Showing papers on "Pyruvate kinase published in 2020"
TL;DR: In vitro and in vivo studies showed that exosomes from oxaliplatin‐resistant cells delivered ciRS‐122 to sensitive cells, thereby promoting glycolysis and drug resistance through miR‐122 sponging and PKM2 upregulation and establishing a foundation for future clinical applications in drug‐resistant CRC.
282 citations
TL;DR: The role of pyruvate kinase M2 in normal cells vs. cancerous cells and its regulation at the transcriptional level is highlighted and the role of PKM2 as a potential diagnostic marker and as a therapeutic target in cancer treatment is highlighted.
Abstract: Pyruvate kinase plays a pivotal role in regulating cell metabolism. The final and rate-limiting step of glycolysis is the conversion of Phosphoenolpyruvate (PEP) to Pyruvate, which is catalyzed by Pyruvate Kinase. There are four isomeric, tissue-specific forms of Pyruvate Kinase found in mammals: PKL, PKR, PKM1, and PKM2. PKM1 and PKM2 are formed bya single mRNA transcript of the PKM gene by alternative splicing. The oligomers of PKM2 exist in high activity tetramer and low activity dimer forms. The dimer PKM2 regulates the rate-limiting step of glycolysis that shifts the glucose metabolism from the normal respiratory chain to lactate production in tumor cells. Besides its role as a metabolic regulator, it also acts as protein kinase, which contributes to tumorigenesis. This review is focused on the metabolic role of pyruvate kinase M2 in normal cells vs. cancerous cells and its regulation at the transcriptional level. The review also highlights the role of PKM2 as a potential diagnostic marker and as a therapeutic target in cancer treatment.
209 citations
TL;DR: The results suggest that pharmacological targeting of PKM2 may represent a valuable therapeutic approach in T cell-mediated inflammation and autoimmunity.
155 citations
TL;DR: It is suggested that polystyrene nanoplastic causes the overproduction of ROS and activates the downstream pathway, resulting in inhibited growth, development, and reproduction in zooplankton.
138 citations
TL;DR: The present review attempts to address the implication of key enzymes of the aerobic glycolytic pathway including hexokin enzyme (HK), phosphofructokinase (PFK) and pyruvate kinase (PK), glucose transporters (GLUTs), together with related signaling pathways including protein kinase B(PI3K/AKT).
Abstract: Altered aerobic glycolysis is a well-recognized characteristic of cancer cell energy metabolism, known as the Warburg effect. Even in the presence of abundant oxygen, a majority of tumor cells produce substantial amounts of energy through a high glycolytic metabolism, and breast cancer (BC) is no exception. Breast cancer continues to be the second leading cause of cancer-associated mortality in women worldwide. However, the precise role of aerobic glycolysis in the development of BC remains elusive. Therefore, the present review attempts to address the implication of key enzymes of the aerobic glycolytic pathway including hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK), glucose transporters (GLUTs), together with related signaling pathways including protein kinase B(PI3K/AKT), mammalian target of rapamycin (mTOR) and adenosine monophosphate-activated protein kinase (AMPK) and transcription factors (c-myc, p53 and HIF-1) in the research of BC. Thus, the review of aerobic glycolysis in BC may evoke novel ideas for the BC treatment.
111 citations
TL;DR: Taken together, SGLT2 inhibitors exhibit renoprotective potential that is partially dependent on the inhibition of glucose reabsorption and subsequent aberrant glycolysis in kidney tubules.
