Adaptive mitochondrial regulation of the proteasome

SummaryThe proteasome is the main proteolytic system for targeted protein degradation in the cell. Its function is fine-tuned according to cellular needs. Regulation of proteasome function by mitochondrial metabolism, however, is unknown.Here, we demonstrate that mitochondrial dysfunction reduces the assembly and activity of the 26S proteasome in the absence of oxidative stress. Impaired respiratory complex I function leads to metabolic reprogramming of the Krebs cycle and deficiency in aspartate. Aspartate supplementation activates assembly and activity of 26S proteasomes via transcriptional activation of the proteasome assembly factors p28 and Rpn6. This metabolic adaptation of 26S proteasome function involves sensing of aspartate via the mTORC1 pathway. Metformin treatment of primary human cells similarly reduced assembly and activity of 26S proteasome complexes, which was fully reversible and rescued by supplementation of aspartate or pyruvate. Of note, respiratory dysfunction conferred resistance towards the proteasome inhibitor Bortezomib.Our study uncovers a fundamental novel mechanism of how mitochondrial metabolism adaptively adjusts protein degradation by the proteasome. It thus unravels unexpected consequences of defective mitochondrial metabolism in disease or drug-targeted mitochondrial reprogramming for proteasomal protein degradation in the cell. As metabolic inhibition of proteasome function can be alleviated by treatment with aspartate or pyruvate, our results also have therapeutic implications.

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The Role of Sodium Hydrogen Exchanger 1 in Dysregulation of Proton Dynamics and Reprogramming of Cancer Metabolism as a Sequela

International Journal of Molecular Sciences ◽

10.3390/ijms20153694 ◽

2019 ◽

Vol 20 (15) ◽

pp. 3694 ◽

Cited By ~ 9

Author(s):

Rosa Cardone ◽

Khalid Alfarouk ◽

Robert Elliott ◽

Saad Alqahtani ◽

Samrein Ahmed ◽

...

Keyword(s):

Cancer Cells ◽

Cell Biology ◽

Cancer Metabolism ◽

Cellular Proliferation ◽

Cell Metabolism ◽

Krebs Cycle ◽

Building Blocks ◽

Metabolic Reprogramming ◽

Metabolic Adaptation ◽

Sodium Hydrogen Exchanger

Cancer cells have an unusual regulation of hydrogen ion dynamics that are driven by poor vascularity perfusion, regional hypoxia, and increased glycolysis. All these forces synergize/orchestrate together to create extracellular acidity and intracellular alkalinity. Precisely, they lead to extracellular pH (pHe) values as low as 6.2 and intracellular pH values as high as 8. This unique pH gradient (∆pHi to ∆pHe) across the cell membrane increases as the tumor progresses, and is markedly displaced from the electrochemical equilibrium of protons. These unusual pH dynamics influence cancer cell biology, including proliferation, metastasis, and metabolic adaptation. Warburg metabolism with increased glycolysis, even in the presence of Oxygen with the subsequent reduction in Krebs’ cycle, is a common feature of most cancers. This metabolic reprogramming confers evolutionary advantages to cancer cells by enhancing their resistance to hypoxia, to chemotherapy or radiotherapy, allowing rapid production of biological building blocks that support cellular proliferation, and shielding against damaging mitochondrial free radicals. In this article, we highlight the interconnected roles of dysregulated pH dynamics in cancer initiation, progression, adaptation, and in determining the programming and re-programming of tumor cell metabolism.

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The Engaged Role of Tumor Microenvironment in Cancer Metabolism: Focusing on Cancer-Associated Fibroblast and Exosome Mediators

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520620666200910123428 ◽

2020 ◽

Vol 21 (2) ◽

pp. 254-266 ◽

Cited By ~ 1

Author(s):

Khandan Ilkhani ◽

Milad Bastami ◽

Soheila Delgir ◽

Asma Safi ◽

Shahrzad Talebian ◽

...

