bims-mibica 2024-03-03 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024–03–03
29 papers selected by
Kelsey Fisher-Wellman, East Carolina University

Triaging of α-helical proteins to the mitochondrial outer membrane by distinct chaperone machinery based on substrate topology.
PKM2 diverts glycolytic flux in dependence on mitochondrial one-carbon cycle.
PMF-seq: a highly scalable screening strategy for linking genetics to mitochondrial bioenergetics.
A novel mitochondria-targeting DHODH inhibitor induces robust ferroptosis and alleviates immune suppression.
Metabolism-focused CRISPR screen unveils mitochondrial pyruvate carrier 1 as a critical driver for PARP inhibitor resistance in lung cancer.
Genetic and bioinformatic analyses reveal transcriptional networks underlying dual genomic coordination of mitochondrial biogenesis.
A novel synthesized cyclohexane-hydroxytyrosol derivative suppresses ovarian cancer cell growth through inducing ROS and blocking autophagic flux.
Venetoclax efficacy on acute myeloid leukemia is enhanced by the combination with butyrate.
Targeting mitochondrial bioenergetics by combination treatment with imatinib and dichloroacetate in human erythroleukemic K‑562 and colorectal HCT‑116 cancer cells.
Disrupting CD38-driven T cell dysfunction restores sensitivity to cancer immunotherapy.
Metformin reduces the clonal fitness of Dnmt3aR878H hematopoietic stem and progenitor cells by reversing their aberrant metabolic and epigenetic state.
FBXL4: safeguarding against mitochondrial depletion through suppression of mitophagy.
Cysteine protease inhibitor 1 promotes metastasis by mediating an oxidative phosphorylation/MEK/ERK axis in esophageal squamous carcinoma cancer.
circFAM193B interaction with PRMT6 regulates AML leukemia stem cells chemoresistance through altering the oxidative metabolism and lipid peroxidation.
Ferritin-mediated mitochondrial iron homeostasis is essential for the survival of hematopoietic stem cells and leukemic stem cells.
Most axonal mitochondria in cortical pyramidal neurons lack mitochondrial DNA and consume ATP.
Tom20 gates PINK1 activity and mediates its tethering of the TOM and TIM23 translocases upon mitochondrial stress.
AHR signaling pathway mediates mitochondrial oxidative phosphorylation which leads to cytarabine resistance.
Mitochondrial DNA competition: starving out the mutant genome.
The transcription factor ChREBP Orchestrates liver carcinogenesis by coordinating the PI3K/AKT signaling and cancer metabolism.
Reorganization of mitochondria-organelle interactions during postnatal development in skeletal muscle.
Cancer-associated fibroblast-derived acetate promotes pancreatic cancer development by altering polyamine metabolism via the ACSS2-SP1-SAT1 axis.
Quiescence enables unrestricted cell fate in naive embryonic stem cells.
Chemical inhibition of phosphatidylcholine biogenesis reveals its role in mitochondrial division.
Screening of CPT1A-Targeting Lipid Metabolism Modulators Using Mitochondrial Membrane Chromatography.
mitoTALEN reduces the mutant mtDNA load in neurons.
Novel sulfonamide-indolinone hybrids targeting mitochondrial respiration of breast cancer cells.
Comprehensive analysis of mitochondria-related genes indicates that PPP2R2B is a novel biomarker and promotes the progression of bladder cancer via Wnt signaling pathway.
A spatial map of hepatic mitochondria uncovers functional heterogeneity shaped by nutrient-sensing signaling.

Mol Cell. 2024 Feb 27. pii: S1097-2765(24)00095-9. [Epub ahead of print]

Triaging of α-helical proteins to the mitochondrial outer membrane by distinct chaperone machinery based on substrate topology.

Gayathri Muthukumar, Taylor A Stevens, Alison J Inglis, Theodore K Esantsi, Reuben A Saunders, Fabian Schulte, Rebecca M Voorhees, Alina Guna, Jonathan S Weissman.

  Mitochondrial outer membrane ⍺-helical proteins play critical roles in mitochondrial-cytoplasmic communication, but the rules governing the targeting and insertion of these biophysically diverse proteins remain unknown. Here, we first defined the complement of required mammalian biogenesis machinery through genome-wide CRISPRi screens using topologically distinct membrane proteins. Systematic analysis of nine identified factors across 21 diverse ⍺-helical substrates reveals that these components are organized into distinct targeting pathways that act on substrates based on their topology. NAC is required for the efficient targeting of polytopic proteins, whereas signal-anchored proteins require TTC1, a cytosolic chaperone that physically engages substrates. Biochemical and mutational studies reveal that TTC1 employs a conserved TPR domain and a hydrophobic groove in its C-terminal domain to support substrate solubilization and insertion into mitochondria. Thus, the targeting of diverse mitochondrial membrane proteins is achieved through topological triaging in the cytosol using principles with similarities to ER membrane protein biogenesis systems.

Keywords:  CRISPR; NAC; TTC1; cell biology; cytosolic targeting; genetic screens; membrane protein insertion; mitochondrial outer membrane; topology

DOI:  https://doi.org/10.1016/j.molcel.2024.01.028
Cell Rep. 2024 Feb 28. pii: S2211-1247(24)00196-7. [Epub ahead of print]43(3): 113868

PKM2 diverts glycolytic flux in dependence on mitochondrial one-carbon cycle.

Mohaned Benzarti, Laura Neises, Anais Oudin, Christina Krötz, Elodie Viry, Ernesto Gargiulo, Coralie Pulido, Maryse Schmoetten, Vitaly Pozdeev, Nadia I Lorenz, Michael W Ronellenfitsch, David Sumpton, Marc Warmoes, Christian Jaeger, Antoine Lesur, Björn Becker, Etienne Moussay, Jerome Paggetti, Simone P Niclou, Elisabeth Letellier, Johannes Meiser.

  Modeling tumor metabolism in vitro remains challenging. Here, we used galactose as an in vitro tool compound to mimic glycolytic limitation. In contrast to the established idea that high glycolytic flux reduces pyruvate kinase isozyme M2 (PKM2) activity to support anabolic processes, we have discovered that glycolytic limitation also affects PKM2 activity. Surprisingly, despite limited carbon availability and energetic stress, cells induce a near-complete block of PKM2 to divert carbons toward serine metabolism. Simultaneously, TCA cycle flux is sustained, and oxygen consumption is increased, supported by glutamine. Glutamine not only supports TCA cycle flux but also serine synthesis via distinct mechanisms that are directed through PKM2 inhibition. Finally, deleting mitochondrial one-carbon (1C) cycle reversed the PKM2 block, suggesting a potential formate-dependent crosstalk that coordinates mitochondrial 1C flux and cytosolic glycolysis to support cell survival and proliferation during nutrient-scarce conditions.

Keywords:  CP: Cancer; CP: Metabolism

DOI:  https://doi.org/10.1016/j.celrep.2024.113868
Nat Metab. 2024 Feb 27.

PMF-seq: a highly scalable screening strategy for linking genetics to mitochondrial bioenergetics.

Tsz-Leung To, Jason G McCoy, Naomi K Ostriker, Lev S Sandler, Carmen A Mannella, Vamsi K Mootha.