Abstract: Sodium glucose cotransporter 2 (SGLT2) inhibitors are beneficial in halting diabetic kidney disease; however, the complete mechanisms have not yet been elucidated. The epithelial-mesenchymal transition (EMT) is associated with the suppression of sirtuin 3 (Sirt3) and aberrant glycolysis. Here, we hypothesized that the SGLT2 inhibitor empagliflozin restores normal kidney histology and function in association with the inhibition of aberrant glycolysis in diabetic kidneys. CD-1 mice with streptozotocin-induced diabetes displayed kidney fibrosis that was associated with the EMT at 4 months after diabetes induction. Empagliflozin intervention for 1 month restored all pathological changes; however, adjustment of blood glucose by insulin did not. Empagliflozin normalized the suppressed Sirt3 levels and aberrant glycolysis that was characterized by HIF-1α accumulation, hexokinase 2 induction, and pyruvate kinase isozyme M2 dimer formation in diabetic kidneys. Empagliflozin also suppressed the accumulation of glycolysis byproducts in diabetic kidneys. Another SGLT2 inhibitor, canagliflozin, demonstrated similar in vivo effects. High-glucose media induced the EMT, which was associated with Sirt3 suppression and aberrant glycolysis induction, in the HK2 proximal tubule cell line; SGLT2 knockdown suppressed the EMT, with restoration of all aberrant functions. SGLT2 suppression in tubular cells also inhibited the mesenchymal transition of neighboring endothelial cells. Taken together, SGLT2 inhibitors exhibit renoprotective potential that is partially dependent on the inhibition of glucose reabsorption and subsequent aberrant glycolysis in kidney tubules.
111 citations
TL;DR: It is shown that pyruvate kinase (PK) underlies β cell sensing of both glycolytic and mitochondrial fuels and suggests a potential therapeutic route for diabetes based on PK activation that would not be predicted by the current consensus single-state model of β cell function.
79 citations
TL;DR: The simultaneous restriction of glucose and glutamine offers a therapeutic strategy for managing cancer by partially compensate for reduced ATP synthesis through both OxPhos and glycolysis.
58 citations
TL;DR: It is shown that protein arginine N‐methyltransferase 6 (PRMT6) regulates aerobic glycolysis in human hepatocellular carcinoma (HCC) through nuclear relocalization of pyruvate kinase M2 isoform (PKM2), a key regulator of the Warburg effect.
56 citations
TL;DR: The findings reveal new roles for cardiac metabolism and the PDK‐PDC axis in cardiomyocyte behavior following cardiac injury and find that PDK activity can modulate cell cycle progression and protrusive activity in mammalianCardiomyocytes in culture.
Abstract: Cardiac metabolism plays a crucial role in producing sufficient energy to sustain cardiac function. However, the role of metabolism in different aspects of cardiomyocyte regeneration remains unclear. Working with the adult zebrafish heart regeneration model, we first find an increase in the levels of mRNAs encoding enzymes regulating glucose and pyruvate metabolism, including pyruvate kinase M1/2 (Pkm) and pyruvate dehydrogenase kinases (Pdks), especially in tissues bordering the damaged area. We further find that impaired glycolysis decreases the number of proliferating cardiomyocytes following injury. These observations are supported by analyses using loss-of-function models for the metabolic regulators Pkma2 and peroxisome proliferator-activated receptor gamma coactivator 1 alpha. Cardiomyocyte-specific loss- and gain-of-function manipulations of pyruvate metabolism using Pdk3 as well as a catalytic subunit of the pyruvate dehydrogenase complex (PDC) reveal its importance in cardiomyocyte dedifferentiation and proliferation after injury. Furthermore, we find that PDK activity can modulate cell cycle progression and protrusive activity in mammalian cardiomyocytes in culture. Our findings reveal new roles for cardiac metabolism and the PDK-PDC axis in cardiomyocyte behavior following cardiac injury.
55 citations
TL;DR: Serotonin, through 5-HTR 2A/C , interferes with breast cancer cells proliferation and metabolism by triggering two distinct signalling pathways: Jak1/STAT3 that boosts glycolysis through upregulation of PKM2, and adenylyl cyclase/PKA that enhances mitochondrial biogenesis.