Keyword(s):

Tumor Microenvironment ◽

Cancer Cells ◽

Cancer Metabolism ◽

Krebs Cycle ◽

Metabolic Reprogramming ◽

Cancer Management ◽

Cancer Associated Fibroblast ◽

Potential Biomarker ◽

Close Relationship ◽

Microenvironmental Factors

: Metabolic reprogramming is a significant property of various cancer cells, which most commonly arises from the Tumor Microenvironment (TME). The events of metabolic pathways include the Warburg effect, shifting in Krebs cycle metabolites, and the rate of oxidative phosphorylation, potentially providing energy and structural requirements for the development and invasiveness of cancer cells. TME and tumor metabolism shifting have a close relationship through bidirectional signaling pathways between stromal and tumor cells. Cancer- Associated Fibroblasts (CAFs), as the most dominant cells of TME, play a crucial role in the aberrant metabolism of cancer. Furthermore, the stated relationship can affect survival, progression, and metastasis in cancer development. Recently, exosomes are considered one of the most prominent factors in cellular communications considering effective content and bidirectional mediatory effect between tumor and stromal cells. In this regard, CAF-Derived Exosomes (CDE) exhibit an efficient obligation to induce metabolic reprogramming for promoting growth and metastasis of cancer cells. The understanding of cancer metabolism, including factors related to TME, could lead to the discovery of a potential biomarker for diagnostic and therapeutic approaches in cancer management. This review focuses on the association between metabolic reprogramming and engaged microenvironmental, factors such as CAFs, and the associated derived exosomes.

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Abstract 15978: Acetyl-coa Catalysis by Atp-citrate Lyase is Essential for Myofibroblast Differentiation and Persistence

Circulation ◽

10.1161/circ.142.suppl_3.15978 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Michael P Lazaropoulos ◽

Andrew A Gibb ◽

Anh Huynh ◽

Kathryn Wellen ◽

John W Elrod

Keyword(s):

Histone Acetylation ◽

Transcriptional Activation ◽

Cardiac Fibrosis ◽

Transforming Growth Factor ◽

Metabolic Reprogramming ◽

Myofibroblast Differentiation ◽

Atp Citrate Lyase ◽

Acetyl Coa ◽

Matrix Deposition ◽

Citrate Lyase

A feature of heart failure (HF) is excessive extracellular matrix deposition and cardiac remodeling by a differentiated fibroblast population known as myofibroblasts. Identifying mechanisms of myofibroblast differentiation in cardiac fibrosis could yield novel therapeutic targets to delay or reverse HF. Recent evidence suggests that myofibroblast differentiation requires metabolic reprogramming for transcriptional activation of the myofibroblast gene program by chromatin-dependent mechanisms. We previously reported that inhibition of histone demethylation blocks myofibroblast formation, however, whether histone acetylation (e.g., H3K27ac, a prominent mark associated with gene transcription) is involved in fibroblast reprogramming remains unclear. ATP-citrate lyase (ACLY) synthesizes acetyl-CoA and therein supplies acetyl-CoA to the nucleus, where it is used as a substrate by histone acetyltransferases (HATs). To define the role of acetyl-CoA metabolism in myofibroblast differentiation, we stimulated differentiation in mouse embryonic fibroblasts (MEFs) and adult mouse cardiac fibroblasts (ACFs) with the pro-fibrotic agonist transforming growth factor β (TGFβ) and treated cells with a pharmacological inhibitor of ACLY. ACLY inhibition decreased myofibroblast gene expression in ACF and MEFs in TGFβ-stimulated myofibroblast differentiation, in addition to decreasing the population of αSMA positive MEFs. Genetic deletion of ACLY in MEFs recapitulated the results observed with pharmacological inhibition. Encouragingly, the ACLY inhibitor was sufficient to revert fully differentiated myofibroblasts under continuous TGFβ stimulation to a quiescent, non-fibrotic phenotype. Altogether, our data indicate that ACLY activity is necessary for myofibroblast differentiation and persistence. We hypothesize that ACLY-dependent acetyl-CoA synthesis is necessary for histone acetylation and transcriptional activation of the myofibroblast gene program. Currently, we are examining mechanisms of ACLY-dependent chromatin remodeling in fibroblasts and the in vivo relevance of this mechanism in mutant mice. In summary, ACLY is a potential target to reverse cardiac fibrosis and lessen HF.

