Tyrosine phosphorylation inhibits PKM2 to promote the Warburg effect and tumor growth

Post-translational modifications and the reprogramming of tumor metabolism

Metabolic reprogramming occurs alongside tumor development. As cancers advance from precancerous lesions to locally invasive tumors and then to metastatic tumors, metabolic patterns exhibit distinct changes, including mutations in metabolic enzymes and modifications in the activity of metabolic regulatory proteins. Alterations in metabolic patterns can influence tumor evolution, either establishing or alleviating metabolic burdens and facilitating cancer growth. To fully understand how metabolic reprogramming helps tumors grow and find the metabolic activities that are most useful for treating tumors, we need to have a deeper understanding of how metabolic patterns are controlled as tumors grow. Post-translational modifications (PTMs), a critical mechanism in the regulation of protein function, can influence protein activity, stability, and interactions in several ways. In tumor cells, PTMs-mediated metabolic reprogramming is a crucial mechanism for adapting to the challenging microenvironment and sustaining fast growth. This article will deeply explore the intricate regulatory mechanism of PTMs on metabolic reprogramming and its role in tumor progression, with the expectation of providing new theoretical basis and potential targets for tumor treatment.

Research trends on lactate in cancer: a bibliometric analysis and comprehensive review (2015-2024)

Objective

A bibliometric approach was employed to systematically analyze the trends and potential future developments in lactic acid-related cancer research over the past 10 years.

Method

We conducted a bibliometric analysis of literature on lactic acid in cancer research from 2015 to 2024, using data collected from the Web of Science database. A bibliometric analysis was conducted to identify general research directions and trends in current publications, as well as to determine the most prolific and influential authors, institutions, countries, and keywords in lactate and cancer research. The data were collected and analyzed using VOSviewer (Leiden University, Leiden, Netherlands), Microsoft Excel (Microsoft, Redmond, Washington, USA), CiteSpace, and Biblioshiny, with a focus on analysis and visualization.

Results

A total of 5,999 publications were analyzed, focusing on various aspects of the relevant literature, including year of publication, country, institution, author, journal, category, keywords, and research frontiers. The analysis of these publications reveals a general upward trend in publication volume from 2015 to 2024, with China and University of California System emerging as the most prolific country and institution, respectively. SCIENTIFIC REPORTS is the most frequently published journal, while Oncotarget is the most cited journal in the field. Zhang Y. was the most prolific author, publishing 100 documents over 10 years, with the highest citation count and an H-index of 28.Keyword analysis revealed five key themes in lactate-cancer research (2013-2023): Metabolic-epigenetic crosstalk, Tumor immunosuppressive microenvironment, Innovative therapies/drug delivery, Lactate-mediated signaling, Metabolic-targeted treatment strategies. Current research emphasizes the application of lactic acid metabolism in metabolic intervention, immune microenvironment regulation, combination of new therapeutic techniques and applications in specific cancer types.

Conclusion

Research on lactic acid in cancer is growing rapidly, with China at the forefront of this field. Research into lactic acid's role in immune cell regulation, metabolism, and signaling pathways, combined with multi-modal imaging, big data analytics, and innovative drug delivery, is set to become a key trend in future studies, which promises new directions for identifying therapeutic targets, biomarkers, and developing advanced treatments.

Centromere Protein F in Tumor Biology: Cancer's Achilles Heel

BACKGROUND

Centromere protein F (CENP-F) is an important nuclear matrix protein that regulates mitosis and the cell cycle, and plays a crucial role in recruiting spindle checkpoint proteins to maintain the accuracy of chromosome segregation. Studies have shown that CENP-F is closely involved in the pathogenesis of various diseases, particularly in the development and progression of malignant tumors, where it exhibits significant oncogenic activity.

OBJECTIVE

This review aims to systematically summarize the molecular structure, subcellular localization, expression regulation, intracellular transport mechanisms, biological functions, and carcinogenic mechanisms of CENP-F, as well as explore its potential value in cancer diagnosis and therapy.

METHODS

A comprehensive review and analysis of domestic and international research literature related to CENP-F were conducted, focusing on its role in tumorigenesis, development, and as a therapeutic target.

RESULTS

CENP-F acts as an oncogene and can maintain or promote the malignant phenotype of tumor cells through multiple mechanisms, including regulating signaling pathways related to cell proliferation and apoptosis, promoting metabolic reprogramming, angiogenesis, and tumor cell invasion and metastasis. Additionally, it plays an important role in the immune microenvironment and drug resistance regulation.

CONCLUSION

CENP-F plays a key, multidimensional role in tumor biology and is a promising therapeutic target for cancer treatment. Further exploration of the core pathways through which CENP-F regulates tumorigenesis and its potential for clinical translation is needed.

CD44-mediated metabolic rewiring is a targetable dependency of IDH-mutant leukemia

ABSTRACT

Recurrent isocitrate dehydrogenase (IDH) mutations catalyze nicotinamide adenine dinucleotide phosphate (NADPH)-dependent production of oncometabolite (R)-2-hydroxyglutarate (R-2HG) for tumorigenesis. IDH inhibition provides clinical response in a subset of acute myeloid leukemia (AML) cases; however, most patients develop resistance, highlighting the need for more effective IDH-targeting therapies. By comparing transcriptomic alterations in isogenic leukemia cells harboring CRISPR base-edited IDH mutations, we identify the activation of adhesion molecules including CD44, a transmembrane glycoprotein, as a shared feature of IDH-mutant leukemia, consistent with elevated CD44 expression in IDH-mutant AML patients. CD44 is indispensable for IDH-mutant leukemia cells through activating pentose phosphate pathway and inhibiting glycolysis by phosphorylating glucose-6-phosphate dehydrogenase and pyruvate kinase muscle isozyme M2, respectively. This metabolic rewiring ensures efficient NADPH generation for mutant IDH-catalyzed R-2HG production. Combining IDH inhibition with CD44 blockade enhances the elimination of IDH-mutant leukemia cells. Hence, we describe an oncogenic feedforward pathway involving CD44-mediated metabolic rewiring for oncometabolite production, representing a potentially targetable dependency of IDH-mutant malignancies.

PKM2 crotonylation reprograms glycolysis in VSMCs, contributing to phenotypic switching

Post-translational modifications (PTMs) of pyruvate kinase M2 (PKM2) play a vital role in regulating its activity and function. Recently, we found PKM2 can undergo crotonylation in vascular smooth muscle cell (VSMC) phenotypic switching. However, the role of PKM2 crotonylation remains unknown. Here, we verify a crucial role of PKM2 crotonylation in VSMC metabolic reprogramming. In PDGF-BB-induced synthetic VSMCs, PKM2 crotonylation was upregulated and promotes its nuclear translocation, thereby facilitating the expression of Glut1 and Ldha. Furthermore, crotonylation facilitated the dimeric formation of PKM2. Then we identified the highly conserved crotonylation site at K305 across different species. The crotonylation of PKM2 was compromised by PKM2 K305 mutation, resulting in the suppression of PKM2 dimeric configuration and nuclear relocation, and ultimately reducing glycolysis rate. Furthermore, PKM2 K305 crotonylation was necessary for VSMC phenotypic switching in vitro and intimal hyperplasia in vivo via infection of PKM2 recombinant adenovirus. In summary, PKM2 K305 crotonylation facilitates VSMC aerobic glycolysis by enhancing PKM2 dimeric form.

Impact of Cancer-Associated PKM2 Mutations on Enzyme Activity and Allosteric Regulation: Structural and Functional Insights into Metabolic Reprogramming

Mammalian pyruvate kinase M2 (PKM2) is a key regulator of glycolysis and is highly expressed in proliferative tissues including tumors. Mutations in PKM2 have been identified in various cancers, but their effects on enzyme activity and regulation are not fully understood. This study investigates the structural and functional effects of cancer-associated PKM2 mutations on enzyme kinetics, allosteric regulation, and oligomerization. Using computational modeling, X-ray crystallography, and biochemical assays, we demonstrated how these mutations impact PKM2 activity, substrate binding, and allosteric activation via fructose-1,6-bisphosphate (FBP), contributing to altered enzyme function. In this study, we characterized four cancer-associated PKM2 mutations (P403A, C474S, R516C, and L144P) using computational, structural, and biochemical approaches. Computational modeling revealed disruptions in allosteric signaling pathways, particularly affecting the communication between regulatory sites and the active site. X-ray crystallography demonstrated local conformational changes in the hinge and FBP-binding regions, leading to a shift from the active tetrameric state to a less active dimeric state, particularly in the C474S and R516C mutants. The mutants exhibited reduced maximal velocity, reduced substrate affinity, and altered activation by the allosteric activator fructose-1,6-bisphosphate (FBP). Under alkaline pH conditions, mimicking the tumor microenvironment, these mutations further destabilized the PKM2 oligomeric state, favoring the formation of lower-order species. Our findings suggest that PKM2 is highly sensitive to mutations, and these alterations may contribute to metabolic reprogramming in cancer cells by impairing its enzymatic regulation.

