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Endothelial cell (EC) senescence and vascular aging are important hallmarks of chronic metabolic diseases. An improved understanding of the precise regulation of EC senescence may provide novel therapeutic strategies for EC and vascular aging-related diseases. This study examined the potential functions of Spinster homolog 2 (SPNS2) in EC senescence and vascular aging. We discovered that the expression of SPNS2 was significantly lower in older adults, aged mice, hydrogen peroxide-induced EC senescence models and EC replicative senescence model, and was correlated with the expression of aging-related factors. in vivo experiments showed that the EC-specific knockout of SPNS2 markedly aggravated vascular aging by substantially, impairing vascular structure and function, as evidenced by the abnormal expression of aging factors, increased inflammation, reduced blood flow, pathological vessel dilation, and elevated collagen levels in a naturally aging mouse model. Moreover, RNA sequencing and molecular biology analyses revealed that the loss of SPNS2 in ECs increased cellular senescence biomarkers, aggravated the senescence-associated secretory phenotype (SASP), and inhibited cell proliferation. Mechanistically, silencing SPNS2 disrupts pyruvate metabolism homeostasis via pyruvate kinase M (PKM), resulting in mitochondrial dysfunction and EC senescence. Overall, SPNS2 expression and its functions in the mitochondria are crucial regulators of EC senescence and vascular aging. [ABSTRACT FROM AUTHOR]

Recent studies have shown that high dietary fructose intake enhances intestinal tumor growth in mice. Our previous work indicated that glucose enables hypoxic colorectal cancer (CRC) cells to resist receptor-interacting protein (RIP)-dependent necroptosis. Despite having the same chemical formula, glucose and fructose are absorbed through different transporters yet both can enter the glycolytic metabolic pathway. The excessive intake of dietary fructose, leading to its overflow into the colon, allows colonic cells to absorb fructose apically. This study explores the mechanisms behind apical fructose-mediated death resistance in CRC cells under hypoxic stress. Utilizing three CRC cell lines (Caco-2, HT29, and T84) under normoxic and hypoxic conditions with varying fructose concentrations, we assessed lactate dehydrogenase (LDH) activity, RIP1/3 complex formation (a necroptosis marker), and cell integrity. We investigated the role of fructose in glycolytic-mediated death resistance using glycolytic inhibitors iodoacetate (IA, a glycolytic inhibitor to glyceraldehyde 3-phosphate dehydrogenase), and UK5099 (UK, an inhibitor to mitochondrial pyruvate carrier). Our findings reveal that apical fructose prevents the hypoxia-induced RIP-dependent necroptosis in Caco-2 and HT29 cells. Fructose exposure under hypoxia also preserved epithelial integrity. IA, but not UK, blocked fructose-mediated glycolytic metabolite production and necrosis, indicating that anaerobic glycolytic metabolites facilitate death resistance. Notably, fructose treatment upregulated pyruvate kinase (PK)-M1 mRNA in hypoxic Caco-2 and HT29 cells, while PKM2 upregulation was exclusive to HT29 cells. In conclusion, apical fructose utilization through glycolysis effectively inhibits hypoxia-induced RIP-dependent necroptosis in CRC cells, shedding light on potential metabolic adaptation mechanisms in the tumor microenvironment and suggesting novel targets for therapeutic intervention. [ABSTRACT FROM AUTHOR]

Cancer is a global health challenge, despite significant advancements in research. Addressing this issue, we report the design, synthesis and biological evaluation of pyrimidinyl indoles as potential antineoplastic agents. Pyrimidinyl indoles interact with pyruvate kinase isoform M2 (PKM2), which is commonly overexpressed in oral, lung, breast and colorectal cancers. In silico studies indicated that these molecules are having affinity towards PKM2 and targeting key residues such as Phe26, Leu27, Tyr390, Gln393, Leu394 and Glu397 at the interfacial active site region between the two chains of PKM2. Thereafter compounds were designed, synthesized and characterized using nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and mass spectrometry (MS). This was followed by in vitro screening using cell lines and enzyme‐coupled assays. One of the designed PKM2 inhibitor demonstrated potent anticancer activity against MCF‐7 (Breast Cancer) cells while sparing normal MCF‐10 A breast cells. Molecular dynamics (MD) simulation studies showed that the developed inhibitor stabilized the PKM2 active site over a 100 ns simulation. [ABSTRACT FROM AUTHOR]