Abstract: Although produced by several types of tumours, the role of serotonin on cancer biology is yet to be understood. The effects of serotonin (5-HT) on human breast cancer cells proliferation, signalling pathways and metabolic profile were evaluated by cytometry, western blotting, qPCR, enzymology and confocal microscopy. Our results revealed that incubation of MCF-7 cells with 10 µM 5-HT increased cell growth rate by 28%, an effect that was prevented by the 5-HTR2A/C antagonist, ketanserin. Conversely, increasing concentrations of 5-HT promoted glucose consumption and lactate production by MCF-7 cells. We also showed that increased glucose metabolism is provoked by the upregulation of pyruvate kinase M2 (PKM2) isoform through 5-HTR2A/C-triggered activation of Jak1/STAT3 and ERK1/2 subcellular pathways. However, we noticed a decrease in the rate of produced lactate per consumed glucose as a function of the hormone concentration, suggesting a disruption of the Warburg effect. The latter effect is due to 5-HTR2A/C-dependent mitochondrial biogenesis and metabolism, which is triggered by adenylyl cyclase/PKA, enhancing the oxidation of lactate within these cells. We showed that serotonin, through 5-HTR2A/C, interferes with breast cancer cells proliferation and metabolism by triggering two distinct signalling pathways: Jak1/STAT3 that boosts glycolysis through upregulation of PKM2, and adenylyl cyclase/PKA that enhances mitochondrial biogenesis.
TL;DR: Four-week delivery of a PK activator in vivo remodeled PK phosphorylation, reduced liver fat, and improved hepatic and peripheral insulin sensitivity in HFD-fed rats provides a preclinical rationale for PK activation to accelerate the PEP cycle to improve metabolic homeostasis and insulin sensitivity.
TL;DR: It is shown that an Hdac7-Pkm2 complex acts as an immunometabolism signaling hub, whereby Pkm2 deacetylation at lysine 433 licenses its proinflammatory functions, and disrupting this complex suppresses inflammatory responses in vitro and in–vivo.
TL;DR: Evidence is provided that phosphoglycerate mutase and enolase form a substrate-channelling metabolon which is part of a larger complex of proteins including pyruvate kinase, which contributes to the co-localization of mitochondria and chloroplasts.
Abstract: Glycolysis is one of the primordial pathways of metabolism, playing a pivotal role in energy metabolism and biosynthesis. Glycolytic enzymes are known to form transient multi-enzyme assemblies. Here we examine the wider protein-protein interactions of plant glycolytic enzymes and reveal a moonlighting role for specific glycolytic enzymes in mediating the co-localization of mitochondria and chloroplasts. Knockout mutation of phosphoglycerate mutase or enolase resulted in a significantly reduced association of the two organelles. We provide evidence that phosphoglycerate mutase and enolase form a substrate-channelling metabolon which is part of a larger complex of proteins including pyruvate kinase. These results alongside a range of genetic complementation experiments are discussed in the context of our current understanding of chloroplast-mitochondrial interactions within photosynthetic eukaryotes.
TL;DR: Understanding the molecular mechanism regulating mitochondrial metabolism and dynamics has permitted identification of new biomarkers, nuclear and CT imaging modalities, and new therapeutic targets for PAH.
Abstract: In lung vascular cells, mitochondria serve a canonical metabolic role, governing energy homeostasis. In addition, mitochondria exist in dynamic networks, which serve noncanonical functions, including regulation of redox signaling, cell cycle, apoptosis, and mitochondrial quality control. Mitochondria in pulmonary artery smooth muscle cells (PASMC) are oxygen sensors and initiate hypoxic pulmonary vasoconstriction. Acquired dysfunction of mitochondrial metabolism and dynamics contribute to a cancer-like phenotype in pulmonary arterial hypertension (PAH). Acquired mitochondrial abnormalities, such as increased pyruvate dehydrogenase kinase (PDK) and pyruvate kinase muscle isoform 2 (PKM2) expression, which increase uncoupled glycolysis (the Warburg phenomenon), are implicated in PAH. Warburg metabolism sustains energy homeostasis by the inhibition of oxidative metabolism that reduces mitochondrial apoptosis, allowing unchecked cell accumulation. Warburg metabolism is initiated by the induction of a pseudohypoxic state, in which DNA methyltransferase (DNMT)-mediated changes in redox signaling cause normoxic activation of HIF-1α and increase PDK expression. Furthermore, mitochondrial division is coordinated with nuclear division through a process called mitotic fission. Increased mitotic fission in PAH, driven by increased fission and reduced fusion favors rapid cell cycle progression and apoptosis resistance. Downregulation of the mitochondrial calcium uniporter complex (MCUC) occurs in PAH and is one potential unifying mechanism linking Warburg metabolism and mitochondrial fission. Mitochondrial metabolic and dynamic disorders combine to promote the hyperproliferative, apoptosis-resistant, phenotype in PAH PASMC, endothelial cells, and fibroblasts. Understanding the molecular mechanism regulating mitochondrial metabolism and dynamics has permitted identification of new biomarkers, nuclear and CT imaging modalities, and new therapeutic targets for PAH. © 2020 American Physiological Society. Compr Physiol 10:713-765, 2020.