PKM splice-switching ASOs induce upregulation of dual-specificity phosphatases and dephosphorylation of ERK1/2 in hepatocellular carcinoma

Pyruvate kinase muscle isoform 2 (PKM2) is preferentially expressed in nearly all cancers. It primarily functions as the last enzyme in glycolysis but has other reported noncanonical functions, including recruiting transcription factors to oncogenes and phosphorylating proteins. We previously described antisense oligonucleotides that disrupt alternative splicing of PKM pre-mRNA (PKM-ASOs), resulting in a PKM2-to-PKM1 isoform switch in hepatocellular carcinoma (HCC), which reduces HCC growth in vitro and in vivo. PKM1 has higher enzymatic activity than PKM2, which potentially drives metabolism away from macromolecule synthesis, and may explain decreased HCC growth upon PKM-ASO treatment. As PKM-ASOs also reduce PKM2 levels, how PKM splice-switching inhibits HCC cell proliferation was unclear. Here, we characterized the individual consequences of altering PKM1 or PKM2 protein levels in HCC and observed that reducing PKM2 alone was sufficient to decrease HCC cell proliferation, whereas overexpressing PKM1 had no effect. Moreover, increasing PK activity via a small-molecule PKM2 activator had no effect on HCC cell proliferation, suggesting that PKM-ASOs affect PKM2's nonmetabolic functions. Transcriptomic and RT-qPCR analyses of HCC cells treated with PKM-ASO or PKM2-siRNA revealed upregulation of dual-specificity phosphatase 2 (DUSP2) and other related DUSPs, which act directly on ERK1/2 in the MAPK signaling pathway. Luciferase reporter assays demonstrated that PKM-ASO treatment activated the DUSP2 promoter, which correlated with decreased ERK1/2 phosphorylation. Lenvatinib is a second-line HCC therapy that indirectly reduces ERK1/2 phosphorylation, and combined treatment with PKM-ASOs inhibited proliferation of HCC cells more than either treatment alone. In summary, our results reveal a mechanism by which PKM-ASOs affect PKM2 dependency in HCC.

Macrophage junctional adhesion molecule-like (JAML) protein promotes NLRP3 inflammasome activation in the development of atherosclerosis

Inflammation plays a crucial role in the progression of atherosclerosis. Junctional adhesion molecule-like protein (JAML), a type-I transmembrane glycoprotein, activates downstream signaling pathways. However, the precise role of macrophage-derived JAML in inflammation and atherosclerosis remains unclear. This study aimed to generate mice with macrophage-specific deletion or overexpression of JAML, with the focus of assessing its impact on macrophage function and elucidating its regulatory mechanism in atherosclerosis. High-throughput data screening was employed to investigate JAML expression in atherosclerosis, and macrophage-specific JAML-knockout and transgenic mice models were utilized to examine the effects of JAML on atherosclerosis. Furthermore, the role of JAML was assessed using Oil Red O staining, RNA-sequencing analysis, and co-immunoprecipitation techniques. Increased JAML expression was observed in macrophages from both mice and patients with atherosclerosis. Macrophage-specific JAML deletion attenuated atherosclerosis and inflammation, whereas macrophage-specific JAML overexpression exacerbated these conditions. Mechanistically, JAML deletion inhibited inflammation by decreasing nuclear translocation of pyruvate kinase M2 (PKM2) and PKM2/p65 complex formation, which consequently suppressed the nuclear factor kappa B (NF-κB) pathway and NLRP3 inflammasome activation. Taken together, these findings demonstrate that macrophage-expressed JAML facilitates the progression of atherosclerosis by activating the NF-κB pathway and NLRP3 inflammasome through nuclear migration and phosphorylation of PKM2. Notably, our study revealed a novel mechanism for the regulation of NLRP3 inflammasome activation in atherosclerosis. Therefore, targeting JAML may be an effective treatment strategy for atherosclerosis, a condition characterized by chronic inflammation.

SIRT3-PINK1-PKM2 axis prevents osteoarthritis via mitochondrial renewal and metabolic switch

Maintaining mitochondrial homeostasis is critical for preserving chondrocyte physiological conditions and increasing resistance against osteoarthritis (OA). However, the underlying mechanisms governing mitochondrial self-renewal and energy production remain elusive. In this study, we demonstrated mitochondrial damage and aberrant mitophagy in OA chondrocytes. Genetically overexpressing PTEN-induced putative kinase 1 (PINK1) protects against cartilage degeneration by removing defective mitochondria. PINK1 knockout aggravated cartilage damage due to impaired mitophagy. SIRT3 directly deacetylated PINK1 to promote mitophagy and cartilage anabolism. Specifically, PINK1 phosphorylated PKM2 at the Ser127 site, preserving its active tetrameric form. This inhibited nuclear translocation and the interaction with β-catenin, resulting in a metabolic shift and increased energy production. Finally, a double-knockout mouse model demonstrated the role of the SIRT3-PINK1-PKM2 axis in safeguarding the structural integrity of articular joints and improving motor functions. Overall, this study provides a novel insight into the regulation of mitochondrial renewal and metabolic switches in OA.

NONO interacts with nuclear PKM2 and directs histone H3 phosphorylation to promote triple-negative breast cancer metastasis

BACKGROUND

Emerging evidence has revealed that PKM2 has oncogenic functions independent of its canonical pyruvate kinase activity, serving as a protein kinase that regulates gene expression. However, the mechanism by which PKM2, as a histone kinase, regulates the transcription of genes involved in triple-negative breast cancer (TNBC) metastasis remains poorly understood.

METHODS

We integrated cellular analysis, including cell viability, proliferation, colony formation, and migration assays; biochemical assays, including protein interaction studies and ChIP; clinical sample analysis; RNA-Seq and CUT&Tag data; and xenograft or mammary-specific gene knockout mouse models, to investigate the epigenetic modulation of TNBC metastasis via NONO-dependent interactions with nuclear PKM2.

RESULTS

We report that the transcription factor NONO directly interacts with nuclear PKM2 and directs PKM2-mediated phosphorylation of histone H3 at threonine 11 (H3T11ph) to promote TNBC metastasis. We show that H3T11ph cooperates with TIP60-mediated acetylation of histone H3 at lysine 27 (H3K27ac) to activate SERPINE1 expression and to increase the proliferative, migratory, and invasive abilities of TNBC cells in a NONO-dependent manner. Conditional mammary loss of NONO or PKM2 markedly suppressed SERPINE1 expression and attenuated the malignant progression of spontaneous mammary tumors in mice. Importantly, elevated expression of NONO or PKM2 in TNBC patients is positively correlated with SERPINE1 expression, enhanced invasiveness, and poor clinical outcomes.

CONCLUSION

These findings revealed that the NONO-dependent interaction with nuclear PKM2 is key for the epigenetic modulation of TNBC metastasis, suggesting a novel intervention strategy for treating TNBC.

Progress of Pyruvate Kinase M2 in Hepatocellular Carcinoma-Associated Signaling Pathway

Hepatocellular carcinoma (HCC) is an aggressive liver tumor with a unique metabolic profile and a shift to glycolytic metabolism. This review discusses the contribution of pyruvate kinase M2 (PKM2) to HCC development and its potential as a target for therapy. We carried out a broad literature review on PKM2, focusing on its role in the glycolytic pathway and special interactions with key signaling pathways like Phosphoinositide 3-kinase/Protein kinase B/Mammalian target of rapamycin (PI3K/AKT/mTOR) and Mitogen-activated protein kinase (MAPK). PKM2 also performs a dual role in energy metabolism and signal transduction in HCC. PKM2 is paramount in the induction of HCC by regulating cellular metabolism and oncogenic signaling pathways. It promotes tumor growth, survival, and metastasis through interaction with the PI3K/AKT/mTOR and MAPK pathways. PKM2 is a key factor in HCC pathogenesis, with a dual impact on metabolism and signaling. Its properties may open the way for developing novel therapeutic interventions against HCC. Thus, PKM2 inhibition may offer further opportunities for tumor growth blockade, which could meaningfully improve patients' clinical outcomes.