Simple Summary: When faced with starvation, fish can consume energy reserves and adaptively modify the metabolic responses of main energy substrates for fundamental activity. Carbohydrates and lipids are mobilized preferentially in most fish under starvation. However, the mobilization of endogenous energy in starving fish varies with the species, tissue, and fasting duration. Liver tissue is the primary tissue for energy reserves in multiple fish, particularly lipid-associated components. Therefore, this study was conducted to investigate the phenotypic changes in physiological, metabolic, histological, and molecular characteristics of glucose and lipid metabolism in the liver of Synechogobius hasta experiencing different starvation periods. Hepatic glycogen and triglycerides were concurrently mobilized in S. hasta during starvation, which was accompanied by consistent changes in liver intermediary metabolism enzyme activities and an increase in liver antioxidant capacity to some extent. S. hasta livers exhibited evident vacuolations, larger intercellular spaces, and other microstructural abnormalities from the third day of starvation. Additionally, fasting not only transcriptionally attenuated glucose and lipid anabolism, but also enhanced the catabolic pathway and fatty acid transport in S. hasta liver. These findings may provide preliminary data for further assessing the energy strategy to cope with starvation and the underlying mechanism in S. hasta and other fish species. In this study, the influence of fasting on hepatic glucose and lipid metabolism was explored by examining biochemical, antioxidative, and morphological indicators and transcriptional expression in the liver of javelin goby (Synechogobius hasta) after 0, 3, 7, or 14 days of starvation. Marked reductions in hepatic glycogen and triglycerides occurred from the seventh day of starvation until the end of the trial (p < 0.05). However, no alterations in hepatic cholesterol or protein were detected throughout the entire experiment (p > 0.05). During fasting, the activities of pyruvate kinase, lactate dehydrogenase, and glycogen phosphorylase a all rose firstly and then fell (p < 0.05). The activities of hepatic fatty acid synthase and acetyl-CoA carboxylase were minimized to their lowest levels at the end of food deprivation (p < 0.05), while lipase was elevated after 7–14 days of fasting (p < 0.05). Catalase, glutathione, and the total antioxidative capacity were increased and maintained their higher values in the later stage of fasting (p < 0.05), whereas malondialdehyde was not significantly changed (p > 0.05). Hepatic vein congestion, remarkable cytoplasmic vacuoles, and irregular cell shape were present in S. hasta which endured 3–7 days of fasting and were less pronounced when food shortage was prolonged. In terms of genes associated with glucose and lipid metabolism, the hepatic phosphofructokinase gene was constantly up-regulated during fasting (p < 0.05). However, the mRNA levels of glycogen synthase and glucose-6-phosphatase were obviously lower when the food scarcity extended to 7 days or more (p < 0.05). Fatty acid synthase, stearoyl-CoA desaturase 1, and peroxisome proliferator-activated receptor γ were substantially down-regulated in S. hasta livers after 7–14 days of food deprivation (p < 0.05). However, genes involved in lipolysis and fatty acid transport were transcriptionally enhanced to varying extents and peaked at the end of fasting (p < 0.05). Overall, starvation lasting 7 days or more could concurrently mobilize hepatic carbohydrates and fat as energy resources and diminished their hepatic accumulation by suppressing biosynthesis and enhancing catabolism and transport, ultimately metabolically and structurally perturbing the liver in S. hasta. This work presents preliminary data on the dynamic characteristics of hepatic glucose and lipid metabolism in S. hasta in response to starvation, which may shed light on the sophisticated mechanisms of energetic homeostasis in fish facing nutrient unavailability and may benefit the utilization/conservation of S. hasta. [ABSTRACT FROM AUTHOR]

Cipangopaludina chinensis is a common freshwater mollusk that is widely distributed worldwide, especially in China. In our research, 1,382 proteins and 1,039 phosphorylated proteins were identified from C. chinensis carcasses, and 690 differentially expressed proteins (DEPs) were quantified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that the DEPs are involved in cellular processes, single-organism processes, metabolic processes, developmental processes, localization, and biological regulation. The phosphorylated proteins were found to be related to the Rap1 signaling pathway, Ras signaling pathway, calcium signaling pathway, and longevity-regulating pathways. Moreover, we also identified important regulatory enzymes, such as guanylate cyclase, tyrosine protein kinase, receptor protein tyrosine kinase, and glyoxylate reductase/hydroxypyruvate reductase. Notably, we found guanylate cyclase to be present in multiple signaling pathways, including the Rap1 signaling pathway, calcium signaling pathway, Ras signaling pathway, insulin secretion, longevity regulating pathway, glutamatergic synapse, circadian entrainment, and gap junction. This enzyme may play a crucial role in regulating molecular mechanisms in C. chinensis. In summary, proteomic and phosphoproteomic analyses of C. chinensis carcasses displayed significant differences among different geographical isolates, which helps enhance our understanding of food nutrition, signaling pathways, and metabolic mechanisms in C. chinensis. [ABSTRACT FROM AUTHOR]