Our current understanding of mitochondrial organelle physiology has benefited from two broad approaches: classically, cuvette-based measurements with suspensions of isolated mitochondria, in which bioenergetic parameters are monitored acutely in response to respiratory chain substrates and inhibitors1-4, and more recently, highly scalable genetic screens for fitness phenotypes associated with coarse-grained properties of the mitochondrial state5-10. Here we introduce permeabilized-cell mitochondrial function sequencing (PMF-seq) to combine strengths of these two approaches to connect genes to detailed bioenergetic phenotypes. In PMF-seq, the plasma membranes within a pool of CRISPR mutagenized cells are gently permeabilized under conditions that preserve mitochondrial physiology, where detailed bioenergetics can be probed in the same way as with isolated organelles. Cells with desired bioenergetic parameters are selected optically using flow cytometry and subjected to next-generation sequencing. Using PMF-seq, we recover genes differentially required for mitochondrial respiratory chain branching and reversibility. We demonstrate that human D-lactate dehydrogenase specifically conveys electrons from D-lactate into cytochrome c to support mitochondrial membrane polarization. Finally, we screen for genetic modifiers of tBID, a pro-apoptotic protein that acts directly and acutely on mitochondria. We find the loss of the complex V assembly factor ATPAF2 acts as a genetic sensitizer of tBID's acute action. We anticipate that PMF-seq will be valuable for defining genes critical to the physiology of mitochondria and other organelles.

DOI: https://doi.org/10.1038/s42255-024-00994-0
Pharmacol Res. 2024 Feb 27. pii: S1043-6618(24)00059-8. [Epub ahead of print]202 107115

A novel mitochondria-targeting DHODH inhibitor induces robust ferroptosis and alleviates immune suppression.

Yongrui Hai, Renming Fan, Ting Zhao, Ruizhuo Lin, Junyan Zhuang, Aohua Deng, Shanshui Meng, Zhuang Hou, Gaofei Wei.

  Dihydroorotate dehydrogenase (DHODH)-mediated ferroptosis defense is a targetable vulnerability in cancer. Currently, only a few DHODH inhibitors have been utilized in clinical practice. To further enhance DHODH targeting, we introduced the mitochondrial targeting group triphenylphosphine (TPP) to brequinar (BRQ), a robust DHODH inhibitor, resulting in the creation of active molecule B2. This compound exhibits heightened anticancer activity, effectively inhibiting proliferation in various cancer cells, and restraining tumor growth in melanoma xenografts in mice. B2 achieves these effects by targeting DHODH, triggering the formation of reactive oxygen species (ROS), promoting mitochondrial lipid peroxidation, and inducing ferroptosis in B16F10 and A375 cells. Surprisingly, B2 significantly downregulates PD-L1 and alleviates immune suppression. Importantly, B2 exhibits no apparent adverse effects in mice. Collectively, these findings highlight that enhancing the mitochondrial targeting capability of the DHODH inhibitor is a promising therapeutic approach for melanoma treatment.

Keywords:  Anticancer; DHODH inhibitor; Ferroptosis; Melanoma; Mitochondrial-targeting

DOI:  https://doi.org/10.1016/j.phrs.2024.107115
Mol Carcinog. 2024 Feb 27.

Metabolism-focused CRISPR screen unveils mitochondrial pyruvate carrier 1 as a critical driver for PARP inhibitor resistance in lung cancer.

Takashi Furusawa, Renzo Cavero, Yue Liu, Haojian Li, Xia Xu, Thorkell Andresson, William Reinhold, Olivia White, Myriem Boufraqech, Thomas J Meyer, Oliver Hartmann, Markus E Diefenbacher, Yves Pommier, Urbain Weyemi.

  Homologous recombination (HR) and poly ADP-ribosylation are partially redundant pathways for the repair of DNA damage in normal and cancer cells. In cell lines that are deficient in HR, inhibition of poly (ADP-ribose) polymerase (poly (ADP-ribose) polymerase [PARP]1/2) is a proven target with several PARP inhibitors (PARPis) currently in clinical use. Resistance to PARPi often develops, usually involving genetic alterations in DNA repair signaling cascades, but also metabolic rewiring particularly in HR-proficient cells. We surmised that alterations in metabolic pathways by cancer drugs such as Olaparib might be involved in the development of resistance to drug therapy. To test this hypothesis, we conducted a metabolism-focused clustered regularly interspaced short palindromic repeats knockout screen to identify genes that undergo alterations during the treatment of tumor cells with PARPis. Of about 3000 genes in the screen, our data revealed that mitochondrial pyruvate carrier 1 (MPC1) is an essential factor in desensitizing nonsmall cell lung cancer (NSCLC) lung cancer lines to PARP inhibition. In contrast to NSCLC lung cancer cells, triple-negative breast cancer cells do not exhibit such desensitization following MPC1 loss and reprogram the tricarboxylic acid cycle and oxidative phosphorylation pathways to overcome PARPi treatment. Our findings unveil a previously unknown synergistic response between MPC1 loss and PARP inhibition in lung cancer cells.

Keywords:  CRISPR screen; DNA damage response; NSCLC; PARP inhibitor; breast cancer; metabolism

DOI:  https://doi.org/10.1002/mc.23705
bioRxiv. 2024 Jan 29. pii: 2024.01.25.577217. [Epub ahead of print]

Genetic and bioinformatic analyses reveal transcriptional networks underlying dual genomic coordination of mitochondrial biogenesis.

Fan Zhang, Annie Lee, Anna Freitas, Jake Herb, Zongheng Wang, Snigdha Gupta, Zhe Chen, Hong Xu.

Mitochondrial genome encodes handful genes of respiratory chain complexes, whereas all the remaining mitochondrial proteins are encoded on the nuclear genome. However, the mechanisms coordinating these two genomes to control mitochondrial biogenesis remain largely unknown. To identify transcription circuits involved in these processes, we performed a candidate RNAi screen in developing eyes that had reduced mitochondrial DNA contents. We reasoned that impaired mitochondrial biogenesis would synergistically interact with mtDNA deficiency in disrupting tissue development. Over 638 transcription factors annotated in the fly genome, we identified 77 transcription factors that may be involved in mitochondrial genome maintenance and gene expression. Additional genetic and genomic analyses revealed that a novel transcription factor, CG1603, and its upstream factor YL-1 are essential for mitochondrial biogenesis. We constructed a regulator network among positive hits using the published CHIP-seq data. The network analysis revealed extensive connections, and complex hierarchical organization underlying the transcription regulation of mitochondrial biogenesis.

DOI: https://doi.org/10.1101/2024.01.25.577217
Antioxid Redox Signal. 2024 Feb 26.

A novel synthesized cyclohexane-hydroxytyrosol derivative suppresses ovarian cancer cell growth through inducing ROS and blocking autophagic flux.

Guanfei Zhang, Min Wang, Yilin Gao, Aikaterini-Christina Komianou, Eleftheria A Georgiou, Yan Wang, Yezi Zheng, Jiankang Liu, Ioannis K Kostakis, Lin Zhao.