CADD-based discovery of novel oligomeric modulators of PKM2 with antitumor activity in aggressive human glioblastoma models

Pyruvate kinase isoform M2 (PKM2) is a multifunctional enzyme capable of transitioning between monomeric, dimeric, and tetrameric states, with its oligomeric equilibrium playing a pivotal role in tumour progression and survival. The unique exon ten at the dimer-dimer interface represents an attractive target for isoform-specific modulation, offering opportunities for disrupting this equilibrium and altering tumour cell dynamics. This study identifies a novel druggable pocket at the PKM2 dimer interface through conformational analysis. This pocket was exploited in a virtual screening of a large small-molecule library, identifying two promising candidates, C599 and C998. Both compounds exhibited dose-dependent antiproliferative effects in glioblastoma cell lines and induced apoptosis, as evidenced by caspase 3/7 activation. These effects were directly linked to their inhibition of PKM2 enzymatic activity, validating the proposed mechanism of action in their rational design. ADMET studies further highlighted their strong potential as lead PKM2 inhibitors for GBM treatment. Molecular dynamics (MD) simulations and post-MD analyses, including Dynamic Cross-Correlation Maps (DCCM), Probability Density Function (PDF), and Free Energy Landscape (FEL), confirmed the stability of the protein-ligand interactions and highlighted critical residues at the dimer-dimer interface. The Steered MD simulations demonstrated the high affinity of the compounds for PKM2, as evidenced by the requirement of high rupture forces to induce an unbinding event. These results highlight the potential of the compounds as oligomeric modulators of PKM2. These findings position C599 and C998 as promising lead compounds for antitumor applications. Future studies will focus on optimising these candidates and assessing their efficacy in vivo glioblastoma models, reassuring the thoroughness of our research and the potential for further advancements.

Coptisine improves LPS-induced anxiety-like behaviors by regulating the Warburg effect in microglia via PKM2

Neuroinflammation mediated by microglia is considered the primary cause and pathological process of anxiety. Abnormal glycolysis of microglia is observed during microglia activation. However, whether regulating the Warburg effect in microglia can effectively intervene anxiety and its potential mechanisms have not been elucidated. This study focused on coptisine (Cop), a natural alkaloid that regulates the glycolysis and function of microglia affecting anxiety. The effects of Cop on anxiety-like behaviors, hippocampal synaptic function, and excessive activation of microglia were assessed in lipopolysaccharide (LPS) induced mouse models of anxiety. Microglia expressing mutant pyruvate kinase isoform M2 (PKM2) were used to further investigate the molecular mechanism by which Cop regulates the phenotype of microglia. neuroinflammatory is emerging Further research revealed that Cop attaches to the amino acid residue phenylalanine 26 of PKM2, shifting the dynamic equilibrium of PKM2 towards tetramers, and enhancing its pyruvate kinase activity. This interaction prevented LPS-induced Warburg effect and inactivated PKM2/hypoxia-inducible factor-1α (HIF-1α) pathway in microglia. In conclusion, Cop attenuates anxiety by regulating the Warburg effect in microglia. Our work revealed the role of PKM2/(HIF-1α) pathway in anxiety for the first time. Importantly, the molecular mechanism by which Cop ameliorates anxiety-like behaviors is through modulation of the dimeric/tetrameric form of PKM2, indicating the usefulness of PKM2 as a key potential target for the treatment of anxiety.

Targeting Metabolic Vulnerabilities to Combat Drug Resistance in Cancer Therapy

Drug resistance remains a significant barrier to effective cancer therapy. Cancer cells evade treatment by reprogramming their metabolism, switching from glycolysis to oxidative phosphorylation (OXPHOS), and relying on alternative carbon sources such as glutamine. These adaptations not only enable tumor survival but also contribute to immune evasion through mechanisms such as reactive oxygen species (ROS) generation and the upregulation of immune checkpoint molecules like PD-L1. This review explores the potential of targeting metabolic weaknesses in drug-resistant cancers to enhance therapeutic efficacy. Key metabolic pathways involved in resistance, including glycolysis, glutamine metabolism, and the kynurenine pathway, are discussed. The combination of metabolic inhibitors with immune checkpoint inhibitors (ICIs), particularly anti-PD-1/PD-L1 therapies, represents a promising approach to overcoming both metabolic and immune evasion mechanisms. Clinical trials combining metabolic and immune therapies have shown early promise, but further research is needed to optimize treatment combinations and identify biomarkers for patient selection. In conclusion, targeting cancer metabolism in combination with immune checkpoint blockade offers a novel approach to overcoming drug resistance, providing a potential pathway to improved outcomes in cancer therapy. Future directions include personalized treatments based on tumor metabolic profiles and expanding research to other tumor types.

Chemical looping synthesis of amines from N2 via iron nitride as a mediator

Amines are commonly synthesized through the amination of organooxygenates using ammonia, frequently involving the use of noble metal catalysts. In this study, we present an alternative route to make amines using iron nitride (Fe2.5N) as the nitrogen source. Without any additional catalyst, Fe2.5N reacts with a range of alcohols at 250 °C under 1 or 10 bar H2 to produce amines as major products. Mechanistic investigations indicate that hydrogen activates the nitrogen species within iron nitride, converting them into surface NH and NH2 groups that then react with alcohols to form amines. Building on this foundation, we further demonstrate an iron nitride-mediated chemical looping pathway that utilizes N2 as the nitrogen source to synthesize octylamines. In this process, N2 first reacts with iron to form FexN by a ball-milling method at ambient temperature and 6 bar N2. The as-prepared FexN subsequently reacts with alcohols to yield amines, transferring over 80% of the nitrogen to organic compounds. This looping process proves stable across four cycles.

PFKFB3-dependent redox homeostasis and DNA repair support cell survival under EGFR-TKIs in non-small cell lung carcinoma

BACKGROUND

The efficacy of tyrosine kinase inhibitors (TKIs) targeting the EGFR is limited due to the persistence of drug-tolerant cell populations, leading to therapy resistance. Non-genetic mechanisms, such as metabolic rewiring, play a significant role in driving lung cancer cells into the drug-tolerant state, allowing them to persist under continuous drug treatment.

METHODS

Our study employed a comprehensive approach to examine the impact of the glycolytic regulator 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3) on the adaptivity of lung cancer cells to EGFR TKI therapies. We conducted metabolomics to trace glucose rerouting in response to PFKFB3 inhibition during TKI treatment. Live cell imaging and DCFDA oxidation were used to quantify levels of oxidation stress. Immunocytochemistry and Neutral Comet assay were employed to evaluate DNA integrity in response to therapy-driven oxidative stress.

RESULTS

Our metabolic profiling revealed that PFKFB3 inhibition significantly alters the metabolic profile of TKI-treated cells. It limited glucose utilization in the polyol pathway, glycolysis, and TCA cycle, leading to a depletion of ATP levels. Furthermore, pharmacological inhibition of PFKFB3 overcome TKI-driven redox capacity by diminishing the expression of glutathione peroxidase 4 (GPX4), thereby exacerbating oxidative stress. Our study also unveiled a novel role of PFKFB3 in DNA oxidation and damage by controlling the expression of DNA-glycosylases involved in base excision repair. Consequently, PFKFB3 inhibition improved the cytotoxicity of EGFR-TKIs by facilitating ROS-dependent cell death.

CONCLUSIONS

Our results suggest that PFKFB3 inhibition reduces glucose utilization and DNA damage repair, limiting the adaptivity of the cells to therapy-driven oxidative stress and DNA integrity insults. Inhibiting PFKFB3 can be an effective strategy to eradicate cancer cells surviving under EGFR TKI therapy before they enter the drug-resistant state. These findings may have potential implications in the development of new therapies for drug-resistant cancer treatment.

Treponema Pallidum protein Tp47 triggers macrophage inflammatory senescence via PKM2-mediated metabolic reprogramming

Syphilis is a sexually transmitted disease caused by Treponema pallidum. The mechanisms enabling T. pallidum to persist despite macrophage eradication efforts in syphilis remain unclear. Pathogens can exploit senescent cells to enhance host susceptibility, and cellular senescence can be induced by pyroptosis, which known as inflammatory senescence. While recent studies have linked metabolic reprogramming to inflammatory senescence, their role in syphilis remained to be clarified. This study investigated the mechanisms of Tp47 on metabolic reprogramming and inflammatory senescence in macrophages. The results demonstrated that Tp47 triggered NLRP3 inflammasome-mediated pyroptosis by activating the phosphorylation of EIF2AK2 (a protein kinase), increasing senescence-associated pro-inflammatory cytokines secretion and leading to inflammatory senescence in macrophages. Additionally, Tp47 competitively bound to pyruvate kinase M2 (PKM2) with STUB1(a ubiquitin ligase), thereby inhibiting PKM2 ubiquitination degradation. By promoting the Y105 phosphorylation of PKM2, Tp47 modulated the intracellular function of PKM2, and facilitated PKM2-mediated metabolic reprogramming, which produced lactate that subsequently led to EIF2AK2 phosphorylation. Furthermore, inhibitors targeting EIF2AK2, lactate, glycolysis, and PKM2 effectively suppressed the inflammatory senescence induced by Tp47. In conclusion, Tp47 could mediate immune metabolic reprogramming through interaction with PKM2 to trigger macrophage inflammatory senescence. These discoveries offer a novel perspective for targeted therapies against syphilis.

