bims-celmim 2024-12-15 papers

bims-celmim

Biomed News

on Cellular and mitochondrial metabolism

Issue of 2024–12–15
twenty-six papers selected by
Marc Segarra Mondejar

Cell-specific oxidative metabolism of the renal cortex.
Synergistic label-free fluorescence imaging and miRNA studies reveal dynamic human neuron-glial metabolic interactions following injury.
Live cell imaging of lipid droplets: fluorescent chalcones as probes for lipophagy and lipid-mitochondria interactions.
Glutamine: A key player in human metabolism as revealed by hyperpolarized magnetic resonance.
Metabolic reprogramming, sensing, and cancer therapy.
Dual inhibition of oxidative phosphorylation and glycolysis exerts a synergistic antitumor effect on colorectal and gastric cancer by creating energy depletion and preventing metabolic switch.
Conjugated fatty acids drive ferroptosis through chaperone-mediated autophagic degradation of GPX4 by targeting mitochondria.
The adenine nucleotide translocase family underlies cardiac ischemia-reperfusion injury through the mitochondrial permeability pore independently of cyclophilin D.
Role of AMPK and Sirtuins in Aging Heart: Basic and Translational Aspects.
Mitochondrial fission is required for thermogenesis in brown adipose tissue.
Mitochondrial respiratory capacity in kidney podocytes is high, age-dependent, and sexually dimorphic.
PFKFB3 protein in adipose tissue contributes to whole body glucose homeostasis.
Intracellular endothelial cell metabolism in vascular function and dysfunction.
Cu in cancer metabolism.
Crosstalk between metabolic and epigenetic modifications during cell carcinogenesis.
Carnitine palmitoyltransferase 1 facilitates fatty acid oxidation in a non-cell-autonomous manner.
Lactate dehydrogenase B noncanonically promotes ferroptosis defense in KRAS-driven lung cancer.
SIRT5 mediated succinylation of SUCLA2 regulates TCA cycle dysfunction and mitochondrial damage in pancreatic acinar cells in acute pancreatitis.
Reactive oxygen species control protein degradation at the mitochondrial import gate.
Phages gain the upper hand in the metabolic arms race for NAD.
SPTLC3 regulates plasma membrane sphingolipid composition to facilitate hepatic gluconeogenesis.
Gold Nanoparticle Detection with Two-Photon Excitation Fluorescence Lifetime Imaging of NAD(P)H in Cancer Cells: An Analytical Approach to Separate Nanoparticle and NAD(P)H Signals.
The gas|liquid interface eclipses the liquid|liquid interface for glucose oxidase rate acceleration in microdroplets.
Emerging roles of hydrogen sulfide-metabolizing enzymes in cancer.
Electrocalcium coupling in brain capillaries: Rapidly traveling electrical signals ignite local calcium signals.
Scaffold-free development of multicellular tumor spheroids with spatial characterization of structure and metabolic radial profiles.

bioRxiv. 2024 Nov 25. pii: 2024.11.24.622516. [Epub ahead of print]

Cell-specific oxidative metabolism of the renal cortex.

Kyle Feola, Andrea H Venable, Tatyana Broomfield, Claire B Llamas, Prashant Mishra, Sarah C Huen.

The metabolic health of the kidney is a primary determinant of the risk of progressive kidney disease. Our understanding of the metabolic processes that fuel kidney functions is limited by the kidney's structural and functional heterogeneity. As the kidney contains many different cell types, we hypothesize that intra-renal mitochondrial heterogeneity contributes to cell-specific metabolism. To interrogate this, we utilized a recently developed mitochondrial tagging technique to isolate kidney cell-type specific mitochondria. Here, we investigate mitochondrial functional capacities and the metabolomes of the early and late proximal tubule (PT) and the distal convoluted tubule (DCT). The conditional MITO-Tag allele was combined with Slc34a1-CreERT2 , Ggt1-Cre , or Pvalb-Cre alleles to generate mouse models capable of cell-specific isolation of hemagglutinin (HA)-tagged mitochondria from the early PT, late PT, or the DCT, respectively. Functional assays measuring mitochondrial respiratory and fatty acid oxidation (FAO) capacities and metabolomics were performed on anti-HA immunoprecipitated mitochondria from kidneys of ad libitum fed and 24-hour fasted male mice. The renal MITO-Tag models targeting the early PT, late PT, and DCT revealed differential mitochondrial respiratory and FAO capacities which dynamically changed during fasting conditions. Changes with mitochondrial metabolomes induced by fasting suggest that the late PT significantly increases FAO during fasting. The renal MITO-Tag model captured differential mitochondrial metabolism and functional capacities across the early PT, late PT, and DCT at baseline and in response to fasting.
Translational Statement: While the renal cortex is often considered a single metabolic compartment, we discovered significant diversity of mitochondrial metabolomes and functional capacities across the proximal tubule and the distal convoluted tubule. As mitochondrial dysfunction is a major biochemical pathway related to kidney disease progression, understanding the differences in mitochondrial metabolism across distinct kidney cell populations is thus critical in the development of effective and targeted therapeutic therapies for acute and chronic kidney disease.

DOI: https://doi.org/10.1101/2024.11.24.622516
Sci Adv. 2024 Dec 13. 10(50): eadp1980

Synergistic label-free fluorescence imaging and miRNA studies reveal dynamic human neuron-glial metabolic interactions following injury.