AIMS: Drug resistance in ovarian cancer (OC) cells often leads to recurrence, metastasis, and high mortality rates among OC patients. Hydroxytyrosol (HT) has been reported to inhibit the proliferation of ovarian and other types of cancer cells. Here we synthesized a novel cyclohexane-hydroxytyrosol derivative (Chx-HT) for enhanced anticaner efficacy. We examined the growth-suppressing effect of Chx-HT on OC cells in vitro and in xenograft mouse model and investigated the underlying mechanism.
RESULTS: We demonstrated that Chx-HT inhibits proliferation, promotes apoptosis, remodels glucose and lipid metabolism by reducing fatty acid β-oxidation while increasing glycolysis, de novo fatty acid synthesis and lipid droplet accumulation, impairs mitochondrial respiration and induces oxidative stress both in vitro and in vivo. Additionally, Chx-HT blocks autophagic flux by obstructing the maturation of lysosomal cathepsins in the late-stage, but also activates autophagy through the p-AMPK/p-mTOR/p-ULK1 pathway in response to energy deficit.
INNOVATION AND CONCLUSION: ROS plays a critical role in mediating the effects of Chx-HT on proliferation, apoptosis, autophagy, TCA cycle, FAO and mitochondrial respiration, and the autophagic activation underlies the effects of Chx-HT on glycolysis, de novo fatty acid synthesis, and lipid droplet accumulation in ovarian cancer cells. Cotreating OC cells with Chx-HT and autophagic inhibitor or glycolytic inhibitor results in an additive inhibition of proliferation. Our study indicates that Chx-HT stands for a promising OC therapeutic by ROS and autophagy blockade mediated metabolic remodeling.

DOI: https://doi.org/10.1089/ars.2023.0400
Sci Rep. 2024 Feb 29. 14(1): 4975

Venetoclax efficacy on acute myeloid leukemia is enhanced by the combination with butyrate.

Renshi Kawakatsu, Kenjiro Tadagaki, Kenta Yamasaki, Tatsushi Yoshida.

Venetoclax has been approved recently for treatment of Acute myeloid leukemia (AML). Venetoclax is a BH3-mimetic and induces apoptosis via Bcl-2 inhibition. However, venetoclax's effect is still restrictive and a novel strategy is needed. In the present study, we demonstrate that sodium butyrate (NaB) facilitates the venetoclax's efficacy of cell death in AML cells. As a single agent, NaB or venetoclax exerted just a weak effect on cell death induction for AML cell line KG-1. The combination with NaB and venetoclax drastically induced cell death. NaB upregulated pro-apoptotic factors, Bax and Bak, indicating the synergistic effect by the collaboration with Bcl-2 inhibition by venetoclax. The combined treatment with NaB and venetoclax strongly cleaved a caspase substrate poly (ADP-ribose) polymerase (PARP) and a potent pan-caspase inhibitor Q-VD-OPh almost completely blocked the cell death induced by the combination, meaning that the combination mainly induced apoptosis. The combination with NaB and venetoclax also strongly induced cell death in another AML cell line SKNO-1 but did not affect chronic myeloid leukemia (CML) cell line K562, indicating that the effect was specific for AML cells. Our results provide a novel strategy to strengthen the effect of venetoclax for AML treatment.

DOI: https://doi.org/10.1038/s41598-024-55286-0
Int J Oncol. 2024 Apr;pii: 42. [Epub ahead of print]64(4):

Targeting mitochondrial bioenergetics by combination treatment with imatinib and dichloroacetate in human erythroleukemic K‑562 and colorectal HCT‑116 cancer cells.

Maria G Kakafika, Areti A Lyta, George I Gavriilidis, Stefanos A Tsiftsoglou, Androulla N Miliotou, Ioannis S Pappas, Ioannis S Vizirianakis, Lefkothea C Papadopoulou, Asterios S Tsiftsoglou.

  Tumor malignant cells are characterized by dysregulation of mitochondrial bioenergetics due to the 'Warburg effect'. In the present study, this metabolic imbalance was explored as a potential target for novel cancer chemotherapy. Imatinib (IM) downregulates the expression levels of SCΟ2 and FRATAXIN (FXN) genes involved in the heme‑dependent cytochrome c oxidase biosynthesis and assembly pathway in human erythroleukemic IM‑sensitive K‑562 chronic myeloid leukemia cells (K‑562). In the present study, it was investigated whether the treatment of cancer cells with IM (an inhibitor of oxidative phosphorylation) separately, or together with dichloroacetate (DCA) (an inhibitor of glycolysis), can inhibit cell proliferation or cause death. Human K‑562 and IM‑chemoresistant K‑562 chronic myeloid leukemia cells (K‑562R), as well as human colorectal carcinoma cells HCT‑116 (+/+p53) and (‑/‑p53, with double TP53 knock-in disruptions), were employed. Treatments of these cells with either IM (1 or 2 µM) and/or DCA (4 mΜ) were also assessed for the levels of several process biomarkers including SCO2, FXN, lactate dehydrogenase A, glyceraldehyde‑3‑phosphate dehydrogenase, pyruvate kinase M2, hypoxia inducing factor‑1a, heme oxygenase‑1, NF‑κB, stem cell factor and vascular endothelial growth factor via western blot analysis. Computational network biology models were also applied to reveal the connections between the ten proteins examined. Combination treatment of IM with DCA caused extensive cell death (>75%) in K‑562 and considerable (>45%) in HCT‑116 (+/+p53) cultures, but less in K‑562R and HCT‑116 (‑/‑p53), with the latter deficient in full length p53 protein. Such treatment, markedly reduced reactive oxygen species levels, as measured by flow‑cytometry, in K‑562 cells and affected the oxidative phosphorylation and glycolytic biomarkers in all lines examined. These findings indicated, that targeting of cancer mitochondrial bioenergetics with such a combination treatment was very effective, although chemoresistance to IM in leukemia and the absence of a full length p53 in colorectal cells affected its impact.

Keywords:  HCT‑116; K‑562; Warburg effect; bioenergetics; cancer; dichloroacetate; imatinib; mitochondria

DOI:  https://doi.org/10.3892/ijo.2024.5630
bioRxiv. 2024 Feb 17. pii: 2024.02.12.579184. [Epub ahead of print]

Disrupting CD38-driven T cell dysfunction restores sensitivity to cancer immunotherapy.

Or-Yam Revach, Angelina M Cicerchia, Ofir Shorer, Boryana Petrova, Seth Anderson, Josh Park, Lee Chen, Arnav Mehta, Samuel J Wright, Niamh McNamee, Aya Tal-Mason, Giulia Cattaneo, Payal Tiwari, Hongyan Xie, Johanna M Sweere, Li-Chun Cheng, Natalia Sigal, Elizabeth Enrico, Marisa Miljkovic, Shane A Evans, Ngan Nguyen, Mark E Whidden, Ramji Srinivasan, Matthew H Spitzer, Yi Sun, Tatyana Sharova, Aleigha Lawless, William A Michaud, Martin Q Rasmussen, Jacy Fang, Claire Palin, Feng Chen, Xinhui Wang, Cristina R Ferrone, Donald P Lawrence, Ryan J Sullivan, David Liu, Uma M Sachdeva, Debattama R Sen, Keith T Flaherty, Robert T Manguso, Lloyd Bod, Manolis Kellis, Genevieve M Boland, Keren Yizhak, Jiekun Yang, Naama Kanarek, Moshe Sade-Feldman, Nir Hacohen, Russell W Jenkins.