Inhibition of LDHB suppresses the metastatic potential of lung cancer by reducing mitochondrial GSH catabolism

Metastasis, the leading cause of cancer death, is closely linked to lactate metabolism. Our study aimed to investigate the role of lactate dehydrogenase B (LDHB), which mainly catalyzes the conversion of lactate to pyruvate, in the metastatic potential of lung cancer. We found that LDHB silencing reduced the invasion and migration ability of lung cancer cells in vitro. On the molecular level, LDHB silencing decreased the total intracellular levels of the antioxidant glutathione (GSH). Surprisingly, LDHB silencing did not increase cellular or mitochondrial reactive oxygen species (ROS) levels. Furthermore, supplementation with GSH monoethyl ester (GSH-mee), a cell-permeable derivative of GSH, partially restored the reduced in vitro colony formation capacity, the oxygen consumption rate, and the invasion and migration capacity of lung cancer cells after LDHB silencing. Using metabolic inhibitors, we showed that the rescue of colony formation after silencing LDHB by GSH-mee was due to enhanced GSH catabolism by γ-L-Glutamyl transpeptidase (GGT), which was mainly present in the mitochondrial fraction of lung cancer cells. Furthermore, we observed that high GGT expression was a prerequisite for the rescue of migratory capacity by GSH-mee after LDHB silencing. Finally, our in vivo experiments demonstrated that targeting LDHB reduced the metastasis of human and mouse lung cancer cells in immunodeficient and immunocompetent mouse models, respectively. In conclusion, LDHB silencing decreases GSH catabolism mediated by GGT, which is primarily located in the mitochondria of cancer cells. Therefore, targeting LDHB is a promising therapeutic approach for the prevention and treatment of metastatic lung cancer.

Parallel phosphoproteomics and metabolomics map the global metabolic tyrosine phosphoproteome

Tyrosine phosphorylation of metabolic enzymes is an evolutionarily conserved posttranslational modification that facilitates rapid and reversible modulation of enzyme activity, localization, or function. Despite the high abundance of tyrosine phosphorylation events detected on metabolic enzymes in high-throughput mass spectrometry-based studies, functional characterization of tyrosine phosphorylation sites has been limited to a subset of enzymes. Since tyrosine phosphorylation is dysregulated across human diseases, including cancer, understanding the consequences of metabolic enzyme tyrosine phosphorylation events is critical for informing disease biology and therapeutic interventions. To globally identify metabolic enzyme tyrosine phosphorylation events and simultaneously assign functional significance to these sites, we performed parallel phosphoproteomics and polar metabolomics in nontumorigenic mammary epithelial cells (MCF10A) stimulated with epidermal growth factor (EGF) in the absence or presence of the EGF receptor inhibitor erlotinib. We performed an integrated analysis of the phosphoproteomic and metabolomic datasets to identify tyrosine phosphorylation sites on metabolic enzymes with functional consequences. We identified two previously characterized (pyruvate kinase muscle isozyme, phosphoglycerate mutase 1) and two uncharacterized (glutathione S-transferase Pi 1, glutamate dehydrogenase 1) tyrosine phosphorylation sites on metabolic enzymes with purported functions based on metabolomic analyses. We validated these hits using a doxycycline-inducible CRISPR interference system in MCF10A cells, in which target metabolic enzymes were depleted with simultaneous reexpression of wild-type, phosphomutant, or phosphomimetic isoforms. Together, these data provide a framework for identification, prioritization, and characterization of tyrosine phosphorylation sites on metabolic enzymes with functional significance.

Interplay of CDKs and cyclins with glycolytic regulatory enzymes PFK and PK

In plants, as in all eukaryotes, the cell cycle is regulated by the heterodimer formed by cyclins (Cycs) and cyclin-dependent kinases (CDKs), that phosphorylate serine/threonine residues in target proteins. The extensive involvement of these heterodimers in nuclear cell cycle-related processes has been demonstrated. However, recent findings have linked Cyc-CDK complexes to the regulation of cytosolic processes, including various metabolic pathways, suggesting close coordination between the cell cycle and catabolic/anabolic processes to maintain cellular energy homeostasis. This study extends the analysis of Cyc-CDK complex regulation in maize to two key regulators of glycolysis: phosphofructose kinase (PFK) and pyruvate kinase (PK). Both are cytosolic enzymes, highly regulated positively and negatively by different metabolites, showing a similar activation pattern in their homotetrameric form and low activity when as dimers/monomers. Each enzyme exhibits two putative minimal phosphorylation motives for Cyc-CDKs, conserved in some plant species and in four (PFK) and three (PK) isoforms in maize. This work demonstrates that both enzymes are active with fluctuating levels of activity along maize germination; also, that they associate with different maize Cycs and CDKs as demonstrated by pull-down assays, as well as their in vitro phosphorylation by recombinant CycD;2-CDKA or CycD2;2-CDKB complexes. Additionally, the inhibition of PFK and PK activity following phosphorylation by active Cycs-CDKB complexes obtained by immunoprecipitation from imbibed embryonic axis protein extracts suggests a narrow and negative regulation of glycolysis as the cell cycle progresses. A decreased carbon flow through this pathway is proposed to divert carbon from sugars towards the oxidative pentose phosphate pathway, thereby promoting de novo nucleic acid synthesis precursors to stimulate cell cycle progression.

CHAC1 blockade suppresses progression of lung adenocarcinoma by interfering with glucose metabolism via hijacking PKM2 nuclear translocation

Patients with lung adenocarcinoma (LUAD) generally have poor prognosis. Abnormal cellular energy metabolism is a hallmark of LUAD. Glutathione-specific gamma-glutamylcyclotransferase 1 (CHAC1) is a member of the γ-glutamylcyclotransferase family and an unfolded protein response pathway regulatory gene. Its biological function and molecular regulatory mechanism, especially regarding energy metabolism underlying LUAD, remain unclear. By utilizing tissue microarray and data from The Cancer Genome Atlas and Gene Expression Omnibus, we found that CHAC1 expression was markedly higher in LUAD tissues than in non-tumor tissues, and was positively correlated with poor prognosis. Phenotypically, CHAC1 overexpression enhanced the proliferation, migration, invasion, tumor sphere formation, and glycolysis ability of LUAD cells, resulting in tumor growth both in vitro and in vivo. Mechanistically, through a shotgun mass spectrometry-based proteomic approach and high-throughput RNA sequencing, we found that CHAC1 acted as a bridge connecting UBA2 and PKM2, enhancing the SUMOylation of PKM2. The SUMOylated PKM2 then transferred from the cytoplasm to the nucleus, activating the expression of glycolysis-related genes and enhancing the Warburg effect. Lastly, E2F Transcription Factor 1 potently activated CHAC1 transcription by directly binding to the CHAC1 promoter in LUAD cells. The results of this study implied that CHAC1 regulates energy metabolism and promotes glycolysis in LUAD progression.

Age-Related Changes in the Glycolytic Enzymes of M2-Isoform of Pyruvate Kinase and Fructose-1,6-Bisphosphate Aldolase: Implications to Age-Related Macular Degeneration

Prior studies have emphasized a bioenergetic crisis in the retinal pigment epithelium (RPE) as a critical factor in the development of age-related macular degeneration (AMD). The isoforms Fructose-1,6-bisphosphate aldolase C (ALDOC) and pyruvate kinase M2 (PKM2) have been proposed to play a role in AMD pathogenesis. While PKM2 and ALDOC are crucial for aerobic glycolysis in the neural retina, they are not as essential for the RPE. In this study, we examined the expression and activity of PKM2 and ALDOC in both young and aged RPE cells, as well as in the retina and RPE tissue of mice, including an experimentally induced AMD mouse model. Our findings reveal an upregulation in PKM2 and ALDOC expression, accompanied by increased pyruvate kinase activity, in the aged and AMD mouse RPE. Conversely, there is a decrease in ALDOC expression but an increase in PKM2 expression and pyruvate kinase activity in the aged and AMD retina. Overall, our study indicates that aged and AMD RPE cells tend to favor aerobic glycolysis, while this tendency is diminished in the aged and AMD retina. These results underscore the significance of targeting PKM2 and ALDOC in the RPE as a promising therapeutic approach to address the bioenergetic crisis and prevent vision loss in AMD.