Background: At present, hepatic ischemia-reperfusion injury (IRI) is an important complication of partial hepatectomy and liver transplantation, and it is an important cause of poor prognosis. Spleen tyrosine kinase(SYK) plays an important role in a variety of signaling pathways in the liver, but its role in hepatic IRI is still unclear. This study aims to investigate the role and mechanism of SYK in hepatic IRI and tumor recurrence. Methods: We first observed the activation of SYK in the liver of mice in response to hepatic IRI. Subsequently, Pharmacological inhibitions of SYK were used to evaluated the effect of SYK on neutrophil recruitment and NETosis, and further explored the effect of SYK on IRI and tumor recurrence. Results: Our study shows that SYK is activated in response to hepatic IRI and aggravates liver injury. On the one hand, neutrophils SYK during the early stage of liver reperfusion increases neutrophil extracellular traps (NETs) production by promoting Pyruvate kinase M2(PKM2) nuclear translocation leading to upregulation of phosphorylated STAT3, thereby exacerbating liver inflammation and tumor recurrence. On the other hand, macrophages SYK can promote the recruitment of neutrophils and increase the activation of NLRP3 inflammasome and IL1β, which further promotes the formation of NETs. Conclusions: Our study demonstrates that neutrophil and macrophage SYK synergistically promote hepatic IRI and tumor recurrence, and SYK may be a potential target to improve postoperative hepatic IRI and tumor recurrence. [ABSTRACT FROM AUTHOR]

Background: Pyruvate kinase (PK) deficiency is an inherited red blood cell (RBC) enzyme disorder that results in non-immune chronic hemolytic anemia. Characteristic symptoms of PK deficiency include anemia, fatigue, splenomegaly, jaundice, gallstones, thrombosis, and transfusional iron overload. Previously, treatments aimed at symptomatic management with RBC transfusions, phototherapy, folic acid supplementation, splenectomy, and iron chelation therapy when iron overload was documented. Mitapivat, a recently approved medication for treatment of PK-deficiency hemolytic anemia, is an oral allosteric activator of wild-type and mutant RBC PK enzymes. In this paper, we describe three cases of PK-deficiency anemia treated with mitapivat and describe modern management of this rare hemolytic disorder. Methods: A retrospective healthcare database analysis was conducted to extract relevant information. Both quantitative and qualitative methods were integrated to provide a more comprehensive understanding of the cases. Results: Two patients responded well to treatment with mitapivat, noted by an increase in hemoglobin levels, improvements in hemolytic markers, less frequent or no RBC transfusion requirements, and improvements in fatigue. One patient carrying two non-missense mutations of the PKLR gene did not respond to treatment with mitapivat. As variations in patient-specific factors (including genotype) can lead to different clinical manifestations and responses to treatment, we recommend considering both the phenotype (clinical symptoms and signs) and the genotype of the PKLR gene when making therapeutic decisions about starting a patient on mitapivat. Conclusions: While mitapivat addresses the previously unmet needs of most patients with PK deficiency as the first and only disease-modifying medication to receive approval for this condition, not all patients with PK deficiency are amenable to treatment with mitapivat. [ABSTRACT FROM AUTHOR]

Cardiac metabolism ensures a continuous ATP supply, primarily using fatty acids in a healthy state and favoring glucose in pathological conditions. Pyruvate kinase muscle (PKM) controls the final step of glycolysis, with PKM1 being the main isoform in the heart. PKM2, elevated in various heart diseases, has been suggested to play a protective role in cardiac stress, but its function in basal cardiac metabolism remains unclear. We examined hearts from global PKM2 knockout (PKM2−/−) mice and found reduced intracellular glucose. Isotopic tracing of U‐13C glucose revealed a shift to biosynthetic pathways in PKM2−/− cardiomyocytes. Total ATP content was two‐thirds lower in PKM2−/− hearts, and functional analysis indicated reduced mitochondrial oxygen consumption. Total reactive oxygen species (ROS) and mitochondrial superoxide were also increased in PKM2−/− cardiomyocytes. Intriguingly, PKM2−/− hearts had preserved ejection fraction compared to controls. Mechanistically, increased calcium/calmodulin‐dependent kinase II activity and phospholamban phosphorylation may contribute to higher sarcoendoplasmic reticulum calcium ATPase 2 pump activity in PKM2−/− hearts. Loss of PKM2 led to altered glucose metabolism, diminished mitochondrial function, and increased ROS in cardiomyocytes. These data suggest that cardiac PKM2 acts as an important rheostat to maintain ATP levels while limiting oxidative stress. Although loss of PKM2 did not impair baseline contractility, its absence may make hearts more sensitive to environmental stress or injury. [ABSTRACT FROM AUTHOR]