TL;DR: Results indicate that vitamin D-activated MEG3 suppresses aerobic glycolysis in CRC cells via degradation of c-Myc, and vitamin D may have therapeutic value in the treatment of CRC.
Abstract: Colorectal cancer (CRC), a common tumor, is characterized by a high mortality rate. Long non-coding RNA maternally expressed gene 3 (MEG3) serves a regulatory role in the carcinogenesis and progression of several types of cancer; however, its role in CRC remains largely unknown. The aim of this study was to explore the regulatory role and mechanism(s) of MEG3 in CRC. The Warburg effect or aerobic glycolysis is characteristic of the metabolism of tumor cells. To determine the effect of MEG3 on glycolysis of CRC cells, we used an XF analyzer to perform glycolysis stress test assays and found that overexpression of MEG3 significantly inhibited glycolysis, glycolytic capacity, as well as lactate production in CRC cells, whereas knockdown of MEG3 produced the opposite effect. Mechanistically, overexpression of MEG3 induced ubiquitin-dependent degradation of c-Myc and inhibited c-Myc target genes involved in the glycolysis pathway such as lactate dehydrogenase A, pyruvate kinase muscle 2, and hexokinase 2. Moreover, we found that MEG3 can be activated by vitamin D and vitamin D receptor (VDR). Clinical data demonstrated that MEG3 was positively associated with serum vitamin D concentrations in patients with CRC. We found that 1,25(OH)2D3 treatment increased MEG3 expression, and knockdown of VDR abolished the effect of MEG3 on glycolysis. These results indicate that vitamin D-activated MEG3 suppresses aerobic glycolysis in CRC cells via degradation of c-Myc. Thus, vitamin D may have therapeutic value in the treatment of CRC.
TL;DR: It is reported that OGA is upregulated in a wide range of human cancers and drives aerobic glycolysis and tumor growth by inhibiting pyruvate kinase M2 (PKM2) and revealed PKM2 O-GlcNAcylation as a metabolic rheostat that mediates exquisite control of aerobic glyCOlysis.
Abstract: Cancer cells are known to adopt aerobic glycolysis in order to fuel tumor growth, but the molecular basis of this metabolic shift remains largely undefined. O-GlcNAcase (OGA) is an enzyme harboring O-linked β-N-acetylglucosamine (O-GlcNAc) hydrolase and cryptic lysine acetyltransferase activities. Here, we report that OGA is upregulated in a wide range of human cancers and drives aerobic glycolysis and tumor growth by inhibiting pyruvate kinase M2 (PKM2). PKM2 is dynamically O-GlcNAcylated in response to changes in glucose availability. Under high glucose conditions, PKM2 is a target of OGA-associated acetyltransferase activity, which facilitates O-GlcNAcylation of PKM2 by O-GlcNAc transferase (OGT). O-GlcNAcylation inhibits PKM2 catalytic activity and thereby promotes aerobic glycolysis and tumor growth. These studies define a causative role for OGA in tumor progression and reveal PKM2 O-GlcNAcylation as a metabolic rheostat that mediates exquisite control of aerobic glycolysis.
TL;DR: The results illustrate the potential of INST-MFA to enable a systematic approach for iterative identification and removal of pathway bottlenecks in autotrophic host cells.
TL;DR: The nuclear localization of PKM2, its protein kinase function and association with cancers, and regulation ofPKM2 activity are discussed.