A central problem in cancer immunotherapy with immune checkpoint blockade (ICB) is the development of resistance, which affects 50% of patients with metastatic melanoma. T cell exhaustion, resulting from chronic antigen exposure in the tumour microenvironment, is a major driver of ICB resistance. Here, we show that CD38, an ecto-enzyme involved in nicotinamide adenine dinucleotide (NAD+) catabolism, is highly expressed in exhausted CD8+ T cells in melanoma and is associated with ICB resistance. Tumour-derived CD38hiCD8+ T cells are dysfunctional, characterised by impaired proliferative capacity, effector function, and dysregulated mitochondrial bioenergetics. Genetic and pharmacological blockade of CD38 in murine and patient-derived organotypic tumour models (MDOTS/PDOTS) enhanced tumour immunity and overcame ICB resistance. Mechanistically, disrupting CD38 activity in T cells restored cellular NAD+ pools, improved mitochondrial function, increased proliferation, augmented effector function, and restored ICB sensitivity. Taken together, these data demonstrate a role for the CD38-NAD+ axis in promoting T cell exhaustion and ICB resistance, and establish the efficacy of CD38 directed therapeutic strategies to overcome ICB resistance using clinically relevant, patient-derived 3D tumour models.

DOI: https://doi.org/10.1101/2024.02.12.579184
Res Sq. 2024 Feb 06. pii: rs.3.rs-3874821. [Epub ahead of print]

Metformin reduces the clonal fitness of Dnmt3aR878H hematopoietic stem and progenitor cells by reversing their aberrant metabolic and epigenetic state.

Steven Chan, Mohsen Hosseini, Veronique Voisin, Ali Chegini, Angelica Varesi, Severine Cathelin, Dhanoop Manikoth Ayyathan, Alex Liu, Yitong Yang, Vivian Wang, Abdula Maher, Eric Grignano, Julie Haines, Angelo D'Alessandro, Kira Young, Yiyan Wu, Martina Fiumara, Samuele Ferrari, Luigi Naldini, Federico Gaiti, Shraddha Pai, Aaron Schimmer, Gary Bader, John Dick, Stephanie Z Xie, Jennifer Trowbridge.

Clonal hematopoiesis (CH) arises when a hematopoietic stem cell (HSC) acquires a mutation that confers a competitive advantage over wild-type (WT) HSCs, resulting in its clonal expansion. Individuals with CH are at an increased risk of developing hematologic neoplasms and a range of age-related inflammatory illnesses1-3. Therapeutic interventions that suppress the expansion of mutant HSCs have the potential to prevent these CH-related illnesses; however, such interventions have not yet been identified. The most common CH driver mutations are in the DNA methyltransferase 3 alpha (DNMT3A) gene with arginine 882 (R882) being a mutation hotspot. Here we show that murine hematopoietic stem and progenitor cells (HSPCs) carrying the Dnmt3aR878H/+ mutation, which is equivalent to human DNMT3AR882H/+, have increased mitochondrial respiration compared with WT cells and are dependent on this metabolic reprogramming for their competitive advantage. Importantly, treatment with metformin, an oral anti-diabetic drug with inhibitory activity against complex I in the electron transport chain (ETC), reduced the fitness of Dnmt3aR878H/+ HSCs. Through a multi-omics approach, we discovered that metformin acts by enhancing the methylation potential in Dnmt3aR878H/+ HSPCs and reversing their aberrant DNA CpG methylation and histone H3K27 trimethylation (H3K27me3) profiles. Metformin also reduced the fitness of human DNMT3AR882H HSPCs generated by prime editing. Our findings provide preclinical rationale for investigating metformin as a preventive intervention against illnesses associated with DNMT3AR882 mutation-driven CH in humans.

DOI: https://doi.org/10.21203/rs.3.rs-3874821/v1
Autophagy. 2024 Feb 29. 1-3

FBXL4: safeguarding against mitochondrial depletion through suppression of mitophagy.

Prajakta Kulkarni, Giang Thanh Nguyen-Dien, Keri-Lyn Kozul, Julia K Pagan.

  Mitophagy is a critical mitochondrial quality control process that selectively removes dysfunctional or excess mitochondria through the autophagy-lysosome system. The process is tightly controlled to ensure cellular and physiological homeostasis. Insufficient mitophagy can result in failure to remove damaged mitochondria and consequent cellular degeneration, but it is equally important to appropriately restrain mitophagy to prevent excessive mitochondrial depletion. Here, we discuss our recent discovery that the SKP1-CUL1-F-box (SCF)-FBXL4 (F-box and leucine-rich repeat protein 4) E3 ubiquitin ligase localizes to the mitochondrial outer membrane, where it constitutively mediates the ubiquitination and degradation of BNIP3L/NIX and BNIP3 mitophagy receptors to suppress mitophagy. The post-translational regulation of BNIP3L and BNIP3 is disrupted in mitochondrial DNA depletion syndrome 13 (MTDPS13), a multi-systemic disorder caused by mutations in the FBXL4 gene and characterized by elevated mitophagy and mitochondrial DNA/mtDNA depletion in patient fibroblasts. Our results demonstrate that mitophagy is not solely stimulated in response to specific conditions but is instead also actively suppressed through the continuous degradation of BNIP3L and BNIP3 mediated by the SCF-FBXL4 ubiquitin ligase. Thus, cellular conditions or signaling events that prevent the FBXL4-mediated turnover of BNIP3L and BNIP3 on specific mitochondria are expected to facilitate their selective removal.

Keywords:  BNIP3; BNIP3L/NIX; FBXL4; MTDPS13; mitophagy; ubiquitin ligase

DOI:  https://doi.org/10.1080/15548627.2024.2318077
Sci Rep. 2024 Feb 29. 14(1): 4985

Cysteine protease inhibitor 1 promotes metastasis by mediating an oxidative phosphorylation/MEK/ERK axis in esophageal squamous carcinoma cancer.

Liangming Zhang, Xiongfeng Chen, Jianwei Wang, Meihong Chen, Juan Chen, Wanzhen Zhuang, Yu Xia, Zhixin Huang, Yue Zheng, Yi Huang.

  Cysteine protease inhibitor 1 (CST1) is a cystatin superfamily protein that inhibits cysteine protease activity and is reported to be involved in the development of many malignancies. Mitochondrial oxidative phosphorylation (OXPHOS) also plays an important role in cancer cell growth regulation. However, the relationship and roles of CST1 and OXPHOS in esophageal squamous cell carcinoma (ESCC) remains unclear. In our pilot study, CST1 was shown the potential of promoting ESCC migration and invasion by the activation of MEK/ERK pathway. Transcriptome sequencing analysis revealed that CST1 is closely associated with OXPHOS. Based on a real-time ATP rate assay, mitochondrial complex I enzyme activity assay, immunofluorescence, co-immunoprecipitation, and addition of the OXPHOS inhibitor Rotenone and MEK/ERK inhibitor PD98059, we determined that CST1 affects mitochondrial complex I enzyme activity by interacting with the GRIM19 protein to elevate OXPHOS levels, and a reciprocal regulatory relationship exists between OXPHOS and the MEK/ERK pathway in ESCC cells. Finally, an in vivo study demonstrated the potential of CST1 in ESCC metastasis through regulation of the OXPHOS and MEK/ERK pathways. This study is the first to reveal the oncogenic role of CST1 in ESCC development by enhancing mitochondrial respiratory chain complex I activity to activate the OXPHOS/MEK/ERK axis, and then promote ESCC metastasis, suggesting that CST1/OXPHOS is a promising target for ESCC treatment.