Reduced bioenergetics and mitochondrial fragmentation in human primary cytotrophoblasts induced by an EGFR-targeting chemical mixture

Exposures to complex environmental chemical mixtures during pregnancy reach and target the feto-placental unit. This study investigates the influence of environmental chemical mixtures on placental bioenergetics. Recognizing the essential role of the epidermal growth factor receptor (EGFR) in placental development and its role in stimulating glycolysis and mitochondrial respiration in trophoblast cells, we explored the effects of chemicals known to disrupt EGFR signaling on cellular energy production. Human primary cytotrophoblasts (hCTBs) and a first-trimester extravillous trophoblast cell line (HTR-8/SVneo) were exposed to a mixture of EGFR-interfering chemicals, including atrazine, bisphenol S, niclosamide, PCB-126, PCB-153, and trans-nonachlor. An RNA sequencing approach revealed that the mixture altered the transcriptional signature of genes involved in cellular energetics. Next, the impact of the mixture on cellular bioenergetics was evaluated using a combination of mitochondrial and glycolytic stress tests, ATP production, glucose consumption, lactate synthesis, and super-resolution imaging. The chemical mixture did not alter basal oxygen consumption but diminished the maximum respiratory capacity in a dose-dependent manner, indicating a disruption of mitochondrial function. The respiratory capacity and ATP production were increased by EGF, while the Chem-Mix reduced both EGF- and non-EGF-mediated oxygen consumption rate in hCTBs. A similar pattern was observed in the glycolytic medium acidification, with EGF increasing the acidification, and the Chem-Mix blocking EGF-induced glycolytic acidification. Furthermore, direct stochastic optical reconstruction microscopy (dSTORM) imaging demonstrated that the Chem-Mix led to a reduction of the mitochondrial network architecture, with findings supported by a decrease in the abundance of OPA1, a mitochondrial membrane GTPase involved in mitochondrial fusion. In conclusion, we demonstrated that a mixture of EGFR-disrupting chemicals alters mitochondrial remodeling, resulting in disturbed cellular bioenergetics, reducing the capacity of human cytotrophoblast cells to generate energy. Future studies should investigate the mechanism by which mitochondrial dynamics are disrupted and the pathological significance of these findings.

Inhibition of KIAA1429/HK1 axis enhances the sensitivity of liver cancer cells to sorafenib by regulating the Warburg effect

N6-methyladenosine (m6A) serves as the most abundant posttranscription modification. However, the role of m6A in tumorigenesis and chemotherapeutic drugs sensitivity remains largely unclear. Present research focuses on the potential function of the m6A writer KIAA1429 in tumor development and sorafenib sensitivity in liver cancer. We found that the level of KIAA1429 was significantly elevated in liver cancer tissues and cells and was closely associated with poorer prognosis. Functionally, KIAA1429 promoted the proliferation and Warburg effect of liver cancer cells in vitro and in vivo. RNA-seq and MeRIP-seq analysis revealed the glycolysis was one of the most affected pathways by KIAA1429, and m6A-modified HK1 was the most likely targeted gene to regulate the Warburg effect. KIAA1429 depletion decreased Warburg effect and increased sorafenib sensitivity in liver cancer. Mechanistically, KIAA1429 could affect the m6A level of HK1 mRNA through directly binding with it. Moreover, KIAA1429 cooperated with the m6A reader HuR to enhance HK1 mRNA stability, thereby upregulating its expression. These findings demonstrated that KIAA1429/HK1 axis decreases the sensitivity of liver cancer cells to sorafenib by regulating the Warburg effect, which may provide a novel therapeutic target for liver cancer treatment.

Deciphering the interaction between PKM2 and the built-in thermodynamic properties of the glycolytic pathway in cancer cells

Most cancer cells exhibit high glycolysis rates under conditions of abundant oxygen. Maintaining a stable glycolytic rate is critical for cancer cell growth as it ensures sufficient conversion of glucose carbons to energy, biosynthesis, and redox balance. Here we deciphered the interaction between PKM2 and the thermodynamic properties of the glycolytic pathway. Knocking down or knocking out PKM2 induced a thermodynamic equilibration in the glycolytic pathway, characterized by the reciprocal changes of the Gibbs free energy (ΔG) of the reactions catalyzed by PFK1 and PK, leading to a less exergonic PFK1-catalyzed reaction and a more exergonic PK-catalyzed reaction. The changes in the ΔGs of the two reactions cause the accumulation of intermediates, including the substrate PEP (the substrate of PK), in the segment between PFK1 and PK. The increased concentration of PEP in turn increased PK activity in the glycolytic pathway. Thus, the interaction between PKM2 and the thermodynamic properties of the glycolytic pathway maintains the reciprocal relationship between PK concentration and its substrate PEP concentration, by which, PK activity in the glycolytic pathway can be stabilized and effectively counteracts the effect of PKM2 KD or KO on glycolytic rate. In line with our previous reports, this study further validates the roles of the thermodynamics of the glycolytic pathway in stabilizing glycolysis in cancer cells. Deciphering the interaction between glycolytic enzymes and the thermodynamics of the glycolytic pathway will promote a better understanding of the flux control of glycolysis in cancer cells.

Systematic Review and Clinical Insights: The Role of the Ketogenic Diet in Managing Glioblastoma in Cancer Neuroscience

Recent scientific research has shown that the ketogenic diet may have potential benefits in a variety of medical fields, which has led to the diet receiving a substantial amount of attention. Clinical and experimental research on brain tumors has shown that the ketogenic diet has a satisfactory safety profile. This safety profile has been established in a variety of applications, including the management of obesity and the treatment of drug-resistant epileptic cases. However, in human studies, the impact of ketogenic therapy on the growth of tumors and the life expectancy of patients has not provided results that are well characterized. Consequently, our purpose is to improve the comprehension of these features by succinctly presenting the developments and conclusions that have been gained from the most recent study that pertains to this non-pharmacological technique. According to the findings of our study, patients with brain tumors who stick to a ketogenic diet are more likely to experience improved survival rates. However, it is required to conduct additional research on humans in order to more accurately define the anti-tumor efficiency of this diet as well as the underlying processes that support the therapeutic effects of this dieting regimen.

PDIA3 orchestrates effector T cell program by serving as a chaperone to facilitate the non-canonical nuclear import of STAT1 and PKM2

Dysregulated T cell activation underpins the immunopathology of rheumatoid arthritis (RA), yet the machineries that orchestrate T cell effector program remain incompletely understood. Herein, we leveraged bulk and single-cell RNA sequencing data from RA patients and validated protein disulfide isomerase family A member 3 (PDIA3) as a potential therapeutic target. PDIA3 is remarkably upregulated in pathogenic CD4 T cells derived from RA patients and positively correlates with C-reactive protein level and disease activity score 28. Pharmacological inhibition or genetic ablation of PDIA3 alleviates RA-associated articular pathology and autoimmune responses. Mechanistically, T cell receptor signaling triggers intracellular calcium flux to activate NFAT1, a process that is further potentiated by Wnt5a under RA settings. Activated NFAT1 then directly binds to the Pdia3 promoter to enhance the expression of PDIA3, which complexes with STAT1 or PKM2 to facilitate their nuclear import for transcribing T helper 1 (Th1) and Th17 lineage-related genes, respectively. This non-canonical regulatory mechanism likely occurs under pathological conditions, as PDIA3 could only be highly induced following aberrant external stimuli. Together, our data support that targeting PDIA3 is a vital strategy to mitigate autoimmune diseases, such as RA, in clinical settings.

MAPK/ERK-PK(Ser11) pathway regulates divergent thermal metabolism of two congeneric oyster species

Pyruvate kinase (PK), as a key rate-limiting enzyme in glycolysis, has been widely used to assess the stress tolerance and sensitivity of organisms. However, its phosphorylation regulatory mechanisms mainly focused on human cancer research, with no reports in marine organisms. In this study, we firstly reported a conserved PK Ser11 phosphorylation site in mollusks, which enhanced enzyme activity by promoting substrate binding, thereby regulating divergent thermal metabolism of two allopatric congeneric oyster species with differential habitat temperature. It was phosphorylated by ERK kinase, and regulated by the classical MAPK pathway. The MAPK/ERK-PK signaling cascade responded to increased environmental temperature and exhibited stronger activation pattern in the relatively thermotolerant species (Crassostrea angulata), indicating its involvement in shaping temperature adaptation. These findings highlight the presence of complex and unique phosphorylation-mediated signaling transduction mechanisms in marine organisms, and provide new insights into the evolution and function of the crosstalk between classical pathways.

