new strategy for CRC metabolic reprogramming treatment.

Keywords:  2-NBDG, glucalogue 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose; ATP, adenosine triphosphate; AhR; AhR, aryl hydrocarbon receptor; CAI; CAI, carboxyamidotriazole; CHIP, chromatin immunoprecipitation; CRC, colorectal cancer; Colorectal cancer metabolism; DMF, 3′,4′-dimethoxyflavone; DNA, deoxyribonucleic acid; ECAR, extracellular acidification rate; FACS, flow cytometry; GDH1, glutamate dehydrogenase 1; GLS, glutaminase; GPx, glutathione peroxidase; GSH, glutathione; GSSG, oxidized glutathione; Glutamine metabolism; Glutaminolysis; Kyn, kynurenine; MT, mito-TEMPO; Metabolic reprogramming; Mito-Q, mitoquinone mesylate; Mitochondrial oxidative stress; OCR, oxygen consumption rate; Redox homeostasis; TCA, tricarboxylic acid; α-KG, α-ketoglutarate

DOI:  https://doi.org/10.1016/j.apsb.2021.07.008
Front Immunol. 2022 ;13 811144

Tumor Microenvironment in Acute Myeloid Leukemia: Adjusting Niches.

Thomas Menter, Alexandar Tzankov.

  Acute myeloid leukemias (AML) comprise a wide array of different entities, which have in common a rapid expansion of myeloid blast cells leading to displacement of normal hematopoietic cells and also disruption of the microenvironment in the bone marrow niches. Based on an insight into the complex cellular interactions in the bone marrow niches in non-neoplastic conditions in general, this review delineates the complex relationship between leukemic cells and reactive cells of the tumor microenvironment (TME) in AML. A special focus is directed on niche cells and various T-cell subsets as these also provide a potential therapeutic rationale considering e.g. immunomodulation. The TME of AML on the one hand plays a vital role for sustaining and promoting leukemogenesis but - on the other hand - it also has adverse effects on abnormal blasts developing into overt leukemia hindering their proliferation and potentially removing such cells. Thus, leukemic cells need to and develop strategies in order to manipulate the TME. Interference with those strategies might be of particular therapeutic potential since mechanisms of resistance related to tumor cell plasticity do not apply to it.

Keywords:  AML; T-cells ; TME; bone marrow niches; bone marrow stromal cells

DOI:  https://doi.org/10.3389/fimmu.2022.811144
J Cell Physiol. 2022 Mar 06.

Extrusion of mitochondria: Garbage clearance or cell-cell communication signals?

Konstantin G Lyamzaev, Roman A Zinovkin, Boris V Chernyak.

  Mitochondria are dynamic organelles that regulate various intracellular signaling pathways, including the mechanisms of programmed cell death, differentiation, inflammation, and so on. Mitochondria may be extruded as membrane enveloped or as free organelles during developmental processes, inflammatory activation, and in the process of "garbage clearance" of damaged mitochondria in postmitotic cells. Extracellular mitochondria can be engulfed by immune and nonimmune cells and trigger intracellular signaling leading to an inflammatory response. At the same time, it was reported that the release of extracellular vesicles containing mitochondria from mesenchymal stem cells contributes to their therapeutic anti-inflammatory effects. Numerous studies claim that engulfed mitochondria improve cellular bioenergetics, but this assumption requires further investigation. This review aims at a critical discussion of the mechanisms of mitochondrial extrusion in mammals, the reception of mitochondrial components, and the responses of recipient cells to extracellular mitochondria.

Keywords:  extracellular mitochondria; extracellular vesicles; mitochondria; mitophagy; quality control

DOI:  https://doi.org/10.1002/jcp.30711
RNA. 2022 Mar 07. pii: rna.079097.122. [Epub ahead of print]

Mito-FUNCAT-FACS reveals cellular heterogeneity in mitochondrial translation.

Yusuke Kimura, Hironori Saito, Tatsuya Osaki, Yasuhiro Ikegami, Taisei Wakigawa, Yoshiho Ikeuchi, Shintaro Iwasaki.

  Mitochondria possess their own genome that encodes components of oxidative phosphorylation (OXPHOS) complexes, and mitochondrial ribosomes within the organelle translate the mRNAs expressed from the mitochondrial genome. Given the differential OXPHOS activity observed in diverse cell types, cell growth conditions, and other circumstances, cellular heterogeneity in mitochondrial translation can be expected. Although individual protein products translated in mitochondria have been monitored, the lack of techniques that address the variation in overall mitochondrial protein synthesis in cell populations poses analytic challenges. Here, we adapted mitochondrial-specific fluorescent noncanonical amino acid tagging (FUNCAT) for use with fluorescence-activated cell sorting (FACS) and developed mito-FUNCAT-FACS. The click chemistry-compatible methionine analog L-homopropargylglycine (HPG) enabled the metabolic labeling of newly synthesized proteins. In the presence of cytosolic translation inhibitors, HPG was selectively incorporated into mitochondrial nascent proteins and conjugated to fluorophores via the click reaction (mito-FUNCAT). The application of in situ mito-FUNCAT to flow cytometry allowed us to separate changes in net mitochondrial translation activity from those of the organelle mass and detect variations in mitochondrial translation in cancer cells. Our approach provides a useful methodology for examining mitochondrial protein synthesis in individual cells.

Keywords:  FACS; FUNCAT; HPG; Mitochondria; Translation

DOI:  https://doi.org/10.1261/rna.079097.122
Blood. 2022 Mar 10. 139(10): 1435

Targeting vulnerabilities of adult T-cell leukemia.

Masao Matsuoka.

DOI: https://doi.org/10.1182/blood.2021014879