Yang Zhang, Maria Savvidou, Volha Liaudanskaya, Pramesh Singh, Yuhang Fu, Amreen Nasreen, Marly Coe, Marilyn Kelly, Dustin Snapper, Chelsea Wagner, Jessica Gill, Aviva Symes, Abani Patra, David L Kaplan, Afshin Beheshti, Irene Georgakoudi.

Neuron-glial cell interactions following traumatic brain injury (TBI) determine the propagation of damage and long-term neurodegeneration. Spatiotemporally heterogeneous cytosolic and mitochondrial metabolic pathways are involved, leading to challenges in developing effective diagnostics and treatments. An engineered three-dimensional brain tissue model comprising human neurons, astrocytes, and microglia is used in combination with label-free, two-photon imaging and microRNA studies to characterize metabolic interactions between glial and neuronal cells over 72 hours following impact injury. We interpret multiparametric, quantitative, optical metabolic assessments in the context of microRNA gene set analysis and identify distinct metabolic changes in neurons and glial cells. Glycolysis, nicotinamide adenine dinucleotide phosphate (reduced form) and glutathione synthesis, fatty acid synthesis, and oxidation are mobilized within glial cells to mitigate the impacts of initial enhancements in oxidative phosphorylation and fatty acid oxidation within neurons, which lack robust antioxidant defenses. This platform enables enhanced understanding of mechanisms that may be targeted to improve TBI diagnosis and treatment.

DOI: https://doi.org/10.1126/sciadv.adp1980
J Mater Chem B. 2024 Dec 11.

Live cell imaging of lipid droplets: fluorescent chalcones as probes for lipophagy and lipid-mitochondria interactions.

Mohini Ghorpade, Deeksha Rajput, Paramasivam Mahalingam, Sriram Kanvah.

Lipid droplets are crucial organelles involved in cellular energy storage and metabolism, which is key in maintaining energy homeostasis through lipophagy. In this work, we successfully synthesized donor-acceptor chalcone derivatives (M1-M3) with improved photophysical characteristics, such as significant Stokes shifts and strong emission features. DFT and TDDFT calculations have been employed to evaluate the structure-property relationship of the chalcone derivatives. The molecules show excellent selectivity in staining lipid droplets in COS-7 cells and other cell lines. The molecule M1 was also further utilized to monitor verapamil-induced lipophagy. Using M1, we also demonstrate the link between lipid droplets and mitochondria during stress, emphasizing the significance of lipophagy in cellular energy balance and metabolism. These results not only shed light on the lipid metabolism but also have profound implications for researching and potentially treating metabolic diseases, underscoring the importance of our work in the field.

DOI: https://doi.org/10.1039/d4tb01871k
Prog Nucl Magn Reson Spectrosc. 2024 Nov-Dec;144-145:pii: S0079-6565(24)00012-8. [Epub ahead of print]144-145 15-39

Glutamine: A key player in human metabolism as revealed by hyperpolarized magnetic resonance.

Karen Dos Santos, Gildas Bertho, Mathieu Baudin, Nicolas Giraud.

In recent years, there has been remarkable progress in the field of dissolution dynamic nuclear polarization (D-DNP). This method has shown significant potential for enhancing nuclear polarization by over 10,000 times, resulting in a substantial increase in sensitivity. The unprecedented signal enhancements achieved with D-DNP have opened new possibilities for in vitro analysis. This method enables the monitoring of structural and enzymatic kinetics with excellent time resolution at low concentrations. Furthermore, these advances can be straightforwardly translated to in vivo magnetic resonance imaging and magnetic resonance spectroscopy (MRI and MRS) experiments. D-DNP studies have used a range of 13C labeled molecules to gain deeper insights into the cellular metabolic pathways and disease hallmarks. Over the last 15 years, D-DNP has been used to analyze glutamine, a key player in the cellular metabolism, involved in many diseases including cancer. Glutamine is the most abundant amino acid in blood plasma and the major carrier of nitrogen, and it is converted to glutamate inside the cell, where the latter is the most abundant amino acid. It has been shown that increased glutamine consumption by cells is a hallmark of tumor cancer metabolism. In this review, we first highlight the significance of glutamine in metabolism, providing an in-depth description of its use at the cellular level as well as its specific roles in various organs. Next, we present a comprehensive overview of the principles of D-DNP. Finally, we review the state of the art in D-DNP glutamine analysis and its application in oncology, neurology, and perfusion marker studies.

DOI: https://doi.org/10.1016/j.pnmrs.2024.05.003
Cell Rep. 2024 Dec 12. pii: S2211-1247(24)01415-3. [Epub ahead of print]43(12): 115064

Metabolic reprogramming, sensing, and cancer therapy.

Youxiang Mao, Ziyan Xia, Wenjun Xia, Peng Jiang.

  The metabolic reprogramming of tumor cells is a crucial strategy for their survival and proliferation, involving tissue- and condition-dependent remodeling of certain metabolic pathways. While it has become increasingly clear that tumor cells integrate extracellular and intracellular signals to adapt and proliferate, nutrient and metabolite sensing also exert direct or indirect influences, although the underlying mechanisms remain incompletely understood. Furthermore, metabolic changes not only support the rapid growth and dissemination of tumor cells but also promote immune evasion by metabolically "educating" immune cells in the tumor microenvironment (TME). Recent studies have highlighted the profound impact of metabolic reprogramming on the TME and the potential of targeting metabolic pathways as a therapeutic strategy, with several enzyme inhibitors showing promising results in clinical trials. Thus, understanding how tumor cells alter their metabolic pathways and metabolically remodel the TME to support their survival and proliferation may offer new strategies for metabolic therapy and immunotherapy.