The potential roles of PKM2 in cerebrovascular diseases

Pyruvate kinase M2 (PKM2), a key enzyme involved in glycolysis,plays an important role in regulating cell metabolism and growth under different physiological conditions. PKM2 has been intensively investigated in multiple cancer diseases. Recent years, many studies have found its pivotal role in cerebrovascular diseases (CeVDs), the disturbances in intracranial blood circulation. CeVDs has been confirmed to be closely associated with oxidative stress (OS), mitochondrial dynamics, systemic inflammation, and local neuroinflammation in the brain. It has further been revealed that PKM2 exerts various biological functions in the regulation of energy supply, OS, inflammatory responses, and mitochondrial dysfunction. The roles of PKM2 are closely related to its different isoforms, expression levels in subcellular localization, and post-translational modifications. Therefore, summarizing the roles of PKM2 in CeVDs will help further understanding the molecular mechanisms of CeVDs. In this review, we illustrate the characteristics of PKM2, the regulated PKM2 expression, and the biological roles of PKM2 in CeVDs.

Pyruvate Kinase M2: A Potential Regulator of Cardiac Injury Through Glycolytic and Non-glycolytic Pathways

ABSTRACT

Adult animals are unable to regenerate heart cells due to postnatal cardiomyocyte cycle arrest, leading to higher mortality rates in cardiomyopathy. However, reprogramming of energy metabolism in cardiomyocytes provides a new perspective on the contribution of glycolysis to repair, regeneration, and fibrosis after cardiac injury. Pyruvate kinase (PK) is a key enzyme in the glycolysis process. This review focuses on the glycolysis function of PKM2, although PKM1 and PKM2 both play significant roles in the process after cardiac injury. PKM2 exists in both low-activity dimer and high-activity tetramer forms. PKM2 dimers promote aerobic glycolysis but have low catalytic activity, leading to the accumulation of glycolytic intermediates. These intermediates enter the pentose phosphate pathway to promote cardiomyocyte proliferation and heart regeneration. Additionally, they activate adenosine triphosphate (ATP)-sensitive K + (K ATP ) channels, protecting the heart against ischemic damage. PKM2 tetramers function similar to PKM1 in glycolysis, promoting pyruvate oxidation and subsequently ATP generation to protect the heart from ischemic damage. They also activate KDM5 through the accumulation of αKG, thereby promoting cardiomyocyte proliferation and cardiac regeneration. Apart from glycolysis, PKM2 interacts with transcription factors like Jmjd4, RAC1, β-catenin, and hypoxia-inducible factor (HIF)-1α, playing various roles in homeostasis maintenance, remodeling, survival regulation, and neovascularization promotion. However, PKM2 has also been implicated in promoting cardiac fibrosis through mechanisms like sirtuin (SIRT) 3 deletion, TG2 expression enhancement, and activation of transforming growth factor-β1 (TGF-β1)/Smad2/3 and Jak2/Stat3 signals. Overall, PKM2 shows promising potential as a therapeutic target for promoting cardiomyocyte proliferation and cardiac regeneration and addressing cardiac fibrosis after injury.

Importance of Michaelis Constants for Cancer Cell Redox Balance and Lactate Secretion-Revisiting the Warburg Effect

Cancer cells metabolize a large fraction of glucose to lactate, even under a sufficient oxygen supply. This phenomenon-the "Warburg Effect"-is often regarded as not yet understood. Cancer cells change gene expression to increase the uptake and utilization of glucose for biosynthesis pathways and glycolysis, but they do not adequately up-regulate the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS). Thereby, an increased glycolytic flux causes an increased production of cytosolic NADH. However, since the corresponding gene expression changes are not neatly fine-tuned in the cancer cells, cytosolic NAD+ must often be regenerated by loading excess electrons onto pyruvate and secreting the resulting lactate, even under sufficient oxygen supply. Interestingly, the Michaelis constants (KM values) of the enzymes at the pyruvate junction are sufficient to explain the priorities for pyruvate utilization in cancer cells: 1. mitochondrial OXPHOS for efficient ATP production, 2. electrons that exceed OXPHOS capacity need to be disposed of and secreted as lactate, and 3. biosynthesis reactions for cancer cell growth. In other words, a number of cytosolic electrons need to take the "emergency exit" from the cell by lactate secretion to maintain the cytosolic redox balance.

ULK1-dependent phosphorylation of PKM2 antagonizes O-GlcNAcylation and regulates the Warburg effect in breast cancer

Pyruvate kinase M2 (PKM2) is a central metabolic enzyme driving the Warburg effect in tumor growth. Previous investigations have demonstrated that PKM2 is subject to O-linked β-N-acetylglucosamine (O-GlcNAc) modification, which is a nutrient-sensitive post-translational modification. Here we found that unc-51 like autophagy activating kinase 1 (ULK1), a glucose-sensitive kinase, interacts with PKM2 and phosphorylates PKM2 at Ser333. Ser333 phosphorylation antagonizes PKM2 O-GlcNAcylation, promotes its tetramer formation and enzymatic activity, and decreases its nuclear localization. As PKM2 is known to have a nuclear role in regulating c-Myc, we also show that PKM2-S333 phosphorylation inhibits c-Myc expression. By downregulating glucose consumption and lactate production, PKM2 pS333 attenuates the Warburg effect. Through mouse xenograft assays, we demonstrate that the phospho-deficient PKM2-S333A mutant promotes tumor growth in vivo. In conclusion, we identified a ULK1-PKM2-c-Myc axis in inhibiting breast cancer, and a glucose-sensitive phosphorylation of PKM2 in modulating the Warburg effect.

Aerobic glycolysis of vascular endothelial cells: a novel perspective in cancer therapy

Vascular endothelial cells (ECs) are monolayers of cells arranged in the inner walls of blood vessels. Under normal physiological conditions, ECs play an essential role in angiogenesis, homeostasis and immune response. Emerging evidence suggests that abnormalities in EC metabolism, especially aerobic glycolysis, are associated with the initiation and progression of various diseases, including multiple cancers. In this review, we discuss the differences in aerobic glycolysis of vascular ECs under normal and pathological conditions, focusing on the recent research progress of aerobic glycolysis in tumor vascular ECs and potential strategies for cancer therapy.

PKM2 functions as a histidine kinase to phosphorylate PGAM1 and increase glycolysis shunts in cancer

Phosphoglycerate mutase 1 (PGAM1) is a key node enzyme that diverts the metabolic reactions from glycolysis into its shunts to support macromolecule biosynthesis for rapid and sustainable cell proliferation. It is prevalent that PGAM1 activity is upregulated in various tumors; however, the underlying mechanism remains unclear. Here, we unveil that pyruvate kinase M2 (PKM2) moonlights as a histidine kinase in a phosphoenolpyruvate (PEP)-dependent manner to catalyze PGAM1 H11 phosphorylation, that is essential for PGAM1 activity. Moreover, monomeric and dimeric but not tetrameric PKM2 are efficient to phosphorylate and activate PGAM1. In response to epidermal growth factor signaling, Src-catalyzed PGAM1 Y119 phosphorylation is a prerequisite for PKM2 binding and the subsequent PGAM1 H11 phosphorylation, which constitutes a discrepancy between tumor and normal cells. A PGAM1-derived pY119-containing cell-permeable peptide or Y119 mutation disrupts the interaction of PGAM1 with PKM2 and PGAM1 H11 phosphorylation, dampening the glycolysis shunts and tumor growth. Together, these results identify a function of PKM2 as a histidine kinase, and illustrate the importance of enzyme crosstalk as a regulatory mode during metabolic reprogramming and tumorigenesis.

Acetylation and Phosphorylation Regulate the Role of Pyruvate Kinase as a Glycolytic Enzyme or a Protein Kinase in Lamb

Protein post-translational modifications (PTMs) play an essential role in meat quality development. However, the effect of specific PTM sites on meat proteins has not been investigated yet. The characteristics of pyruvate kinase M (PKM) were found to exhibit a close correlation with final meat quality, and thus, serine 99 (S99) and lysine 137 (K137) in PKM were mutated to study their effect on PKM function. The structural and functional properties of five lamb PKM variants, including wild-type PKM (wtPKM), PKM_S99D (S99 phosphorylation), PKM_S99A (PKM S99 dephosphorylation), PKM_K137Q (PKM K137 acetylation), and PKM_K137R (PKM K137 deacetylation), were evaluated. The results showed that the secondary structure, tertiary structure, and polymer formation were affected among different PKM variants. In addition, the glycolytic activity of PKM_K137Q was decreased because of its weakened binding with phosphoenolpyruvate. In the PKM_K137R variant, the actin phosphorylation level exhibited a decrease, suggesting a low kinase activity of PKM_K137R. The results of molecular simulation showed a 42% reduction in the interface area between PKM_K137R and actin, in contrast to wtPKM and actin. These findings are significant for revealing the mechanism of how PTMs regulate PKM function and provide a theoretical foundation for the development of precise meat quality preservation technology.