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Ccr4 is a novel shuttle factor required for ubiquitin-dependent proteolysis by the 26S proteasome

10.1101/2020.03.30.015370 ◽

2020 ◽

Author(s):

Ganapathi Kandasamy ◽

Ashis Kumar Pradhan ◽

R Palanimurugan

Keyword(s):

Saccharomyces Cerevisiae ◽

Protein Degradation ◽

Ubiquitin Proteasome System ◽

Proteasomal Degradation ◽

Rna Degradation ◽

26S Proteasome ◽

Cellular Proteins ◽

Cellular Homeostasis ◽

Substrate Degradation ◽

Ubiquitin Proteasome

AbstractDegradation of short-lived and abnormal proteins are essential for normal cellular homeostasis. In eukaryotes, such unstable cellular proteins are selectively degraded by the ubiquitin proteasome system (UPS). Furthermore, abnormalities in protein degradation by the UPS have been linked to several human diseases. Ccr4 protein is a known component of the Ccr4-Not complex, which has established roles in transcription, mRNA de-adenylation and RNA degradation etc. Excitingly in this study, we show that Ccr4 protein has a novel function as a shuttle factor that promotes ubiquitin-dependent degradation of short-lived proteins by the 26S proteasome. Using a substrate of the well-studied ubiquitin fusion degradation (UFD) pathway, we found that its UPS-mediated degradation was severely impaired upon deletion of CCR4 in Saccharomyces cerevisiae. Additionally, we show that Ccr4 binds to cellular ubiquitin conjugates and the proteasome. In contrast to Ccr4, most other subunits of the Ccr4-Not complex proteins are dispensable for UFD substrate degradation. From our findings we conclude that Ccr4 functions in the UPS as a shuttle factor targeting ubiquitylated substrates for proteasomal degradation.

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Coagulation Signalling and Metabolic Disorders: Lessons Learned from Animal Models

Hämostaseologie ◽

10.1055/s-0039-1688800 ◽

2019 ◽

Vol 39 (02) ◽

pp. 164-172 ◽

Cited By ~ 2

Author(s):

Thati Madhusudhan ◽

Wolfram Ruf

Keyword(s):

Insulin Resistance ◽

Clinical Studies ◽

Metabolic Disorders ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Lessons Learned ◽

Metabolic Reprogramming ◽

Metabolic Adaptation ◽

Metabolic Inflammation ◽

Cardiometabolic Disorders

AbstractNutrient excess in obesity drives metabolic reprogramming in multiple tissues involving extensive interorgan and intercellular crosstalk. Experimental and clinical studies show that prolonged nutrient excess often compromises metabolic adaptation propagating proobesogenic and proinflammatory responses. Chronic inflammation further promotes insulin resistance and associated comorbidities. Obesity and type 2 diabetes are characterized by a hypercoagulable state and clinical studies show a strong correlation of markers of coagulation activation in metabolic disorders. Coagulation protease-dependent signalling via protease-activated receptors is intimately associated with inflammation. The experimental evidence supports roles of tissue factor and G protein coupled protease-activated receptor-2 signalling in the regulation of insulin resistance and metabolic inflammation in diet-induced obesity. Likewise, increases in plasminogen activator inhibitor-1 levels and fibrin-driven inflammation promote insulin resistance in obesity. Additionally, impaired thrombomodulin-dependent protein C activation is mechanistically linked to diabetic kidney disease. Given the increased usage of direct oral anticoagulants, understanding the role of specific coagulation proteases in regulation of metabolic inflammation is highly relevant and might provide insights into the design of novel treatment regimens for patients suffering from thromboinflammatory and cardiometabolic disorders.

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Metabolic Reprogramming in Breast Cancer and Its Therapeutic Implications

Cells ◽

10.3390/cells8020089 ◽

2019 ◽

Vol 8 (2) ◽

pp. 89 ◽

Cited By ~ 29

Author(s):

Nishant Gandhi ◽

Gokul Das

Keyword(s):