Keywords:  CST1; Esophageal squamous cell carcinoma; MEK/ERK pathway; Oxidative phosphorylation

DOI:  https://doi.org/10.1038/s41598-024-55544-1
Leukemia. 2024 Feb 29.

circFAM193B interaction with PRMT6 regulates AML leukemia stem cells chemoresistance through altering the oxidative metabolism and lipid peroxidation.

Xinyu Yang, Jinting Liu, Wancheng Liu, Hanyang Wu, Yihong Wei, Xiaodong Guo, Hexiao Jia, Can Can, Dongmei Wang, Xiang Hu, Daoxin Ma.

Most forms of chemotherapy for acute myeloid leukemia (AML) are often ineffective in eliminating leukemic stem cells (LSCs), as their underlying mechanisms remain unclear. Here, we have identified circFAM193B, which regulates the redox biology of LSCs and is associated with unfavorable outcomes in AML patients. In vitro and in vivo assays suggested that circFAM193B significantly inhibits LSCs chemotherapy resistance and AML progression. Knockdown circFAM193B enhances mitochondrial OXPHOS function and inhibits the accumulation of reactive oxygen species and lipid peroxidation mediated by chemotherapy, which protects AML cells from oxidative stress-induced cell death. Mechanistically, circFAM193B physically interacts with arginine methyltransferase PRMT6 catalytic domain and enhances the transcription efficiency of key lipid peroxidation factor ALOX15 by decreasing H3R2me2a modification. In summary, we have identified circFAM193B was downregulated in LSCs to promote the survival of LSC by modulating energy metabolism and the redox balance in the postchemotherapy persistence of LSC. Our studies provide a conceptual advance and biological insights regarding the drug resistance of LSCs via circRNA mediated PRMT6-deposited methylarginine signaling.

DOI: https://doi.org/10.1038/s41375-024-02189-8
Leukemia. 2024 Feb 24.

Ferritin-mediated mitochondrial iron homeostasis is essential for the survival of hematopoietic stem cells and leukemic stem cells.

Weiwei Yi, Jinhua Zhang, Yingxin Huang, Qiang Zhan, Mi Zou, Xiang Cheng, Xuguang Zhang, Zhinan Yin, Si Tao, Hui Cheng, Fudi Wang, Jun Guo, Zhenyu Ju, Zhiyang Chen.

Iron metabolism plays a crucial role in cell viability, but its relationship with adult stem cells and cancer stem cells is not fully understood. The ferritin complex, responsible for intracellular iron storage, is important in this process. We report that conditional deletion of ferritin heavy chain 1 (Fth1) in the hematopoietic system reduced the number and repopulation capacity of hematopoietic stem cells (HSCs). These effects were associated with a decrease in cellular iron level, leading to impaired mitochondrial function and the initiation of apoptosis. Iron supplementation, antioxidant, and apoptosis inhibitors reversed the reduced cell viability of Fth1-deleted hematopoietic stem and progenitor cells (HSPCs). Importantly, leukemic stem cells (LSCs) derived from MLL-AF9-induced acute myeloid leukemia (AML) mice exhibited reduced Fth1 expression, rendering them more susceptible to apoptosis induced by the iron chelation compared to normal HSPCs. Modulating FTH1 expression using mono-methyl fumarate increased LSCs resistance to iron chelator-induced apoptosis. Additionally, iron supplementation, antioxidant, and apoptosis inhibitors protected LSCs from iron chelator-induced cell death. Fth1 deletion also extended the survival of AML mice. These findings unveil a novel mechanism by which ferritin-mediated iron homeostasis regulates the survival of both HSCs and LSCs, suggesting potential therapeutic strategies for blood cancer with iron dysregulation.

DOI: https://doi.org/10.1038/s41375-024-02169-y
bioRxiv. 2024 Feb 13. pii: 2024.02.12.579972. [Epub ahead of print]

Most axonal mitochondria in cortical pyramidal neurons lack mitochondrial DNA and consume ATP.

Yusuke Hirabayashi, Tommy L Lewis, Yudan Du, Daniel M Virga, Aubrianna M Decker, Giovanna Coceano, Jonatan Alvelid, Maëla A Paul, Stevie Hamilton, Parker Kneis, Yasufumi Takahashi, Jellert T Gaublomme, Ilaria Testa, Franck Polleux.

In neurons of the mammalian central nervous system (CNS), axonal mitochondria are thought to be indispensable for supplying ATP during energy-consuming processes such as neurotransmitter release. Here, we demonstrate using multiple, independent, in vitro and in vivo approaches that the majority (~80-90%) of axonal mitochondria in cortical pyramidal neurons (CPNs), lack mitochondrial DNA (mtDNA). Using dynamic, optical imaging analysis of genetically encoded sensors for mitochondrial matrix ATP and pH, we demonstrate that in axons of CPNs, but not in their dendrites, mitochondrial complex V (ATP synthase) functions in a reverse way, consuming ATP and protruding H+ out of the matrix to maintain mitochondrial membrane potential. Our results demonstrate that in mammalian CPNs, axonal mitochondria do not play a major role in ATP supply, despite playing other functions critical to regulating neurotransmission such as Ca2+ buffering.

DOI: https://doi.org/10.1101/2024.02.12.579972
Proc Natl Acad Sci U S A. 2024 Mar 05. 121(10): e2313540121

Tom20 gates PINK1 activity and mediates its tethering of the TOM and TIM23 translocases upon mitochondrial stress.

Mohamed A Eldeeb, Andrew N Bayne, Armaan Fallahi, Thomas Goiran, Emma J MacDougall, Andrea Soumbasis, Cornelia E Zorca, Jace-Jones Tabah, Rhalena A Thomas, Nathan Karpilovsky, Meghna Mathur, Thomas M Durcan, Jean-François Trempe, Edward A Fon.

  Mutations in PTEN-induced putative kinase 1 (PINK1) cause autosomal recessive early-onset Parkinson's disease (PD). PINK1 is a Ser/Thr kinase that regulates mitochondrial quality control by triggering mitophagy mediated by the ubiquitin (Ub) ligase Parkin. Upon mitochondrial damage, PINK1 accumulates on the outer mitochondrial membrane forming a high-molecular-weight complex with the translocase of the outer membrane (TOM). PINK1 then phosphorylates Ub, which enables recruitment and activation of Parkin followed by autophagic clearance of the damaged mitochondrion. Thus, Parkin-dependent mitophagy hinges on the stable accumulation of PINK1 on the TOM complex. Yet, the mechanism linking mitochondrial stressors to PINK1 accumulation and whether the translocases of the inner membrane (TIMs) are also involved remain unclear. Herein, we demonstrate that mitochondrial stress induces the formation of a PINK1-TOM-TIM23 supercomplex in human cultured cell lines, dopamine neurons, and midbrain organoids. Moreover, we show that PINK1 is required to stably tether the TOM to TIM23 complexes in response to stress such that the supercomplex fails to accumulate in cells lacking PINK1. This tethering is dependent on an interaction between the PINK1 N-terminal-C-terminal extension module and the cytosolic domain of the Tom20 subunit of the TOM complex, the disruption of which, by either designer or PD-associated PINK1 mutations, inhibits downstream mitophagy. Together, the findings provide key insight into how PINK1 interfaces with the mitochondrial import machinery, with important implications for the mechanisms of mitochondrial quality control and PD pathogenesis.

Keywords:  PINK1; mitochondrial import; mitochondrial quality control; mitophagy; proteolysis

DOI:  https://doi.org/10.1073/pnas.2313540121
Acta Biochim Biophys Sin (Shanghai). 2024 Feb 26.