Keywords:  CP: Metabolism; immunometabolism; metabolic reprogramming; metabolite sensing; tumor metabolism; tumor therapy

DOI:  https://doi.org/10.1016/j.celrep.2024.115064
PLoS One. 2024 ;19(12): e0309700

Dual inhibition of oxidative phosphorylation and glycolysis exerts a synergistic antitumor effect on colorectal and gastric cancer by creating energy depletion and preventing metabolic switch.

Yuki Aisu, Nobu Oshima, Fuminori Hyodo, Abdelazim Elsayed Elhelaly, Akihiko Masuo, Tomoaki Okada, Shigeo Hisamori, Shigeru Tsunoda, Koya Hida, Tomonori Morimoto, Hiroyuki Miyoshi, Makoto M Taketo, Masayuki Matsuo, Leonard M Neckers, Yoshiharu Sakai, Kazutaka Obama.

Pyruvate is situated at the intersection of oxidative phosphorylation (OXPHOS) and glycolysis, which are the primary energy-producing pathways in cells. Cancer therapies targeting these pathways have been previously documented, indicating that inhibiting one pathway may lead to functional compensation by the other, resulting in an insufficient antitumor effect. Thus, effective cancer treatment necessitates concurrent and comprehensive suppression of both. However, whether a metabolic switch between the metabolic pathways occurs in colorectal and gastric cancer cells and whether blocking it by inhibiting both pathways has an antitumor effect remain to be determined. In the present study, we used two small molecules, namely OXPHOS and glycolysis inhibitors, to target pyruvate metabolic pathways as a cancer treatment in these cancer cells. OXPHOS and glycolysis inhibition each augmented the other metabolic pathway in vitro and in vivo. OXPHOS inhibition alone enhanced glycolysis and showed antitumor effects on colorectal and gastric cancer cells in vitro and in vivo. Moreover, glycolysis inhibition in addition to OXPHOS inhibition blocked the metabolic switch from OXPHOS to glycolysis, causing an energy depletion and deterioration of the tumor microenvironment that synergistically enhanced the antitumor effect of OXPHOS inhibitors. In addition, using hyperpolarized 13C-magnetic resonance spectroscopic imaging (HP-MRSI), which enables real-time and in vivo monitoring of molecules containing 13C, we visualized how the inhibitors shifted the flux of pyruvate and how this dual inhibition in colorectal and gastric cancer mouse models altered the two pathways. Integrating dual inhibition of OXPHOS and glycolysis with HP-MRSI, this therapeutic model shows promise as a future "cancer theranostics" treatment option.

DOI: https://doi.org/10.1371/journal.pone.0309700
Cell Death Dis. 2024 Dec 06. 15(12): 884

Conjugated fatty acids drive ferroptosis through chaperone-mediated autophagic degradation of GPX4 by targeting mitochondria.

Yusuke Hirata, Yuto Yamada, Soma Taguchi, Ryota Kojima, Haruka Masumoto, Shinnosuke Kimura, Takuya Niijima, Takashi Toyama, Ryoji Kise, Emiko Sato, Yasunori Uchida, Junya Ito, Kiyotaka Nakagawa, Tomohiko Taguchi, Asuka Inoue, Yoshiro Saito, Takuya Noguchi, Atsushi Matsuzawa.

Conjugated fatty acids (CFAs) have been known for their anti-tumor activity. However, the mechanism of action remains unclear. Here, we identify CFAs as inducers of glutathione peroxidase 4 (GPX4) degradation through chaperone-mediated autophagy (CMA). CFAs, such as (10E,12Z)-octadecadienoic acid and α-eleostearic acid (ESA), induced GPX4 degradation, generation of mitochondrial reactive oxygen species (ROS) and lipid peroxides, and ultimately ferroptosis in cancer cell lines, including HT1080 and A549 cells, which were suppressed by either pharmacological blockade of CMA or genetic deletion of LAMP2A, a crucial molecule for CMA. Mitochondrial ROS were sufficient and necessary for CMA-dependent GPX4 degradation. Oral administration of an ESA-rich oil attenuated xenograft tumor growth of wild-type, but not that of LAMP2A-deficient HT1080 cells, accompanied by increased lipid peroxidation, GPX4 degradation and cell death. Our study establishes mitochondria as the key target of CFAs to trigger lipid peroxidation and GPX4 degradation, providing insight into ferroptosis-based cancer therapy.

DOI: https://doi.org/10.1038/s41419-024-07237-w
Sci Adv. 2024 Dec 13. 10(50): eadp7444

The adenine nucleotide translocase family underlies cardiac ischemia-reperfusion injury through the mitochondrial permeability pore independently of cyclophilin D.

Pooja Patel, Arielys Mendoza, Daniel Ramirez, Dexter Robichaux, Jeffery D Molkentin, Jason Karch.