Breast Cancer ◽

Estrogen Receptor Alpha ◽

Cancer Metabolism ◽

Growth Factor Receptor ◽

Standard Of Care ◽

Metabolic Reprogramming ◽

Metabolic Phenotype ◽

Current Standard ◽

Therapeutic Implications ◽

Altered Metabolism

Current standard-of-care (SOC) therapy for breast cancer includes targeted therapies such as endocrine therapy for estrogen receptor-alpha (ERα) positive; anti-HER2 monoclonal antibodies for human epidermal growth factor receptor-2 (HER2)-enriched; and general chemotherapy for triple negative breast cancer (TNBC) subtypes. These therapies frequently fail due to acquired or inherent resistance. Altered metabolism has been recognized as one of the major mechanisms underlying therapeutic resistance. There are several cues that dictate metabolic reprogramming that also account for the tumors’ metabolic plasticity. For metabolic therapy to be efficacious there is a need to understand the metabolic underpinnings of the different subtypes of breast cancer as well as the role the SOC treatments play in targeting the metabolic phenotype. Understanding the mechanism will allow us to identify potential therapeutic vulnerabilities. There are some very interesting questions being tackled by researchers today as they pertain to altered metabolism in breast cancer. What are the metabolic differences between the different subtypes of breast cancer? Do cancer cells have a metabolic pathway preference based on the site and stage of metastasis? How do the cell-intrinsic and -extrinsic cues dictate the metabolic phenotype? How do the nucleus and mitochondria coordinately regulate metabolism? How does sensitivity or resistance to SOC affect metabolic reprogramming and vice-versa? This review addresses these issues along with the latest updates in the field of breast cancer metabolism.

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228. Proteasomal activity during mouse preimplantation development

Reproduction Fertility and Development ◽

10.1071/srb08abs228 ◽

2008 ◽

Vol 20 (9) ◽

pp. 28 ◽

Cited By ~ 1

Author(s):

K. McCue ◽

M. Pantaleon ◽

P. L. Kaye

Keyword(s):

Cell Proliferation ◽

Protein Degradation ◽

Specific Treatment ◽

Preimplantation Development ◽

26S Proteasome ◽

Preimplantation Embryos ◽

Cell Cycle Regulators ◽

Loss Of Function ◽

Cell Stage ◽

Proteasomal Activity

Function of the 26S proteasome, a proteolytic organelle directed at proteins targeted for turnover by polyubiquitination, in preimplantation embryos is unclear. But it is well known to play a role in regulating meiosis. This paper reports the distribution of the proteasome and assessment of its functional importance in preimplantation development. Embryos from superovulated mice were either paraformaldehyde fixed for immunolabelling with a rabbit polyclonal antibody against the 20S proteasome core or cultured in KSOM medium with and without reversible (MG132) or irreversible (β-lactone) proteasomal inhibitors. Morphology, cell number, apoptosis and proteolysis were measured. Although diffuse throughout embryonic cytoplasm, there were distinct proteasomal concentrations in pronuclei, nuclei and cortical cytoplasm. When β-lactone was used to block blastocyst proteasomal proteolysis, ~25% of protein degradation was found to be proteasome-specific. Treatment of 2-cell embryos for more than 3 h with MG132 blocked blastocyst formation completely, even after washout, whilst both inhibitors reduced cell proliferation over the ensuing 48 h. Two hours exposure to MG132 tripled the proportion of apoptotic cells in expanded blastocysts 96 h post hCG. The nuclear concentration of proteasomes suggests a particular role in nuclear protein degradation possibly including the timed destruction of cell-cycle regulators and anti-apoptotic factors. This is supported by the loss-of-function studies which show that cell proliferation as well as morphogenesis require proteasomal activity at the late 2-cell stage and that without it apoptosis is dramatically increased. The mechanisms involved in the activation of apoptosis as a result of proteasomal inhibition in the early embryo are unknown but may include JNK signalling although this is controversial. More intriguing however is the identity of the proteasomal targets in the 2-cell embryo that must be degraded to permit continued morphogenesis.

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The Role of Selective Protein Degradation in the Regulation of Iron and Sulfur Homeostasis in Plants

International Journal of Molecular Sciences ◽

10.3390/ijms21082771 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2771 ◽

Cited By ~ 2

Author(s):

Anna Wawrzyńska ◽

Agnieszka Sirko

Keyword(s):