AHR signaling pathway mediates mitochondrial oxidative phosphorylation which leads to cytarabine resistance.

Yan Jia, Xiyu Li, Lulu Chen, Ling Li, Suzhen Zhang, Wenhui Huang, Hao Zhang.

  The aryl hydrocarbon receptor (AHR) has been identified as a significant driver of tumorigenesis. However, its clinical significance in acute myeloid leukemia (AML) remains largely unclear. In this study, RNA-Seq data from AML patients (bone marrow samples from 173 newly diagnosed AML patients) obtained from the TCGA database, and normal human RNA-Seq data (bone marrow samples from 70 healthy individuals) obtained from the GTEX database are downloaded for external validation and complementarity. The data analysis reveals that the AHR signaling pathway is activated in AML patients. Furthermore, there is a correlation between the expressions of AHR and mitochondrial oxidative phosphorylation genes. In vitro experiments show that enhancing AHR expression in AML cells increases mitochondrial oxidative phosphorylation and induces resistance to cytarabine. Conversely, reducing AHR expression in AML cells decreases cytarabine resistance. These findings deepen our understanding of the AHR signaling pathway's involvement in AML.

Keywords:  AHR expression; AML; cytarabine resistance; mitochondrial oxidative phosphorylation

DOI:  https://doi.org/10.3724/abbs.2024022
Trends Pharmacol Sci. 2024 Feb 23. pii: S0165-6147(24)00024-5. [Epub ahead of print]

Mitochondrial DNA competition: starving out the mutant genome.

Antonella Spinazzola, Diego Perez-Rodriguez, Jan Ježek, Ian J Holt.

  High levels of pathogenic mitochondrial DNA (mtDNA) variants lead to severe genetic diseases, and the accumulation of such mutants may also contribute to common disorders. Thus, selecting against these mutants is a major goal in mitochondrial medicine. Although mutant mtDNA can drift randomly, mounting evidence indicates that active forces play a role in the selection for and against mtDNA variants. The underlying mechanisms are beginning to be clarified, and recent studies suggest that metabolic cues, including fuel availability, contribute to shaping mtDNA heteroplasmy. In the context of pathological mtDNAs, remodeling of nutrient metabolism supports mitochondria with deleterious mtDNAs and enables them to outcompete functional variants owing to a replicative advantage. The elevated nutrient requirement represents a mutant Achilles' heel because small molecules that restrict nutrient consumption or interfere with nutrient sensing can purge cells of deleterious mtDNAs and restore mitochondrial respiration. These advances herald the dawn of a new era of small-molecule therapies to counteract pathological mtDNAs.

Keywords:  2-Deoxy-d-glucose; epigenetic rewiring; heteroplasmy; mitochondrial DNA; nutrient metabolism; nutrient signaling

DOI:  https://doi.org/10.1016/j.tips.2024.01.011
Nat Commun. 2024 Feb 29. 15(1): 1879

The transcription factor ChREBP Orchestrates liver carcinogenesis by coordinating the PI3K/AKT signaling and cancer metabolism.

Emmanuel Benichou, Bolaji Seffou, Selin Topçu, Ophélie Renoult, Véronique Lenoir, Julien Planchais, Caroline Bonner, Catherine Postic, Carina Prip-Buus, Claire Pecqueur, Sandra Guilmeau, Marie-Clotilde Alves-Guerra, Renaud Dentin.

Cancer cells integrate multiple biosynthetic demands to drive unrestricted proliferation. How these cellular processes crosstalk to fuel cancer cell growth is still not fully understood. Here, we uncover the mechanisms by which the transcription factor Carbohydrate responsive element binding protein (ChREBP) functions as an oncogene during hepatocellular carcinoma (HCC) development. Mechanistically, ChREBP triggers the expression of the PI3K regulatory subunit p85α, to sustain the activity of the pro-oncogenic PI3K/AKT signaling pathway in HCC. In parallel, increased ChREBP activity reroutes glucose and glutamine metabolic fluxes into fatty acid and nucleic acid synthesis to support PI3K/AKT-mediated HCC growth. Thus, HCC cells have a ChREBP-driven circuitry that ensures balanced coordination between PI3K/AKT signaling and appropriate cell anabolism to support HCC development. Finally, pharmacological inhibition of ChREBP by SBI-993 significantly suppresses in vivo HCC tumor growth. Overall, we show that targeting ChREBP with specific inhibitors provides an attractive therapeutic window for HCC treatment.

DOI: https://doi.org/10.1038/s41467-024-45548-w
J Physiol. 2024 Mar 01.

Reorganization of mitochondria-organelle interactions during postnatal development in skeletal muscle.

Yuho Kim, Hailey A Parry, T Bradley Willingham, Greg Alspaugh, Eric Lindberg, Christian A Combs, Jay R Knutson, Christopher K E Bleck, Brian Glancy.

  Skeletal muscle cellular development requires the integrated assembly of mitochondria and other organelles adjacent to the sarcomere in support of muscle contractile performance. However, it remains unclear how interactions among organelles and with the sarcomere relates to the development of muscle cell function. Here, we combine 3D volume electron microscopy, proteomic analyses, and live cell functional imaging to investigate the postnatal reorganization of mitochondria-organelle interactions in skeletal muscle. We show that while mitochondrial networks are disorganized and loosely associated with the contractile apparatus at birth, contact sites among mitochondria, lipid droplets and the sarcoplasmic reticulum are highly abundant in neonatal muscles. The maturation process is characterized by a transition to highly organized mitochondrial networks wrapped tightly around the muscle sarcomere but also to less frequent interactions with both lipid droplets and the sarcoplasmic reticulum. Concomitantly, expression of proteins involved in mitochondria-organelle membrane contact sites decreases during postnatal development in tandem with a decrease in abundance of proteins associated with sarcomere assembly despite an overall increase in contractile protein abundance. Functionally, parallel measures of mitochondrial membrane potential, NADH redox status, and NADH flux within intact cells revealed that mitochondria in adult skeletal muscle fibres maintain a more activated electron transport chain compared with neonatal muscle mitochondria. These data demonstrate a developmental redesign reflecting a shift from muscle cell assembly and frequent inter-organelle communication toward a muscle fibre with mitochondrial structure, interactions, composition and function specialized to support contractile function. KEY POINTS: Mitochondrial network organization is remodelled during skeletal muscle postnatal development. The mitochondrial outer membrane is in frequent contact with other organelles at birth and transitions to more close associations with the contractile apparatus in mature muscles. Mitochondrial energy metabolism becomes more activated during postnatal development. Understanding the developmental redesign process within skeletal muscle cells may help pinpoint specific areas of deficit in muscles with developmental disorders.

Keywords:  3D mitochondrial structure; functional cellular imaging; organelle interactions; postnatal muscle development; volume electron microscopy

DOI:  https://doi.org/10.1113/JP285014
Nat Cell Biol. 2024 Mar 01.

Cancer-associated fibroblast-derived acetate promotes pancreatic cancer development by altering polyamine metabolism via the ACSS2-SP1-SAT1 axis.