Abstract: Pyruvate kinase is a terminal enzyme in the glycolytic pathway, where it catalyzes the conversion of phosphoenolpyruvate to pyruvate and production of ATP via substrate level phosphorylation. PKM2 is one of four isoforms of pyruvate kinase and is widely expressed in many types of tumors and associated with tumorigenesis. In addition to pyruvate kinase activity involving the metabolic pathway, increasing evidence demonstrates that PKM2 exerts a non-metabolic function in cancers. PKM2 has been shown to be translocated into nucleus, where it serves as a protein kinase to phosphorylate various protein targets and contribute to multiple physiopathological processes. We discuss the nuclear localization of PKM2, its protein kinase function and association with cancers, and regulation of PKM2 activity.
TL;DR: In this paper, the authors performed a proteomic analysis on OsSPL16/qGW8 mutants and found that the mutants were generated with two separate guide RNAs targeting recognition sites on opposite strands and genomic insertions and deletions were characterized.
Abstract: Rice (Oryza sativa L.) is one of the major crops in the world and significant increase in grain yield is constant demand for breeders to meet the needs of a rapidly growing population. The size of grains is one of major components determining rice yield and a vital trait for domestication and breeding. To increase the grain size in rice, OsSPL16/qGW8 was mutagenized through CRISPR/Cas9, and proteomic analysis was performed to reveal variations triggered by mutations. More specifically, mutants were generated with two separate guide RNAs targeting recognition sites on opposite strands and genomic insertions and deletions were characterized. Mutations followed Mendelian inheritance and homozygous and heterozygous mutants lacking any T-DNA and off-target effects were screened. The mutant lines showed a significant increase in grain yield without any change in other agronomic traits in T0, T1, and T2 generations. Proteomic screening found a total of 44 differentially expressed proteins (DEPs), out of which 33 and 11 were up and downregulated, respectively. Most of the DEPs related to pyruvate kinase, pyruvate dehydrogenase, and cell division and proliferation were upregulated in the mutant plants. Pathway analysis revealed that DEPs were enriched in the biosynthesis of secondary metabolites, pyruvate metabolism, glycolysis/gluconeogenesis, carbon metabolism, ubiquinone and other terpenoid-quinone biosynthesis, and citrate cycle. Gene Ontology (GO) analysis presented that most of the DEPs were involved in the pyruvate metabolic process and pyruvate dehydrogenase complex. Proteins related to pyruvate dehydrogenase E1 component subunit alpha-1 displayed higher interaction in the protein-protein interaction (PPI) network. Thus, the overall results revealed that CRISPR/Cas9-guided OsSPL16 mutations have the potential to boost the grain yield of rice. Additionally, global proteome analysis has broad applications for discovering molecular components and dynamic regulation underlying the targeted gene mutations.
TL;DR: Cutting off the PKM2-derived ATP supply to the PMCA represents a novel therapeutic strategy for the treatment of Pancreatic ductal adenocarcinoma.
Abstract: Pancreatic ductal adenocarcinoma (PDAC) has poor survival and treatment options. PDAC cells shift their metabolism towards glycolysis, which fuels the plasma membrane calcium pump (PMCA), thereby preventing Ca2+-dependent cell death. The ATP-generating pyruvate kinase-M2 (PKM2) is oncogenic and overexpressed in PDAC. This study investigated the PKM2-derived ATP supply to the PMCA as a potential therapeutic locus. PDAC cell growth, migration and death were assessed by using sulforhodamine-B/tetrazolium-based assays, gap closure assay and poly-ADP ribose polymerase (PARP1) cleavage, respectively. Cellular ATP and metabolism were assessed using luciferase/fluorescent-based assays and the Seahorse XFe96 analyzer, respectively. Cell surface biotinylation identified membrane-associated proteins. Fura-2 imaging was used to assess cytosolic Ca2+ overload and in situ Ca2+ clearance. PKM2 knockdown was achieved using siRNA. The PKM2 inhibitor (shikonin) reduced PDAC cell proliferation, cell migration and induced cell death. This was due to inhibition of glycolysis, ATP depletion, inhibition of PMCA and cytotoxic Ca2+ overload. PKM2 associates with plasma membrane proteins providing a privileged ATP supply to the PMCA. PKM2 knockdown reduced PMCA activity and reduced the sensitivity of shikonin-induced cell death. Cutting off the PKM2-derived ATP supply to the PMCA represents a novel therapeutic strategy for the treatment of PDAC.