Imbalance in Glucose Metabolism Regulates the Transition of Microglia from Homeostasis to Disease-Associated Microglia Stage 1

Microglia undergo two-stage activation in neurodegenerative diseases, known as disease-associated microglia (DAM). TREM2 mediates the DAM2 stage transition, but what regulates the first DAM1 stage transition is unknown. We report that glucose dyshomeostasis inhibits DAM1 activation and PKM2 plays a role. As in tumors, PKM2 was aberrantly elevated in both male and female human AD brains, but unlike in tumors, it is expressed as active tetramers, as well as among TREM2+ microglia surrounding plaques in 5XFAD male and female mice. snRNAseq analyses of microglia without Pkm2 in 5XFAD mice revealed significant increases in DAM1 markers in a distinct metabolic cluster, which is enriched in genes for glucose metabolism, DAM1, and AD risk. 5XFAD mice incidentally exhibited a significant reduction in amyloid pathology without microglial Pkm2 Surprisingly, microglia in 5XFAD without Pkm2 exhibited increases in glycolysis and spare respiratory capacity, which correlated with restoration of mitochondrial cristae alterations. In addition, in situ spatial metabolomics of plaque-bearing microglia revealed an increase in respiratory activity. These results together suggest that it is not only glycolytic but also respiratory inputs that are critical to the development of DAM signatures in 5XFAD mice.

Targeting PKM2 signaling cascade with salvianic acid A normalizes tumor blood vessels to facilitate chemotherapeutic drug delivery

Aberrant tumor blood vessels are prone to propel the malignant progression of tumors, and targeting abnormal metabolism of tumor endothelial cells emerges as a promising option to achieve vascular normalization and antagonize tumor progression. Herein, we demonstrated that salvianic acid A (SAA) played a pivotal role in contributing to vascular normalization in the tumor-bearing mice, thereby improving delivery and effectiveness of the chemotherapeutic agent. SAA was capable of inhibiting glycolysis and strengthening endothelial junctions in the human umbilical vein endothelial cells (HUVECs) exposed to hypoxia. Mechanistically, SAA was inclined to directly bind to the glycolytic enzyme PKM2, leading to a dramatic decrease in endothelial glycolysis. More importantly, SAA improved the endothelial integrity via activating the β-Catenin/Claudin-5 signaling axis in a PKM2-dependent manner. Our findings suggest that SAA may serve as a potent agent for inducing tumor vascular normalization.

Exploring the diverse role of pyruvate kinase M2 in cancer: Navigating beyond glycolysis and the Warburg effect

Pyruvate Kinase M2, a key enzyme in glycolysis, has garnered significant attention in cancer research due to its pivotal role in the metabolic reprogramming of cancer cells. Originally identified for its association with the Warburg effect, PKM2 has emerged as a multifaceted player in cancer biology. The functioning of PKM2 is intricately regulated at multiple levels, including controlling the gene expression via various transcription factors and non-coding RNAs, as well as adding post-translational modifications that confer distinct functions to the protein. Here, we explore the diverse functions of PKM2, encompassing newly emerging roles in non-glycolytic metabolic regulation, immunomodulation, inflammation, DNA repair and mRNA processing, beyond its canonical role in glycolysis. The ever-expanding list of its functions has recently grown to include roles in subcellular compartments such as the mitochondria and extracellular milieu as well, all of which make PKM2 an attractive drug target in the pursuit of therapeutics for cancer.

The role of PKM2 in cancer progression and its structural and biological basis

Pyruvate kinase M2 (PKM2), a subtype of pyruvate kinase (PK), has been shown to play an important role in the development of cancer. It regulates the last step of glycolytic pathway. PKM2 has both pyruvate kinase and protein kinase activity, and the conversion of these two functions of PKM2 depends on the mutual change of dimer and tetramer. The dimerization of PKM2 can promote the proliferation and growth of tumor cells, so inhibiting the dimerization of PKM2 is essential to curing cancer. The aggregation of PKM2 is regulated by both endogenous and exogenous cofactors as well as post-translational modification (PTM). Although there are many studies on the different aggregation of PKM2 in the process of tumor development, there are few summaries in recent years. In this review, we first introduce the role of PKM2 in various biological processes of tumor growth. Then, we summarize the aggregation regulation mechanism of PKM2 by various endogenous cofactors such as Fructose-1, 6-diphosphate (FBP), various amino acids, and post-translational modification (PTMs). Finally, the related inhibitors and agonists of PKM2 are summarized to provide reference for regulating PKM2 aggregation in the treatment of cancer in the future.

Tyrosine phosphatase SHP2 aggravates tumor progression and glycolysis by dephosphorylating PKM2 in gastric cancer

Gastric cancer (GC) is among the most lethal human malignancies, yet it remains hampered by challenges in fronter of molecular-guided targeted therapy to direct clinical treatment strategies. The protein tyrosine phosphatase Src homology 2 domain-containing phosphatase 2 (SHP2) is involved in the malignant progression of GC. However, the detailed mechanisms of the posttranslational modifications of SHP2 remain poorly understood. Herein, we demonstrated that an allosteric SHP2 inhibitor, SHP099, was able to block tumor proliferation and migration of GC by dephosphorylating the pyruvate kinase M2 type (PKM2) protein. Mechanistically, we found that PKM2 is a bona fide target of SHP2. The dephosphorylation and activation of PKM2 by SHP2 are necessary to exacerbate tumor progression and GC glycolysis. Moreover, we demonstrated a strong correlation between the phosphorylation level of PKM2 and adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) in GC cells. Notably, the low phosphorylation expression of AMPK was negatively correlated with activated SHP2. Besides, we proved that cisplatin could activate SHP2 and SHP099 increased sensitivity to cisplatin in GC. Taken together, our results provide evidence that the SHP2/PKM2/AMPK axis exerts a key role in GC progression and glycolysis and could be a viable therapeutic approach for the therapy of GC.

CIP2A induces PKM2 tetramer formation and oxidative phosphorylation in non-small cell lung cancer

Tumor cells are usually considered defective in mitochondrial respiration, but human non-small cell lung cancer (NSCLC) tumor tissues are shown to have enhanced glucose oxidation relative to adjacent benign lung. Here, we reported that oncoprotein cancerous inhibitor of protein phosphatase 2A (CIP2A) inhibited glycolysis and promoted oxidative metabolism in NSCLC cells. CIP2A bound to pyruvate kinase M2 (PKM2) and induced the formation of PKM2 tetramer, with serine 287 as a novel phosphorylation site essential for PKM2 dimer-tetramer switching. CIP2A redirected PKM2 to mitochondrion, leading to upregulation of Bcl2 via phosphorylating Bcl2 at threonine 69. Clinically, CIP2A level in tumor tissues was positively correlated with the level of phosphorylated PKM2 S287. CIP2A-targeting compounds synergized with glycolysis inhibitor in suppressing cell proliferation in vitro and in vivo. These results indicated that CIP2A facilitates oxidative phosphorylation by promoting tetrameric PKM2 formation, and targeting CIP2A and glycolysis exhibits therapeutic potentials in NSCLC.

Unraveling the intricacies of osteoclast differentiation and maturation: insight into novel therapeutic strategies for bone-destructive diseases

Osteoclasts are the principal cells that efficiently resorb bone. Numerous studies have attempted to reveal the molecular pathways leading to the differentiation and activation of osteoclasts to improve the treatment and prevention of osteoporosis and other bone-destructive diseases. While the cumulative knowledge of osteoclast regulatory molecules, such as receptor activator of nuclear factor-kB ligand (RANKL) and nuclear factor of activated T cells 1 (NFATc1), contributes to the understanding of the developmental progression of osteoclasts, little is known about how the discrete steps of osteoclastogenesis modify osteoclast status but not the absolute number of osteoclasts. The regulatory mechanisms involved in osteoclast maturation but not those involved in differentiation deserve special attention due to their potential use in establishing a more effective treatment strategy: targeting late-phase differentiation while preserving coupled bone formation. Recent studies have shed light on the molecules that govern late-phase osteoclast differentiation and maturation, as well as the metabolic changes needed to adapt to shifting metabolic demands. This review outlines the current understanding of the regulation of osteoclast differentiation, as well as osteoclast metabolic adaptation as a differentiation control mechanism. Additionally, this review introduces molecules that regulate the late-phase osteoclast differentiation and thus minimally impact coupled bone formation.