Though Ginsenoside F2 (GF2), a protopanaxadiol saponin from Panax ginseng, is known to have an anticancer effect, its underlying mechanism still remains unclear. In our model, the anti-glycolytic mechanism of GF2 was investigated in human cervical cancer cells in association with miR193a-5p and the β-catenin/c-Myc/Hexokinase 2 (HK2) signaling axis. Here, GF2 exerted significant cytotoxicity and antiproliferation activity, increased sub-G1, and attenuated the expression of pro-Poly (ADPribose) polymerase (pro-PARP) and pro-cysteine aspartyl-specific protease (procaspase3) in HeLa and SiHa cells. Consistently, GF2 attenuated the expression of Wnt, β-catenin, and c-Myc and their downstream target genes such as HK2, pyruvate kinase isozymes M2 (PKM2), and lactate dehydrogenase A (LDHA), along with a decreased production of glucose and lactate in HeLa and SiHa cells. Moreover, GF2 suppressed β-catenin and c-Myc stability in the presence and absence of cycloheximide in HeLa cells, respectively. Additionally, the depletion of β-catenin reduced the expression of c-Myc and HK2 in HeLa cells, while pyruvate treatment reversed the ability of GF2 to inhibit β-catenin, c-Myc, and PKM2 in GF2-treated HeLa cells. Notably, GF2 upregulated the expression of microRNA139a-5p (miR139a-5p) in HeLa cells. Consistently, the miR139a-5p mimic enhanced the suppression of β-catenin, c-Myc, and HK2, while the miR193a-5p inhibitor reversed the ability of GF2 to attenuate the expression of β-catenin, c-Myc, and HK2 in HeLa cells. Overall, these findings suggest that GF2 induces apoptosis via the activation of miR193a-5p and the inhibition of β-catenin/c-Myc/HK signaling in cervical cancer cells. [ABSTRACT FROM AUTHOR]

Background and Objectives: To evaluate the clinical findings of glucose 6-phosphate dehydrogenase (G6PD) and pyruvate kinase (PK) deficiency in prolonged jaundice and to determine whether the systemic immune inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) can be used in the diagnosis of neonatal prolonged jaundice. Materials and Methods: Among full-term neonates with hyperbilirubinemia who were admitted to Medicine Hospital between January 2019 and January 2024 with the complaint of jaundice, 167 infants with a serum bilirubin level above 10 mg/dL, whose jaundice persisted after the 10th day, were included in this study. Results: G6PD activity was negatively correlated with NLR, SII, age, and hematocrit (Hct). There was a weak negative correlation between G6PD and NLR and a moderate negative correlation between G6PD activity and SII when adjusted for age and Hct. PK activity showed no significant correlation with G6PD, NLR, PLR, SII, age, and Hct. A linear relationship was observed between G6PD activity and SII and NLR. Conclusions: NLR and SII can be easily calculated in the evaluation of prolonged jaundice in G6PD deficiency has a considerable advantage. NLR and SII levels may contribute by preventing further tests for prolonged jaundice and regulating its treatment. It may be useful to form an opinion in emergencies and in early diagnostic period. [ABSTRACT FROM AUTHOR]