TL;DR: The hypothesis that drug intervention with AG- 348 effectively up-regulates PK enzymatic activity and increases stability in PK-deficient RBC over a broad range of PKLR genotypes is supported.
Abstract: Pyruvate kinase (PK) deficiency is a rare hereditary disorder affecting red cell (RBC) glycolysis, causing changes in metabolism including a deficiency in ATP. This affects red cell homeostasis, promoting premature removal of RBCs from the circulation. In this study we characterized and evaluated the effect of AG-348, an allosteric activator of PK that is currently in clinical trials for treatment of PK deficiency, on RBCs and erythroid precursors from PK-deficient patients. In 15 patients ex vivo treatment with AG-348 resulted in increased enzymatic activity in all patient cells after 24 hours (mean increase 1.8-fold, range 1.2-3.4). ATP levels increased (mean increase 1.5-fold, range 1.0-2.2) similar to control cells (mean increase 1.6-fold, range, 1.4-1.8). Generally, PK thermostability was strongly reduced in PK-deficient RBCs. Ex vivo treatment with AG-348 increased residual activity 1.4 to >10-fold than residual activity of vehicle-treated samples. Protein analyses suggests that a sufficient level of PK protein is required for cells to respond to AG-348 treatment ex-vivo, as treatment effects were minimal in patient cells with very low or undetectable levels of PK-R. In half of the patients, ex vivo treatment with AG-348 was associated with an increase in RBC deformability. These data support the hypothesis that drug intervention with AG-348 effectively upregulates PK enzymatic activity and increases stability in PK-deficient RBCs over a broad range of PKLR genotypes. The concomitant increase in ATP levels suggests that glycolytic pathway activity may be restored. AG-348 treatment may represent an attractive way to correct the underlying pathologies of PK deficiency. (AG-348 is currently in clinical trials for the treatment of PK deficiency. ClinicalTrials.gov: NCT02476916, NCT03853798, NCT03548220, NCT03559699).
TL;DR: It was demonstrated that suppression of PKM2 expression diminishes the efficacy of Ben in inhibition of melanoma cell growth; ectopic PKM1 expression in normal cells sensitizes cells to Ben treatment, and Interestingly, PKM 2 activity and aerobic glycolysis are upregulated in BRAFi‐resistant melanoma cells.
Abstract: The M2 splice isoform of pyruvate kinase (PKM2) is a key enzyme for generating pyruvate and ATP in the glycolytic pathway, whereas the role of PKM2 in tumorigenesis remains a subject of debate. In our study, we found PKM2 is highly expressed in melanoma patients and the malignance is positively correlated with high PKM2 activity and glycolytic capability in melanoma cells. Suppression of PKM2 expression by knocking down markedly attenuated malignant phenotype both in vitro and in vivo, and restoration of PKM2 expression in PKM2 depleted cells could rescue melanoma cells proliferation, invasion and metastasis. With the data indicating PKM2 as a potential therapeutic target, we performed screening for PKM2 inhibitors and identified benserazide (Ben), a drug currently in clinical use. We demonstrated that Ben directly binds to and blocks PKM2 enzyme activity, leading to inhibition of aerobic glycolysis concurrent up-regulation of OXPHOS. Of note, despite PKM2 is very similar to PKM1, Ben does not affect PKM1 enzyme activity. We showed that Ben significantly inhibits cell proliferation, colony formation, invasion and migration in vitro and in vivo. The specificity of Ben was demonstrated by the findings that, suppression of PKM2 expression diminishes the efficacy of Ben in inhibition of melanoma cell growth; ectopic PKM2 expression in normal cells sensitizes cells to Ben treatment. Interestingly, PKM2 activity and aerobic glycolysis are upregulated in BRAFi-resistant melanoma cells. As a result, BRAFi-resistant cells exhibit heightened sensitivity to suppression of PKM2 expression or treatment with Ben both in vitro and in vivo.