Histone Acyl Code in Precision Oncology: Mechanistic Insights from Dietary and Metabolic Factors

Cancer etiology involves complex interactions between genetic and non-genetic factors, with epigenetic mechanisms serving as key regulators at multiple stages of pathogenesis. Poor dietary habits contribute to cancer predisposition by impacting DNA methylation patterns, non-coding RNA expression, and histone epigenetic landscapes. Histone post-translational modifications (PTMs), including acyl marks, act as a molecular code and play a crucial role in translating changes in cellular metabolism into enduring patterns of gene expression. As cancer cells undergo metabolic reprogramming to support rapid growth and proliferation, nuanced roles have emerged for dietary- and metabolism-derived histone acylation changes in cancer progression. Specific types and mechanisms of histone acylation, beyond the standard acetylation marks, shed light on how dietary metabolites reshape the gut microbiome, influencing the dynamics of histone acyl repertoires. Given the reversible nature of histone PTMs, the corresponding acyl readers, writers, and erasers are discussed in this review in the context of cancer prevention and treatment. The evolving 'acyl code' provides for improved biomarker assessment and clinical validation in cancer diagnosis and prognosis.

Glycolysis: an emerging regulator of osteoarthritis

Osteoarthritis (OA) has been a leading cause of disability in the elderly and there remains a lack of effective therapeutic approaches as the mechanisms of pathogenesis and progression have yet to be elucidated. As OA progresses, cellular metabolic profiles and energy production are altered, and emerging metabolic reprogramming highlights the importance of specific metabolic pathways in disease progression. As a crucial part of glucose metabolism, glycolysis bridges metabolic and inflammatory dysfunctions. Moreover, the glycolytic pathway is involved in different areas of metabolism and inflammation, and is associated with a variety of transcription factors. To date, it has not been fully elucidated whether the changes in the glycolytic pathway and its associated key enzymes are associated with the onset or progression of OA. This review summarizes the important role of glycolysis in mediating cellular metabolic reprogramming in OA and its role in inducing tissue inflammation and injury, with the aim of providing further insights into its pathological functions and proposing new targets for the treatment of OA.

Revving the engine: PKB/AKT as a key regulator of cellular glucose metabolism

Glucose metabolism is of critical importance for cell growth and proliferation, the disorders of which have been widely implicated in cancer progression. Glucose uptake is achieved differently by normal cells and cancer cells. Even in an aerobic environment, cancer cells tend to undergo metabolism through glycolysis rather than the oxidative phosphorylation pathway. Disordered metabolic syndrome is characterized by elevated levels of metabolites that can cause changes in the tumor microenvironment, thereby promoting tumor recurrence and metastasis. The activation of glycolysis-related proteins and transcription factors is involved in the regulation of cellular glucose metabolism. Changes in glucose metabolism activity are closely related to activation of protein kinase B (PKB/AKT). This review discusses recent findings on the regulation of glucose metabolism by AKT in tumors. Furthermore, the review summarizes the potential importance of AKT in the regulation of each process throughout glucose metabolism to provide a theoretical basis for AKT as a target for cancers.

M-type pyruvate kinase 2 (PKM2) tetramerization alleviates the progression of right ventricle failure by regulating oxidative stress and mitochondrial dynamics

BACKGROUND

Right ventricle failure (RVF) is a progressive heart disease that has yet to be fully understood at the molecular level. Elevated M-type pyruvate kinase 2 (PKM2) tetramerization alleviates heart failure, but detailed molecular mechanisms remain unclear.

OBJECTIVE

We observed changes in PKM2 tetramerization levels during the progression of right heart failure and in vitro cardiomyocyte hypertrophy and explored the causal relationship between altered PKM2 tetramerization and the imbalance of redox homeostasis in cardiomyocytes, as well as its underlying mechanisms. Ultimately, our goal was to propose rational intervention strategies for the treatment of RVF.

METHOD

We established RVF in Sprague Dawley (SD) rats by intraperitoneal injection of monocrotaline (MCT). The pulmonary artery pressure and right heart function of rats were assessed using transthoracic echocardiography combined with right heart catheterization. TEPP-46 was used both in vivo and in vitro to promote PKM2 tetramerization.

RESULTS

We observed that oxidative stress and mitochondrial disorganization were associated with increased apoptosis in the right ventricular tissue of RVF rats. Quantitative proteomics revealed that PKM2 was upregulated during RVF and negatively correlated with the cardiac function. Facilitating PKM2 tetramerization promoted mitochondrial network formation and alleviated oxidative stress and apoptosis during cardiomyocyte hypertrophy. Moreover, enhancing PKM2 tetramer formation improved cardiac mitochondrial morphology, mitigated oxidative stress and alleviated heart failure.

CONCLUSION

Disruption of PKM2 tetramerization contributed to RVF by inducing mitochondrial fragmentation, accumulating ROS, and finally promoted the progression of cardiomyocyte apoptosis. Facilitating PKM2 tetramerization holds potential as a promising therapeutic approach for RVF.

Role of HIF in fish inflammation

The hypoxia-inducing factor (HIF) is a central transcription factor in cellular oxygen sensing and regulation. It is common that the inflammation always appears in many diseases, like infectious diseases in fishes, and the inflammation is often accompanied by hypoxia, as a hallmark of inflammation. Besides coordinating cellular responses to low oxygen, HIF-mediated hypoxia signaling pathway is also crucial for immune responses such as the regulations of innate immune cell phenotype and function, as well as metabolic reprogramming under the inflammation. However, the understanding of the molecular mechanisms by which HIFs regulate the inflammatory response in fish is still very limited. Here, we review the characteristics of HIF as well as its roles in innate immune cells and the infections caused by bacteria and viruses. The regulatory effects of HIF on the metabolic reprogramming of innate immune cells are also discussed and the future research directions are outlooked. This paper will serve as a reference for elucidating the molecular mechanism of HIF regulating inflammation and identifying treatment strategies to target HIF for fish disease.

An insight into the structure-activity relationship studies of anticancer medicinal attributes of 7-azaindole derivatives: a review

In the current portfolio, there is a lot of interest in the 7-azaindole building block for drug discovery. The creation of synthetic, sophisticated methods for the modification of 7-azaindoles is a promising area of research. This review covers the structure-activity relationship of 7-azaindole analogs, which have been shown to be effective anticancer agents in the literature of the past two decades. Positions 1, 3 and 5 of the 7-azaindole ring are the most active sites. Disubstitution is used for the synthesis of a new analog of the 7-azaindole moiety. All positions are used to create novel molecules that are effective anticancer agents. The alkyl, aryl carboxamide group and heterocyclic ring are the most successful types of substitution.

Metabolic targeting of platelets to combat thrombosis: dawn of a new paradigm?

Current antithrombotic therapies used in clinical settings target either the coagulation pathways or platelet activation receptors (P2Y12 or GPIIb/IIIa), as well as the cyclooxygenase (COX) enzyme through aspirin. However, they are associated with bleeding risk and are not suitable for long-term use. Thus, novel strategies which provide broad protection against platelet activation with minimal bleeding risks are required. Regardless of the nature of agonist stimulation, platelet activation is an energy-intensive and ATP-driven process characterized by metabolic switching toward a high rate of aerobic glycolysis, relative to oxidative phosphorylation (OXPHOS). Consequently, there has been considerable interest in recent years in investigating whether targeting metabolic pathways in platelets, especially aerobic glycolysis and OXPHOS, can modulate their activation, thereby preventing thrombosis. This review briefly discusses the choices of metabolic substrates available to platelets that drive their metabolic flexibility. We have comprehensively elucidated the relevance of aerobic glycolysis in facilitating platelet activation and the underlying molecular mechanisms that trigger this switch from OXPHOS. We have provided a detailed account of the antiplatelet effects of targeting vital metabolic checkpoints such as pyruvate dehydrogenase kinases (PDKs) and pyruvate kinase M2 (PKM2) that preferentially drive the pyruvate flux to aerobic glycolysis. Furthermore, we discuss the role of fatty acids and glutamine oxidation in mitochondria and their subsequent role in driving OXPHOS and platelet activation. While the approach of targeting metabolic regulatory mechanisms in platelets to prevent their activation is still in a nascent stage, accumulating evidence highlights its beneficial effects as a potentially novel antithrombotic strategy.

Antiviral epithelial-macrophage crosstalk permits secondary bacterial infections

IMPORTANCE

Miscommunication of antiviral and antibacterial immune signals drives worsened morbidity and mortality during respiratory viral-bacterial coinfections. Extracellular vesicles (EVs) are a form of intercellular communication with broad implications during infection, and here we show that epithelium-derived EVs released during the antiviral response impair the antibacterial activity of macrophages, an innate immune cell crucial for bacterial control in the airway. Macrophages exposed to antiviral EVs display reduced clearance of Staphylococcus aureus as well as altered inflammatory signaling and anti-inflammatory metabolic reprogramming, thus revealing EVs as a source of dysregulated epithelium-macrophage crosstalk during coinfection. As effective epithelium-macrophage communication is critical in mounting an appropriate immune response, this novel observation of epithelium-macrophage crosstalk shaping macrophage metabolism and antimicrobial function provides exciting new insight and improves our understanding of immune dysfunction during respiratory coinfections.