The mitochondrial permeability transition pore (mPTP) is implicated in cardiac ischemia-reperfusion (I/R) injury. During I/R, elevated mitochondrial Ca2+ triggers mPTP opening, leading to necrotic cell death. Although nonessential regulators of this pore are characterized, the molecular identity of the pore-forming component remains elusive. Two of these genetically verified regulators are cyclophilin D (CypD) and the adenine nucleotide translocase (ANT) family. We investigated the ANT/CypD relationship in mPTP dynamics and I/R injury. Despite lacking all ANT isoforms, Ca2+-dependent mPTP opening persisted in cardiac mitochondria but was desensitized. This desensitization conferred resistance to I/R injury in ANT-deficient mice. CypD is hypothesized to trigger mPTP opening through isomerization of ANTs at proline-62. To test this, we generated mice that expressed a P62A mutated version of ANT1. These mice showed similar mPTP dynamics and I/R sensitivity as the wild type, indicating that P62 is dispensable for CypD regulation. Together, these data indicate that the ANT family contributes to mPTP opening independently of CypD.

DOI: https://doi.org/10.1126/sciadv.adp7444
Aging Dis. 2024 Dec 03.

Role of AMPK and Sirtuins in Aging Heart: Basic and Translational Aspects.

Maria Luisa Barcena, Muhammad Aslam, Kristina Norman, Christiane Ott, Yury Ladilov.

Aging is a key risk factor for numerous diseases, including cardiac diseases. High energy demands of the heart require precise cellular energy sensing to prevent metabolic stress. AMPK and sirtuins are key intracellular metabolic sensors regulating numerous cell functions, like mitochondrial function and biogenesis, autophagy, and redox balance. However, their function is impaired during the aging process leading to mitochondrial dysfunction, oxidative stress, and inflammation culminating in cardiovascular diseases. The underlying molecular mechanisms leading to dysfunction of metabolic sensing in the aging heart are complex and comprise both intracellular and systemic age-related alterations. In this study, we overview the current knowledge on the impact of aging on cardiac metabolic sensing, with a focus on AMPK and sirtuins, while mTOR pathway was only marginally considered. A particular focus was given to systemic factors, e.g., inflammation, vascular diseases, and microbiome.

DOI: https://doi.org/10.14336/AD.2024.1216
PLoS One. 2024 ;19(12): e0312352

Mitochondrial fission is required for thermogenesis in brown adipose tissue.

Yuta Ibayashi, Nao Hasuzawa, Seiji Nomura, Masaharu Kabashima, Ayako Nagayama, Shimpei Iwata, Miyuki Kitamura, Kenji Ashida, Yoshinori Moriyama, Ken Yamamoto, Masatoshi Nomura, Lixiang Wang.

Brown adipose tissue (BAT) thermogenesis is pivotal for maintaining body temperature and energy balance. Mitochondrial morphology is dynamically controlled by a balance between fusion and fission, which is crucial for cell differentiation, response to metabolic insults, and heat production. Dynamin-related protein 1 (Drp1) is a key regulator of mitochondrial fission. This study investigates the role of Drp1 in BAT development and thermogenesis by generating Drp1-deficient mice. These mice were created by crossing Drp1 floxed mice with fatty acid-binding protein 4-Cre (aP2-Cre) transgenic mice, resulting in aP2-Cre+/-Drp1flox/flox (aP2-Drp1f/f) mice. The aP2-Drp1f/f mice exhibited severe BAT and brain hypoplasia, with the majority dying within 48 hours postnatally, highlighting Drp1's crucial role in neonatal survival. Impaired thermogenic responses were observed in aP2-Drp1f/f mice, characterized by significantly decreased expression of thermogenic and lipogenic genes in BAT. Ultrastructural analysis revealed disrupted mitochondrial morphology and reduced lipid droplet content in BAT. The few surviving adult aP2-Drp1f/f mice also showed impaired BAT and brain development, along with BAT thermogenesis dysfunction during cold exposure. Our findings underscore the essential role of Drp1-mediated mitochondrial fission in BAT thermogenesis and neonatal survival, providing insights into potential therapeutic approaches for metabolic disorders.

DOI: https://doi.org/10.1371/journal.pone.0312352
bioRxiv. 2024 Nov 26. pii: 2024.11.24.625104. [Epub ahead of print]

Mitochondrial respiratory capacity in kidney podocytes is high, age-dependent, and sexually dimorphic.

Matthew D Campbell, Monica Sanchez-Contreras, Britta D Sibley, Phoebe Keiser, Carla Ruiz Sanchez, Carolyn N Mann, David J Marcinek, Behzad Najafian, Mariya T Sweetwyne.

Whether and how podocytes depend on mitochondria across their long post-mitotic lifespan is yet unclear. With limited cell numbers and broad kidney distribution, isolation of podocyte mitochondria typically requires first isolating podocytes themselves. Disassociation of podocytes from their basement membrane, however, recapitulates an injured state that may stress mitochondria. To address this, we crossed floxed hemagglutinin (HA) -mitochondria tagged (MITO-Tag) mice with those expressing Cre in either podocytes (NPHS2) or distal tubule and collecting duct (CDH16), thus allowing for rapid, kidney cell-specific, isolation of mitochondria via immunoprecipitation. Mitochondrial respiration in fresh isolates from young (4-7 mo) and aged (22-26 mo) mice of both sexes demonstrated several previously unreported significant differences between podocyte and tubule mitochondria. First, although podocytes contain fewer mitochondria than do tubule cells, mitochondria isolated from podocytes averaged twice the respiratory capacity of tubule mitochondria when normalized to mitochondrial content by citrate synthase (CS) levels. Second, age-related decline in respiration was detected only in podocyte mitochondria and only in aged male mice. Finally, disassociating podocytes for cell culture initiates functional decline in mitochondria as those from cultured primary podocytes have half the respiratory capacity, but twice the hydrogen peroxide production of podocyte mitochondria isolated directly from fresh kidneys. Thus, podocytes maintain sexually dimorphic mitochondria with greater oxidative phosphorylation capacity than mitochondria-dependent tubules per organelle. Previous studies may not have detected these differences due to reliance on podocyte cell culture conditions, which results in artifactual suppression of mitochondrial function.