TL;DR: Mammalian target of rapamycin (mTOR) is identified as a critical regulator of PKM2 during podocyte development, and a stronger glycolytic profile is observed, accompanied by an increased mitochondrial complexity in differentiated podocytes, indicating that mature podocytes boost both gly colysis and mitochondrial metabolism to meet their augmented energy demands.
Abstract: Podocytes, a type of highly specialized epithelial cells, require substantial levels of energy to maintain glomerular integrity and function, but little is known on the regulation of podocytes’ energetics. Lack of metabolic analysis during podocyte development led us to explore the distribution of mitochondrial oxidative phosphorylation and glycolysis, the two major pathways of cell metabolism, in cultured podocytes during in vitro differentiation. Unexpectedly, we observed a stronger glycolytic profile, accompanied by an increased mitochondrial complexity in differentiated podocytes, indicating that mature podocytes boost both glycolysis and mitochondrial metabolism to meet their augmented energy demands. In addition, we found a shift of predominant energy source from anaerobic glycolysis in immature podocyte to oxidative phosphorylation during the differentiation process. Furthermore, we identified a crucial metabolic regulator for podocyte development, pyruvate kinase M2. Pkm2-knockdown podocytes showed dramatic reduction of energy metabolism, resulting in defects of cell differentiation. Meanwhile, podocyte-specific Pkm2-knockout (KO) mice developed worse albuminuria and podocyte injury after adriamycin treatment. We identified mammalian target of rapamycin (mTOR) as a critical regulator of PKM2 during podocyte development. Pharmacological inhibition of mTOR potently abrogated PKM2 expression and disrupted cell differentiation, indicating the existence of metabolic checkpoint that need to be satisfied in order to allow podocyte differentiation.
TL;DR: This review focuses on the metabolic and non-metabolic roles of pyruvate kinases in photoreceptor cell functions and compares these cells to actively growing mitotic tumor cells.
Abstract: One hundred years ago, Otto Heinrich Warburg observed that postmitotic retinal cells are the highest oxygen-consuming cells in the body. He compared these cells to actively growing mitotic tumor cells since both cells reprogram glucose for anabolic processes, which include lipid, protein, and RNA/DNA synthesis, and for antioxidant metabolism. To achieve this metabolic reprogramming, cancer cells preferentially express a less active dimeric form, the M2 isoform of pyruvate kinase (PKM2), which shuttles glucose toward the accumulation of glycolytic intermediates that redirect cell activities into anabolic processes. Similar to cancer cells, retinal photoreceptors predominantly express the M2 isoform of PKM2. This isoform performs both metabolic and non-metabolic functions in photoreceptor cells. This review focuses on the metabolic and non-metabolic roles of pyruvate kinases in photoreceptor cell functions.
TL;DR: Transcriptome analysis reveals the multiple defensive mechanism for carbon metabolism in response to nitrogen starvation, which extended the understanding on the carotenoids, TAG and other important metabolites synthesis.
TL;DR: In this paper, the effects of CO2 enrichment (800 ± 40 μmol·mol−1) on sucrose metabolism, the glycolytic pathway, and tricarboxylic acid (TCA) cycle intermediates and their key enzyme activities in leaves of cucumber (Cucumis sativus L. cv. 35′) seedlings under salt stress (80 mmol·L−1 NaCl) in solution cultures were investigated.
TL;DR: In this article, the authors examined the impact of pyruvate kinase M2 on the pathogenesis of house dust mite-induced allergic airway disease in C57BL/6NJ mice.