Divya Murthy, Kuldeep S Attri, Surendra K Shukla, Ravi Thakur, Nina V Chaika, Chunbo He, Dezhen Wang, Kanupriya Jha, Aneesha Dasgupta, Ryan J King, Scott E Mulder, Joshua Souchek, Teklab Gebregiworgis, Vikant Rai, Rohit Patel, Tuo Hu, Sandeep Rana, Sai Sundeep Kollala, Camila Pacheco, Paul M Grandgenett, Fang Yu, Vikas Kumar, Audrey J Lazenby, Adrian R Black, Susanna Ulhannan, Ajay Jain, Barish H Edil, David L Klinkebiel, Robert Powers, Amarnath Natarajan, Michael A Hollingsworth, Kamiya Mehla, Quan Ly, Sarika Chaudhary, Rosa F Hwang, Kathryn E Wellen, Pankaj K Singh.

The ability of tumour cells to thrive in harsh microenvironments depends on the utilization of nutrients available in the milieu. Here we show that pancreatic cancer-associated fibroblasts (CAFs) regulate tumour cell metabolism through the secretion of acetate, which can be blocked by silencing ATP citrate lyase (ACLY) in CAFs. We further show that acetyl-CoA synthetase short-chain family member 2 (ACSS2) channels the exogenous acetate to regulate the dynamic cancer epigenome and transcriptome, thereby facilitating cancer cell survival in an acidic microenvironment. Comparative H3K27ac ChIP-seq and RNA-seq analyses revealed alterations in polyamine homeostasis through regulation of SAT1 gene expression and enrichment of the SP1-responsive signature. We identified acetate/ACSS2-mediated acetylation of SP1 at the lysine 19 residue that increased SP1 protein stability and transcriptional activity. Genetic or pharmacologic inhibition of the ACSS2-SP1-SAT1 axis diminished the tumour burden in mouse models. These results reveal that the metabolic flexibility imparted by the stroma-derived acetate enabled cancer cell survival under acidosis via the ACSS2-SP1-SAT1 axis.

DOI: https://doi.org/10.1038/s41556-024-01372-4
Nat Commun. 2024 Feb 26. 15(1): 1721

Quiescence enables unrestricted cell fate in naive embryonic stem cells.

Le Tran Phuc Khoa, Wentao Yang, Mengrou Shan, Li Zhang, Fengbiao Mao, Bo Zhou, Qiang Li, Rebecca Malcore, Clair Harris, Lili Zhao, Rajesh Rao, Shigeki Iwase, Sundeep Kalantry, Stephanie L Bielas, Costas A Lyssiotis, Yali Dou.

Quiescence in stem cells is traditionally considered as a state of inactive dormancy or with poised potential. Naive mouse embryonic stem cells (ESCs) can enter quiescence spontaneously or upon inhibition of MYC or fatty acid oxidation, mimicking embryonic diapause in vivo. The molecular underpinning and developmental potential of quiescent ESCs (qESCs) are relatively unexplored. Here we show that qESCs possess an expanded or unrestricted cell fate, capable of generating both embryonic and extraembryonic cell types (e.g., trophoblast stem cells). These cells have a divergent metabolic landscape comparing to the cycling ESCs, with a notable decrease of the one-carbon metabolite S-adenosylmethionine. The metabolic changes are accompanied by a global reduction of H3K27me3, an increase of chromatin accessibility, as well as the de-repression of endogenous retrovirus MERVL and trophoblast master regulators. Depletion of methionine adenosyltransferase Mat2a or deletion of Eed in the polycomb repressive complex 2 results in removal of the developmental constraints towards the extraembryonic lineages. Our findings suggest that quiescent ESCs are not dormant but rather undergo an active transition towards an unrestricted cell fate.

DOI: https://doi.org/10.1038/s41467-024-46121-1
iScience. 2024 Mar 15. 27(3): 109189

Chemical inhibition of phosphatidylcholine biogenesis reveals its role in mitochondrial division.

Hiroya Shiino, Shinya Tashiro, Michiko Hashimoto, Yuki Sakata, Takamitsu Hosoya, Toshiya Endo, Hirotatsu Kojima, Yasushi Tamura.

  Phospholipids are major components of biological membranes and play structural and regulatory roles in various biological processes. To determine the biological significance of phospholipids, the use of chemical inhibitors of phospholipid metabolism offers an effective approach; however, the availability of such compounds is limited. In this study, we performed a chemical-genetic screening using yeast and identified small molecules capable of inhibiting phosphatidylcholine (PC) biogenesis, which we designated PC inhibitors 1, 2, 3, and 4 (PCiB-1, 2, 3, and 4). Biochemical analyses indicated that PCiB-2, 3, and 4 inhibited the phosphatidylethanolamine (PE) methyltransferase activity of Cho2, whereas PCiB-1 may inhibit PE transport from mitochondria to the endoplasmic reticulum (ER). Interestingly, we found that PCiB treatment resulted in mitochondrial fragmentation, which was suppressed by expression of a dominant-negative mutant of the mitochondrial division factor Dnm1. These results provide evidence that normal PC biogenesis is important for the regulation of mitochondrial division.

Keywords:  Biochemistry; Biological sciences; Cell biology

DOI:  https://doi.org/10.1016/j.isci.2024.109189
ACS Appl Mater Interfaces. 2024 Feb 27.

Screening of CPT1A-Targeting Lipid Metabolism Modulators Using Mitochondrial Membrane Chromatography.

Wu Su, Fanding Xu, Jinjin Zhong, Ranrui Hu, Lizhuo Wang, Hua Li, Zhiwei Yang, Shuai Ge, Huaizhen He, Shengli Han, Xiuying Xie, Hui Guo, Langchong He, Jiankang Liu, Tao Yi, Yu Kong, Jiangang Long.

  Carnitine palmitoyltransferase 1A (CPT1A), which resides on the mitochondrial outer membrane, serves as the rate-limiting enzyme of fatty acid β-oxidation. Identifying the compounds targeting CPT1A warrants a promising candidate for modulating lipid metabolism. In this study, we developed a CPT1A-overexpressed mitochondrial membrane chromatography (MMC) to screen the compounds with affinity for CPT1A. Cells overexpressing CPT1A were cultured, and subsequently, their mitochondrial membrane was isolated and immobilized on amino-silica gel cross-linked by glutaraldehyde. After packing the mitochondrial membrane column, retention components of MMC were performed with LC/MS, whose analytic peaks provided structural information on compounds that might interact with mitochondrial membrane proteins. With the newly developed MMC-LC/MS approach, several Chinese traditional medicine extracts, such as Scutellariae Radix and Polygoni Cuspidati Rhizoma et Radix (PCRR), were analyzed. Five noteworthy compounds, baicalin, baicalein, wogonoside, wogonin, and resveratrol, were identified as enhancers of CPT1A enzyme activity, with resveratrol being a new agonist for CPT1A. The study suggests that MMC serves as a reliable screening system for efficiently identifying modulators targeting CPT1A from complex extracts.

Keywords:  CPT1A; Chinese traditional medicine; lipid metabolism; mitochondrial membrane chromatography; mitochondrion-target molecule screening

DOI:  https://doi.org/10.1021/acsami.3c18102
Mol Ther Nucleic Acids. 2024 Mar 12. 35(1): 102132

mitoTALEN reduces the mutant mtDNA load in neurons.

Sandra R Bacman, Jose Domingo Barrera-Paez, Milena Pinto, Derek Van Booven, James B Stewart, Anthony J Griswold, Carlos T Moraes.