DOI: https://doi.org/10.1101/2024.11.24.625104
FASEB J. 2024 Dec 15. 38(23): e70254

PFKFB3 protein in adipose tissue contributes to whole body glucose homeostasis.

Beth A Griesel, Ann Louise Olson.

  Age-dependent changes in adipose tissue are thought to play a role in development of insulin resistance. A major age-dependent change in adipose tissue is the downregulation of key proteins involved in carbohydrate metabolism. In the current study, we investigate the role of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) a key governor of the rate of glycolysis in adipocytes via the synthesis of fructose-2,6-bisphosphate that was significantly downregulated in aged mice. We employed an adipocyte-specific PFKFB3 mouse line to investigate the role of PFKFB3 on adipocyte function. In both aged mice and PFKFB3-knockout mice, we observed an increase in O-glcNAcylated proteins consistent with a shift in glucose metabolism toward the hexosamine biosynthetic pathway. Under chow-fed conditions, PFKFB3 knockout resulted in significantly smaller adipocyte area, but no difference in total fat mass. While glucose tolerance was unchanged under chow conditions, when mice were challenged with a 4 weeks high-fat feeding, PFKFB3 deletion led to a greater decrease in glucose tolerance as well as a significant increase in macrophage infiltration. These results indicate that perturbation of the glycolytic pathway in adipose tissue has multiple effects of adipocyte biology and may play a significant role in metabolic changes associated with aging. Results of this student support the notion that changes in glucose metabolism in adipose tissue impact whole-body metabolism.

Keywords:  O‐glcNAcylation; PFKFB3; adipose; aging; glucose homeostasis

DOI:  https://doi.org/10.1096/fj.202402070R
Trends Endocrinol Metab. 2024 Dec 12. pii: S1043-2760(24)00296-0. [Epub ahead of print]

Intracellular endothelial cell metabolism in vascular function and dysfunction.

Kathryn M Citrin, Balkrishna Chaube, Carlos Fernández-Hernando, Yajaira Suárez.

  Endothelial cells (ECs) form the inner lining of blood vessels that is crucial for vascular function and homeostasis. They regulate vascular tone, oxidative stress, and permeability. Dysfunction leads to increased permeability, leukocyte adhesion, and thrombosis. ECs undergo metabolic changes in conditions such as wound healing, cancer, atherosclerosis, and diabetes, and can influence disease progression. We discuss recent research that has revealed diverse intracellular metabolic pathways in ECs that are tailored to their functional needs, including lipid handling, glycolysis, and fatty acid oxidation (FAO). Understanding EC metabolic signatures in health and disease will be crucial not only for basic biology but can also be exploited when designing new therapies to target EC-related functions in different vascular diseases.

Keywords:  angiogenesis; atherosclerosis; endometabolism; endothelial cell; lipid metabolism

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

Cu in cancer metabolism.

Zhe Wang.

DOI: https://doi.org/10.1038/s41556-024-01578-6
iScience. 2024 Dec 20. 27(12): 111359

Crosstalk between metabolic and epigenetic modifications during cell carcinogenesis.

Yue Gao, Siyu Zhang, Xianhong Zhang, Yitian Du, Ting Ni, Shuailin Hao.

  Genetic mutations arising from various internal and external factors drive cells to become cancerous. Cancerous cells undergo numerous changes, including metabolic reprogramming and epigenetic modifications, to support their abnormal proliferation. This metabolic reprogramming leads to the altered expression of many metabolic enzymes and the accumulation of metabolites. Recent studies have shown that these enzymes and metabolites can serve as substrates or cofactors for chromatin-modifying enzymes, thereby participating in epigenetic modifications and promoting carcinogenesis. Additionally, epigenetic modifications play a role in the metabolic reprogramming and immune evasion of cancer cells, influencing cancer progression. This review focuses on the origins of cancer, particularly the metabolic reprogramming of cancer cells and changes in epigenetic modifications. We discuss how metabolites in cancer cells contribute to epigenetic remodeling, including lactylation, acetylation, succinylation, and crotonylation. Finally, we review the impact of epigenetic modifications on tumor immunity and the latest advancements in cancer therapies targeting these modifications.

Keywords:  Epigenetics; Molecular genetics

DOI:  https://doi.org/10.1016/j.isci.2024.111359
Cell Rep. 2024 Dec 12. pii: S2211-1247(24)01357-3. [Epub ahead of print]43(12): 115006

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

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

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

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

DOI:  https://doi.org/10.1016/j.celrep.2024.115006
Cell Death Differ. 2024 Dec 07.

Lactate dehydrogenase B noncanonically promotes ferroptosis defense in KRAS-driven lung cancer.

Liang Zhao, Haibin Deng, Jingyi Zhang, Nicola Zamboni, Haitang Yang, Yanyun Gao, Zhang Yang, Duo Xu, Haiqing Zhong, Geert van Geest, Rémy Bruggmann, Qinghua Zhou, Ralph A Schmid, Thomas M Marti, Patrick Dorn, Ren-Wang Peng.