Abstract: Asthma is a chronic disorder characterized by inflammation, mucus metaplasia, airway remodeling, and hyperresponsiveness. We recently showed that IL-1-induced glycolytic reprogramming contributes to allergic airway disease using a murine house dust mite model. Moreover, levels of pyruvate kinase M2 (PKM2) were increased in this model as well as in nasal epithelial cells from asthmatics as compared with healthy controls. Although the tetramer form of PKM2 converts phosphoenolpyruvate to pyruvate, the dimeric form of PKM2 has alternative, nonglycolysis functions as a transcriptional coactivator to enhance the transcription of several proinflammatory cytokines. In the current study, we examined the impact of PKM2 on the pathogenesis of house dust mite-induced allergic airways disease in C57BL/6NJ mice. We report, in this study, that activation of PKM2, using the small molecule activator, TEPP46, augmented PKM activity in lung tissues and attenuated airway eosinophils, mucus metaplasia, and subepithelial collagen. TEPP46 attenuated IL-1β-mediated airway inflammation and expression of proinflammatory mediators. Exposure to TEPP46 strongly decreased the IL-1β-mediated increases in thymic stromal lymphopoietin (TSLP) and GM-CSF in primary tracheal epithelial cells isolated from C57BL/6NJ mice. We also demonstrate that IL-1β-mediated increases in nuclear phospho-STAT3 were decreased by TEPP46. Finally, STAT3 inhibition attenuated the IL-1β-induced release of TSLP and GM-CSF, suggesting that the ability of PKM2 to phosphorylate STAT3 contributes to its proinflammatory function. Collectively, these results demonstrate that the glycolysis-inactive form of PKM2 plays a crucial role in the pathogenesis of allergic airways disease by increasing IL-1β-induced proinflammatory signaling, in part, through phosphorylation of STAT3.
TL;DR: The genetic tuning of glycolytic flux may reflect an adaptive trade‐off in a species lacking pyruvate kinase isoforms, and low Pyk1 activity does not lead to a growth advantage but to stress tolerance.
Abstract: Cells balance glycolysis with respiration to support their metabolic needs in different environmental or physiological contexts. With abundant glucose, many cells prefer to grow by aerobic glycolysis or fermentation. Using 161 natural isolates of fission yeast, we investigated the genetic basis and phenotypic effects of the fermentation-respiration balance. The laboratory and a few other strains depended more on respiration. This trait was associated with a single nucleotide polymorphism in a conserved region of Pyk1, the sole pyruvate kinase in fission yeast. This variant reduced Pyk1 activity and glycolytic flux. Replacing the "low-activity" pyk1 allele in the laboratory strain with the "high-activity" allele was sufficient to increase fermentation and decrease respiration. This metabolic rebalancing triggered systems-level adjustments in the transcriptome and proteome and in cellular traits, including increased growth and chronological lifespan but decreased resistance to oxidative stress. Thus, low Pyk1 activity does not lead to a growth advantage but to stress tolerance. The genetic tuning of glycolytic flux may reflect an adaptive trade-off in a species lacking pyruvate kinase isoforms.
20 Feb 2020
TL;DR: In the present study, a small marine-derived natural products library was assessed for antibacterial potential and in vitro validation and in silico binding mode studies revealed that 5-Tris could act as a dual enzyme inhibitor, indicating that the bromine position plays a crucial role in the determination of the antibacterial lead compound inhibitory activity.
Abstract: In the present study, a small marine-derived natural products library was assessed for antibacterial potential. Among 36 isolated compounds, a number of bis-indole derivatives exhibited growth-inhibitory activity towards Gram-positive strains (Bacillus subtilis and multidrug-resistant Staphylococcus aureus). 5- and 6-trisindoline (5-Tris and 6-Tris) were the most active derivatives (minimum inhibitory concentration, MIC, 4-8 µM) that were subsequently selected for anti-biofilm activity evaluation. Only 5-Tris was able to inhibit the staphylococcal biofilm formation starting at a 5 µM concentration. In order to investigate their possible molecular targets, both natural products were subjected to in silico inverse virtual screening. Among 20 target proteins, DNA gyrase and pyruvate kinase were the most likely to be involved in the observed antibacterial and anti-biofilm activities of both selected natural products. The in vitro validation and in silico binding mode studies revealed that 5-Tris could act as a dual enzyme inhibitor (IC50 11.4 ± 0.03 and 6.6 ± 0.05 µM, respectively), while 6-Tris was a low micromolar gyrase-B inhibitor (IC50 2.1 ± 0.08 µM), indicating that the bromine position plays a crucial role in the determination of the antibacterial lead compound inhibitory activity.