Protein Degradation ◽

Plant Development ◽

Sulfur Metabolism ◽

High Energy ◽

26S Proteasome ◽

Control Mechanisms ◽

Wide Range ◽

Ubiquitin Conjugation ◽

Cellular Components

Plants are able to synthesize all essential metabolites from minerals, water, and light to complete their life cycle. This plasticity comes at a high energy cost, and therefore, plants need to tightly allocate resources in order to control their economy. Being sessile, plants can only adapt to fluctuating environmental conditions, relying on quality control mechanisms. The remodeling of cellular components plays a crucial role, not only in response to stress, but also in normal plant development. Dynamic protein turnover is ensured through regulated protein synthesis and degradation processes. To effectively target a wide range of proteins for degradation, plants utilize two mechanistically-distinct, but largely complementary systems: the 26S proteasome and the autophagy. As both proteasomal- and autophagy-mediated protein degradation use ubiquitin as an essential signal of substrate recognition, they share ubiquitin conjugation machinery and downstream ubiquitin recognition modules. Recent progress has been made in understanding the cellular homeostasis of iron and sulfur metabolisms individually, and growing evidence indicates that complex crosstalk exists between iron and sulfur networks. In this review, we highlight the latest publications elucidating the role of selective protein degradation in the control of iron and sulfur metabolism during plant development, as well as environmental stresses.

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Cadmium-mediated lung injury is exacerbated by the persistence of classically activated macrophages

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.013632 ◽

2020 ◽

Vol 295 (46) ◽

pp. 15754-15766 ◽

Cited By ~ 1

Author(s):

Jennifer L. Larson-Casey ◽

Linlin Gu ◽

Oliver Fiehn ◽

A. Brent Carter

Keyword(s):

Lung Injury ◽

Respiratory Health ◽

Metabolic Reprogramming ◽

Metabolic Adaptation ◽

Glycolytic Flux ◽

Activated Macrophages ◽

Lung Macrophages ◽

Classically Activated Macrophages ◽

Inflammatory Response To Injury ◽

Classically Activated

Heavy metals released into the environment have a significant effect on respiratory health. Lung macrophages are important in mounting an inflammatory response to injury, but they are also involved in repair of injury. Macrophages develop mixed phenotypes in complex pathological conditions and polarize to a predominant phenotype depending on the duration and stage of injury and/or repair. Little is known about the reprogramming required for lung macrophages to switch between these divergent functions; therefore, understanding the mechanism(s) by which macrophages promote metabolic reprogramming to regulate lung injury is essential. Here, we show that lung macrophages polarize to a pro-inflammatory, classically activated phenotype after cadmium-mediated lung injury. Because metabolic adaptation provides energy for the diverse macrophage functions, these classically activated macrophages show metabolic reprogramming to glycolysis. RNA-Seq revealed up-regulation of glycolytic enzymes and transcription factors regulating glycolytic flux in lung macrophages from cadmium-exposed mice. Moreover, cadmium exposure promoted increased macrophage glycolytic function with enhanced extracellular acidification rate, glycolytic metabolites, and lactate excretion. These observations suggest that cadmium mediates the persistence of classically activated lung macrophages to exacerbate lung injury.

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Mitochondrial Metabolism in PDAC: From Better Knowledge to New Targeting Strategies

Biomedicines ◽

10.3390/biomedicines8080270 ◽

2020 ◽

Vol 8 (8) ◽

pp. 270 ◽

Cited By ~ 2

Author(s):

Gabriela Reyes-Castellanos ◽

Rawand Masoud ◽

Alice Carrier

Keyword(s):

Cancer Therapy ◽

Cancer Cells ◽

Cancer Progression ◽

Cancer Metabolism ◽

Aerobic Glycolysis ◽

Mitochondrial Metabolism ◽

Metabolic Reprogramming ◽

Ductal Adenocarcinoma ◽

Current View ◽

Pancreatic Cancer Cells

Cancer cells reprogram their metabolism to meet bioenergetics and biosynthetic demands. The first observation of metabolic reprogramming in cancer cells was made a century ago (“Warburg effect” or aerobic glycolysis), leading to the classical view that cancer metabolism relies on a glycolytic phenotype. There is now accumulating evidence that most cancers also rely on mitochondria to satisfy their metabolic needs. Indeed, the current view of cancer metabolism places mitochondria as key actors in all facets of cancer progression. Importantly, mitochondrial metabolism has become a very promising target in cancer therapy, including for refractory cancers such as Pancreatic Ductal AdenoCarcinoma (PDAC). In particular, mitochondrial oxidative phosphorylation (OXPHOS) is an important target in cancer therapy. Other therapeutic strategies include the targeting of glutamine and fatty acids metabolism, as well as the inhibition of the TriCarboxylic Acid (TCA) cycle intermediates. A better knowledge of how pancreatic cancer cells regulate mitochondrial metabolism will allow the identification of metabolic vulnerabilities and thus novel and more efficient therapeutic options for the benefit of each patient.

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