Ferroptosis is an oxidative, non-apoptotic cell death frequently inactivated in cancer, but the underlying mechanisms in oncogene-specific tumors remain poorly understood. Here, we discover that lactate dehydrogenase (LDH) B, but not the closely related LDHA, subunits of active LDH with a known function in glycolysis, noncanonically promotes ferroptosis defense in KRAS-driven lung cancer. Using murine models and human-derived tumor cell lines, we show that LDHB silencing impairs glutathione (GSH) levels and sensitizes cancer cells to blockade of either GSH biosynthesis or utilization by unleashing KRAS-specific, ferroptosis-catalyzed metabolic synthetic lethality, culminating in increased glutamine metabolism, oxidative phosphorylation (OXPHOS) and mitochondrial reactive oxygen species (mitoROS). We further show that LDHB suppression upregulates STAT1, a negative regulator of SLC7A11, thereby reducing SLC7A11-dependent GSH metabolism. Our study uncovers a previously undefined mechanism of ferroptosis resistance involving LDH isoenzymes and provides a novel rationale for exploiting oncogene-specific ferroptosis susceptibility to treat KRAS-driven lung cancer.

DOI: https://doi.org/10.1038/s41418-024-01427-x
Biochim Biophys Acta Mol Basis Dis. 2024 Dec 04. pii: S0925-4439(24)00607-0. [Epub ahead of print]1871(3): 167613

SIRT5 mediated succinylation of SUCLA2 regulates TCA cycle dysfunction and mitochondrial damage in pancreatic acinar cells in acute pancreatitis.

Wenbin Liu, Xiaofeng Wang, Dan Xu, Fangchen Gong, Lei Pei, Song Yang, Shanzhi Zhao, Xiangtao Zheng, Ranran Li, Zhitao Yang, Jian Fei, Enqiang Mao, Erzhen Chen, Ying Chen.

  Acute pancreatitis (AP) is a severe inflammatory disorder associated with metabolic reprogramming and mitochondrial dysfunction. This study investigated central carbon metabolism alterations in pancreatic acinar cells during AP, elucidated the molecular mechanisms of tricarboxylic acid (TCA) cycle disorders, and explored the role of protein hypersuccinylation in AP pathogenesis. Using in vitro and in vivo AP models, targeted metabolomics and bioinformatics analyses revealed TCA cycle dysregulation characterized by elevated succinyl-CoA and decreased succinate levels. Colorimetric assays, mass spectrometry, and site-directed mutagenesis demonstrated that SIRT5 downregulation led to SUCLA2 hypersuccinylation at K118, inhibiting succinyl-CoA synthetase activity and triggering a vicious cycle of succinyl-CoA accumulation and SUCLA2 succinylation. Adenovirus-mediated SIRT5 overexpression and SUCLA2 knockdown clarified the SIRT5-SUCLA2 pathway's role in regulating TCA cycle disorders. Protein succinylation levels positively correlated with pancreatic tissue damage and mitochondrial injury severity. Succinylome analysis identified cytochrome c1 (CYC1) as a key hypersuccinylated protein, and the SIRT5-SUCLA2 pathway regulated its succinylation level and electron transport chain complex III activity. Hypersuccinylation induced mitochondrial DNA release, activating the cGAS-STING pathway, contributing to multiple organ dysfunction syndrome. Modulating the SIRT5-SUCLA2 axis attenuated TCA cycle dysregulation, protein hypersuccinylation, mitochondrial damage, and inflammatory responses in AP. These findings reveal novel mechanisms linking the SIRT5-SUCLA2 axis, TCA cycle dysfunction, and protein hypersuccinylation in AP pathogenesis, providing potential therapeutic targets for AP treatment.

Keywords:  Acute pancreatitis; Inflammatory; Mitochondrial; Succinylation; TCA cycle

DOI:  https://doi.org/10.1016/j.bbadis.2024.167613
Mol Cell. 2024 Dec 05. pii: S1097-2765(24)00909-2. [Epub ahead of print]84(23): 4612-4628.e13

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

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

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

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

DOI:  https://doi.org/10.1016/j.molcel.2024.11.004
Mol Cell. 2024 Dec 05. pii: S1097-2765(24)00922-5. [Epub ahead of print]84(23): 4480-4482

Phages gain the upper hand in the metabolic arms race for NAD.

Nathan P Bullen, Aaron T Whiteley.

Bacteria often defend against phage infection by deploying NADase effectors to degrade cellular NAD+, thereby halting both bacterial growth and phage replication. In a recent article in Nature, Osterman et al.1 identify phage-encoded counterdefense pathways that reconstitute NAD+ during infection, enabling phages to combat multiple unrelated antiphage systems.

DOI: https://doi.org/10.1016/j.molcel.2024.11.017
Cell Rep. 2024 Dec 10. pii: S2211-1247(24)01405-0. [Epub ahead of print]43(12): 115054

SPTLC3 regulates plasma membrane sphingolipid composition to facilitate hepatic gluconeogenesis.

David Montefusco, Maryam Jamil, Daniel Canals, Siri Saligrama, Yang Yue, Jeremy Allegood, L Ashley Cowart.