  Mutations within mtDNA frequently give rise to severe encephalopathies. Given that a majority of these mtDNA defects exist in a heteroplasmic state, we harnessed the precision of mitochondrial-targeted TALEN (mitoTALEN) to selectively eliminate mutant mtDNA within the CNS of a murine model harboring a heteroplasmic mutation in the mitochondrial tRNA alanine gene (m.5024C>T). This targeted approach was accomplished by the use of AAV-PHP.eB and a neuron-specific synapsin promoter for effective neuronal delivery and expression of mitoTALEN. We found that most CNS regions were effectively transduced and showed a significant reduction in mutant mtDNA. This reduction was accompanied by an increase in mitochondrial tRNA alanine levels, which are drastically reduced by the m.5024C>T mutation. These results showed that mitochondrial-targeted gene editing can be effective in reducing CNS-mutant mtDNA in vivo, paving the way for clinical trials in patients with mitochondrial encephalopathies.

Keywords:  AAV-PHPeB; CNS; MT: RNA/DNA editing; TALEN; gene therapy; heteroplasmy; mitochondria

DOI:  https://doi.org/10.1016/j.omtn.2024.102132
Eur J Med Chem. 2024 Feb 17. pii: S0223-5234(24)00135-1. [Epub ahead of print]268 116255

Novel sulfonamide-indolinone hybrids targeting mitochondrial respiration of breast cancer cells.

Sama W A Helmy, Amal Kamal Abdel-Aziz, Eman M E Dokla, Tarek E Ahmed, Yasmin Hatem, Engy A Abdel Rahman, Marwa Sharaky, Mai I Shahin, Eman Z Elrazaz, Rabah A T Serya, Maged Henary, Sameh S Ali, Dalal A Abou El Ella.

  Breast cancer (BC) still poses a threat worldwide which demands continuous efforts to present safer and efficacious treatment options via targeted therapy. Beside kinases' aberrations as Aurora B kinase which controls cell division, BC adopts distinct metabolic profiles to meet its high energy demands. Accordingly, targeting both aurora B kinase and/or metabolic vulnerability presents a promising approach to tackle BC. Based on a previously reported indolinone-based Aurora B kinase inhibitor (III), and guided by structural modification and SAR investigation, we initially synthesized 11 sulfonamide-indolinone hybrids (5a-k), which showed differential antiproliferative activities against the NCI-60 cell line panel with BC cells displaying preferential sensitivity. Nonetheless, modest activity against Aurora B kinase (18-49% inhibition) was noted at 100 nM. Screening of a representative derivative (5d) against 17 kinases, which are overexpressed in BC, failed to show significant activity at 1 μM concentration, suggesting that kinase inhibitory activity only played a partial role in targeting BC. Bioinformatic analyses of genome-wide transcriptomics (RNA-sequencing), metabolomics, and CRISPR loss-of-function screens datasets suggested that indolinone-completely responsive BC cell lines (MCF7, MDA-MB-468, and T-47D) were more dependent on mitochondrial oxidative phosphorylation (OXPHOS) compared to partially responsive BC cell lines (MDA-MB-231, BT-549, and HS 578 T). An optimized derivative, TC11, obtained by molecular hybridization of 5d with sunitinib polar tail, manifested superior antiproliferative activity and was used for further investigations. Indeed, TC11 significantly reduced/impaired the mitochondrial respiration, as well as mitochondria-dependent ROS production of MCF7 cells. Furthermore, TC11 induced G0/G1 cell cycle arrest and apoptosis of MCF7 BC cells. Notably, anticancer doses of TC11 did not elicit cytotoxic effects on normal cardiomyoblasts and hepatocytes. Altogether, these findings emphasize the therapeutic potential of targeting the metabolic vulnerability of OXPHOS-dependent BC cells using TC11 and its related sulfonamide-indolinone hybrids. Further investigation is warranted to identify their precise/exact molecular target.

Keywords:  Aurora B; Bioinformatics; Breast cancer; Indolinone hybrids; Mitochondrial OXPHOS; NCI-60 cell lines

DOI:  https://doi.org/10.1016/j.ejmech.2024.116255
Biol Direct. 2024 02 26. 19(1): 17

Comprehensive analysis of mitochondria-related genes indicates that PPP2R2B is a novel biomarker and promotes the progression of bladder cancer via Wnt signaling pathway.

Du Shen, Shaosan Kang.

  Bladder cancer (BC) is the fourth and tenth most common malignancy in men and women worldwide, respectively. The complexity of the molecular biological mechanism behind BC is a major contributor to the lack of effective treatment management of the disease. The development and genesis of BC are influenced by mitochondrial retrograde control and mitochondria-nuclear cross-talk. However, the role of mitochondrial-related genes in BC remains unclear. In this study, we analyzed TCGA datasets and identified 752 DE-MRGs in BC samples, including 313 down-regulated MRGs and 439 up-regulated MRGs. Then, the results of machine-learning screened four critical diagnostic genes, including GLRX2, NMT1, PPP2R2B and TRAF3IP3. Moreover, we analyzed their prognostic value and confirmed that only PPP2R2B was associated with clinical prognosis of BC patients and Cox regression assays validated that PPP2R2B expression was a distinct predictor of overall survival in BC patients. Them, we performed RT-PCR and found that PPP2R2B expression was distinctly decreased in BC specimens and cell lines. Functional experiments revealed that overexpression of PPP2R2B distinctly suppressed the proliferation, migration and invasion of BC cells via Wnt signaling pathway. In summary, these research findings offer potential molecular markers for the diagnosis and prognosis of BC, with the discovery of PPP2R2B particularly holding significant biological and clinical significance. This study provides valuable clues for future in-depth investigations into the molecular mechanisms of BC, as well as the development of new diagnostic markers and therapeutic targets.

Keywords:  Biomarker; Bladder cancer; Metastasis; Mitochondrial-related genes; PPP2R2B; Wnt signaling pathway

DOI:  https://doi.org/10.1186/s13062-024-00461-6
Nat Commun. 2024 Feb 28. 15(1): 1799

A spatial map of hepatic mitochondria uncovers functional heterogeneity shaped by nutrient-sensing signaling.

Sun Woo Sophie Kang, Rory P Cunningham, Colin B Miller, Lauryn A Brown, Constance M Cultraro, Adam Harned, Kedar Narayan, Jonathan Hernandez, Lisa M Jenkins, Alexei Lobanov, Maggie Cam, Natalie Porat-Shliom.

In the liver, mitochondria are exposed to different concentrations of nutrients due to their spatial positioning across the periportal and pericentral axis. How the mitochondria sense and integrate these signals to respond and maintain homeostasis is not known. Here, we combine intravital microscopy, spatial proteomics, and functional assessment to investigate mitochondrial heterogeneity in the context of liver zonation. We find that periportal and pericentral mitochondria are morphologically and functionally distinct; beta-oxidation is elevated in periportal regions, while lipid synthesis is predominant in the pericentral mitochondria. In addition, comparative phosphoproteomics reveals spatially distinct patterns of mitochondrial composition and potential regulation via phosphorylation. Acute pharmacological modulation of nutrient sensing through AMPK and mTOR shifts mitochondrial phenotypes in the periportal and pericentral regions, linking nutrient gradients across the lobule and mitochondrial heterogeneity. This study highlights the role of protein phosphorylation in mitochondrial structure, function, and overall homeostasis in hepatic metabolic zonation. These findings have important implications for liver physiology and disease.

DOI: https://doi.org/10.1038/s41467-024-45751-9