  SPTLC3, an inducible subunit of the serine palmitoyltransferase (SPT) complex, causes production of alternative sphingoid bases, including a 16-carbon dihydrosphingosine, whose biological function is only beginning to emerge. High-fat feeding induced SPTLC3 in the liver, prompting us to produce a liver-specific knockout mouse line. Following high-fat feeding, knockout mice showed decreased fasting blood glucose, and knockout primary hepatocytes showed suppressed glucose production, a core function of hepatocytes. Stable isotope tracing revealed suppression of the gluconeogenic pathway, finding that SPTLC3 was required to maintain expression of key gluconeogenic genes via adenylate cyclase/cyclic AMP (cAMP)/cAMP response element binding protein (CREB) signaling. Additionally, by employing a combination of a recently developed lipidomics methodology, exogenous C14/C16 fatty acid treatment, and in situ adenylate cyclase activity, we implicated a functional interaction between sphingomyelin with a d16 backbone and adenylate cyclase at the plasma membrane. This work pinpoints a specific sphingolipid-protein functional interaction with broad implications for understanding sphingolipid signaling and metabolic disease.

Keywords:  CP: Metabolism; MAFLD; SPT; SPTLC3; adenylate cylcase; ceramide; cyclic-AMP; gluconeogenesis; metabolic disease; sphingolipid; sphingomyelin

DOI:  https://doi.org/10.1016/j.celrep.2024.115054
Anal Chem. 2024 Dec 12.

Gold Nanoparticle Detection with Two-Photon Excitation Fluorescence Lifetime Imaging of NAD(P)H in Cancer Cells: An Analytical Approach to Separate Nanoparticle and NAD(P)H Signals.

Mahshid Ghasemi, Amy Holmes, Tyron Turnbull, Ivan Kempson.

Gold nanoparticles (AuNPs) have shown promise for applications in the diagnosis and treatment of different diseases, including cancer. Understanding the effect of AuNPs on metabolic reprogramming in cancer cells at the single cell level is of high importance for improving the efficacy and safety. Fluorescence lifetime imaging microscopy (FLIM) of nicotinamide adenine dinucleotide (phosphate) hydrogen (NAD(P)H) as a main metabolic cofactor and an indicator of metabolic reprogramming in cancer cells enables real-time monitoring of cancer cell metabolism in response to different treatments, including AuNPs. However, NPs such as AuNPs can be a potential source of signals themselves, which provides opportunities to measure the NP internalization, but it is also important to minimize confounding effects on metabolic measurements. In this study, we detected inherent photoluminescence (PL) from the AuNPs in treated prostate cancer cells (PC-3 cell line) as well as in solution at the NAD(P)H emission wavelength. We developed an analysis approach to minimize the confounding effect of the AuNPs' PL on metabolic measurements. On the other hand, we assessed the reliability of the intracellular AuNPs' PL as an estimator of AuNP uptake. To assess if intracellular AuNPs' PL may be dependent on the exposed cell type, we performed NAD(P)H FLIM imaging of AuNP-exposed SKBR-3 breast cancer cells, where we observed a similar AuNP PL but at a much lower level compared to PC-3 cells. We proposed that this difference can be attributed to the different levels of AuNP uptake or varying intracellular microenvironments.

DOI: https://doi.org/10.1021/acs.analchem.4c04214
Proc Natl Acad Sci U S A. 2024 Dec 17. 121(51): e2416353121

The gas|liquid interface eclipses the liquid|liquid interface for glucose oxidase rate acceleration in microdroplets.

Lynn E Krushinski, Patrick J Herchenbach, Jeffrey E Dick.

  The curious chemistry observed in microdroplets has captivated chemists in recent years and has led to an investigation into their ability to drive seemingly impossible chemistries. One particularly interesting capability of these microdroplets is their ability to accelerate reactions by several orders of magnitude. While there have been many investigations into which reactions can be accelerated by confinement within microdroplets, no study has directly compared reaction acceleration at the liquid|liquid and gas|liquid interfaces. Here, we confine glucose oxidase, one of life's most important enzymes, to microdroplets and monitor the turnover rate of glucose by the electroactive cofactor, hexacyanoferrate (III). We use stochastic electrochemistry to monitor the collision of single femtoliter water droplets on an ultramicroelectrode. We also develop a measurement modality to robustly quantify reaction rates for femtoliter liquid aerosol droplets, where the majority of the interface is gas|liquid. We demonstrate that the gas|liquid interface accelerates enzyme turnover by over an order of magnitude over the liquid|liquid interface. This is the first apples-to-apples comparison of reaction acceleration at two distinct interfaces that indicates that the gas|liquid interface plays a central role in driving curious chemistry.

Keywords:  electrochemistry; enzyme; microdroplet

DOI:  https://doi.org/10.1073/pnas.2416353121
Redox Rep. 2024 Dec;29(1): 2437338

Emerging roles of hydrogen sulfide-metabolizing enzymes in cancer.

Alyaa Dawoud, Rana A Youness, Kareem Elsayed, Heba Nafae, Hoda Allam, Hager Adel Saad, Carole Bourquin, Csaba Szabo, Reham Abdel-Kader, Mohamed Z Gad.

  Gasotransmitters play crucial roles in regulating many physiological processes, including cell signaling, cellular proliferation, angiogenesis, mitochondrial function, antioxidant production, nervous system functions and immune responses. Hydrogen sulfide (H2S) is the most recently identified gasotransmitter, which is characterized by its biphasic behavior. At low concentrations, H2S promotes cellular bioenergetics, whereas at high concentrations, it can exert cytotoxic effects. Cystathionine β-synthetase (CBS), cystathionine-γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3-MST), and cysteinyl-tRNA synthetase 2 (CARS2) are pivotal players in H2S biosynthesis in mammalian cells and tissues. The focus of this review is the regulation of the various pathways involved in H2S metabolism in various forms of cancer. Key enzymes in this process include the sulfide oxidation unit (SOU), which includes sulfide:quinone oxidoreductase (SQOR), human ethylmalonic encephalopathy protein 1 (hETHE1), rhodanese, sulfite oxidase (SUOX/SO), and cytochrome c oxidase (CcO) enzymes. Furthermore, the potential role of H2S methylation processes mediated by thiol S-methyltransferase (TMT) and thioether S-methyltransferase (TEMT) is outlined in cancer biology, with potential opportunities for targeting them for clinical translation. In order to understand the role of H2S in oncogenesis and tumor progression, one must appreciate the intricate interplay between H2S-synthesizing and H2S-catabolizing enzymes.

Keywords:  H2S; cysteine aminotransferase (CAT); ethylmalonic encephalopathy protein 1 (ETHE1); metabolism; sulfide quinone oxidoreductase (SQOR); sulfite oxidase (SUOX)

DOI:  https://doi.org/10.1080/13510002.2024.2437338
Proc Natl Acad Sci U S A. 2024 Dec 17. 121(51): e2415047121

Electrocalcium coupling in brain capillaries: Rapidly traveling electrical signals ignite local calcium signals.

Amreen Mughal, Grant W Hennig, Thomas Heppner, Nikolaos M Tsoukias, David Hill-Eubanks, Mark T Nelson.

  The routing of blood flow throughout the brain vasculature is precisely controlled by mechanisms that serve to maintain a fine balance between local neuronal demands and vascular supply of nutrients. We recently identified two capillary endothelial cell (cEC)-based mechanisms that control cerebral blood flow in vivo: 1) electrical signaling, mediated by extracellular K+-dependent activation of strong inward rectifying K+ (Kir2.1) channels, which are steeply activated by hyperpolarization and thus are capable of cell-to-cell propagation, and 2) calcium (Ca2+) signaling, which reflects release of Ca2+ via the inositol 1,4,5-trisphosphate receptor (IP3R)-a target of Gq-protein-coupled receptor signaling. Notably, Ca2+ signals were restricted to the cell in which they were initiated. Unexpectedly, we found that these two mechanisms, which were presumed to operate in distinct spatiotemporal realms, are linked such that Kir2.1-dependent hyperpolarization induces increases in the electrical driving force for Ca2+ entry into cECs through resident TRPV4 channels. This process, termed electrocalcium (E-Ca) coupling, enhances IP3R-mediated Ca2+ release via a Ca2+-induced Ca2+-release mechanism, and allows focally induced hyperpolarization, including that initiated by ATP-dependent K+ (KATP) channels, to travel cell-to-cell via activation of Kir2.1 channels in adjacent cells, providing a mechanism for the "pseudopropagation" of Ca2+ signals. Computational modeling supported the basic features of E-Ca coupling and provided insight into the intracellular processes involved. Collectively, these data provide strong support for the concept of E-Ca coupling and provide a mechanism for the spatiotemporal integration of diverse signaling pathways in the control of cerebral blood flow.

Keywords:  blood flow; brain capillaries; calcium signaling; endothelial cells; potassium channels

DOI:  https://doi.org/10.1073/pnas.2415047121
In Vitro Model. 2024 ;3(2-3): 91-108

Scaffold-free development of multicellular tumor spheroids with spatial characterization of structure and metabolic radial profiles.

Shelby N Bess, Gaven K Smart, Matthew J Igoe, Timothy J Muldoon.

   Purpose: In vitro assays are essential for studying cellular biology, but traditional monolayer cultures fail to replicate the complex three-dimensional (3D) interactions of cells in living organisms. 3D culture systems offer a more accurate reflection of the cellular microenvironment. However, 3D cultures require robust and unique methods of characterization.
Methods: The goal of this study was to create a 3D spheroid model using cancer cells and macrophages, and to demonstrate a custom image analysis program to assess structural and metabolic changes across spheroid microregions.
Results: Structural characterization shows that cells at the necrotic core show high normalized fluorescence intensities of CD206 (M2 macrophages), cellular apoptosis (cleaved caspase-3, CC3), and hypoxia (HIF-1α and HIF-2α) compared to the proliferative edge, which shows high normalized fluorescence intensities of CD80 (M1 macrophages) and cellular proliferation (Ki67). Metabolic characterization was performed using multiphoton microscopy and fluorescence lifetime imaging (FLIM). Results show that the mean NADH lifetime at the necrotic core (1.011 ± 0.086 ns) was lower than that at the proliferative edge (1.105 ± 0.077 ns). The opposite trend is shown in the A1/A2 ratio (necrotic core: 4.864 ± 0.753; proliferative edge: 4.250 ± 0.432).
Conclusion: Overall, the results of this study show that 3D multicellular spheroid models can provide a reliable solution for studying tumor biology, allowing for the evaluation of discrete changes across all spheroid microregions.

Keywords:  Autofluorescence; Fluorescence microscopy; Macrophage; Metabolism; Multicellular spheroids

DOI:  https://doi.org/10.1007/s44164-024-00074-3