The immune system requires a high energy expenditure to resist pathogen invasion. Macrophages undergo metabolic reprogramming to meet these energy requirements and immunologic activity and polarize to M1-type macrophages. Understanding the metabolic pathway switching in large yellow croaker (Larimichthys crocea) macrophages in response to lipopolysaccharide (LPS) stimulation and whether this switching affects immunity is helpful in explaining the stronger immunity of hypoxia-tolerant L. crocea. In this study, transcript levels of glycolytic pathway genes (Glut1 and Pdk1), mRNA levels or enzyme activities of glycolytic enzymes [hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase A (LDHA)], aerobic respiratory enzymes [pyruvate dehydrogenase (PDH), isocitrate dehydrogenase (IDH), and succinate dehydrogenase (SDH)], metabolites [lactic acid (LA) and adenosine triphosphate (ATP)], levels of bactericidal products [reactive oxygen species (ROS) and nitric oxide (NO)], and transcripts and level changes of inflammatory factors [IL1β, TNFα, and interferon (IFN) γ] were detected in LPSstimulated L. crocea head kidney macrophages. We showed that glycolysis was significantly induced, the tricarboxylic acid (TCA) cycle was inhibited, and metabolic reprogramming occurred, showing the Warburg effect when immune cells were activated. To determine the potential regulatory mechanism behind these changes, LcHIF-1α was detected and found to be significantly induced and transferred to the nucleus after LPS stimulation. LcHif-1a interference led to a significant reduction in glycolytic pathway gene transcript expression, enzyme activity, metabolites, bactericidal substances, and inflammatory factor levels; a significant increase in the aerobic respiration enzymes; and decreased migration, invasion, and phagocytosis. Further ultrastructural observation by electron microscopy showed that fewer microspheres contained phagocytes and that more cells were damaged after LcHif-1α interference. LcHif-1α overexpression L. crocea head kidney macrophages showed the opposite trend, and promoter activities of Ldha and Il1β were significantly enhanced after LcHif-1α overexpression in HEK293T cells. Our data showed that LcHIF-1α acted as a metabolic switch in L. crocea macrophages and was important in polarization. Hypoxia-tolerant L. crocea head kidney showed a stronger Warburg effect and inhibited the TCA cycle, higher metabolites, and bactericidal substance levels. These results collectively revealed that LcHif-1α may promote the functional activities of head kidney macrophages in protecting hypoxia-tolerant L. crocea from Aeromonas hydrophila infection. [ABSTRACT FROM AUTHOR]

Fumonisin B1 (FB1), a mycotoxin produced by Fusarium species, is prevalent in crops and animal feed, posing significant health risks to livestock and humans. FB1 induces oxidative stress in Sertoli cells, destroys testicular structure, and affects spermatogenesis. However, methods to mitigate the reproductive toxicity of FB1 in testes remain unknown. Quercetin, a natural flavonoid antioxidant, may offer protective benefits. This study investigated the protective effects and mechanisms of quercetin against FB1-induced reproductive toxicity in TM4 cells (a Sertoli cell line). The results indicated that 40 μM quercetin improved cell viability, reduced apoptosis, and preserved cell functions. Quercetin also decreased reactive oxygen species (ROS) levels in TM4 cells exposed to FB1, enhanced the expression of antioxidant genes, and improved mitochondrial membrane potential. Compared with FB1 alone, the combination of quercetin and FB1 increased ATP levels, as well as pyruvate and lactic acid, the key glycolysis products. Furthermore, this combination elevated the mRNA and protein expression of glycolysis-related genes, including glucose-6-phosphate isomerase 1 (Gpi1), hexokinase 2 (Hk2), aldolase (Aldoa), pyruvate kinase, muscle (Pkm), lactate dehydrogenase A (Ldha) and phosphofructokinase, liver, B-type (Pfkl). Quercetin also boosted the activity of PKM and LDHA, two crucial glycolytic enzymes. In summary, quercetin mitigates FB1-induced toxicity in TM4 cells by reducing ROS levels and enhancing glycolysis. This study offers new insights into preventing and treating FB1-induced toxic damage to the male reproductive system and highlights the potential application of quercetin. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aims Carbon source is a necessary nutrient for bacterial strain growth. In industrial production, the cost of using different carbon sources varies greatly. Moreover, the complex environment in space may cause metabolic a series of changes in the strain, and this method has been successfully applied in some basic research. To date, space mutagenesis is still limited number of studies, particularly in carbon metabolism of probiotics. Methods and results HG-R7970-41 was isolated from bacterium suspension (Probio-M9) after space flight, which can produce capsular polysaccharide after space mutagenesis. Phenotype Microarray (PM) was used to evaluated the metabolism of HG-R7970-41 in 190 single carbon sources. RNA sequencing and total protein identification of two strains revealed their different carbon metabolism mechanisms. PM results demonstrated the metabolism of 10 carbon sources were different between Probio-M9 and HG-R7970-41. Transcriptomic and proteomic analyses revealed that this change in carbon metabolism of HG-R7970-41 mainly related to changes in phosphorylation and the glycolysis pathway. Based on the metabolic mechanism of different carbon sources and related gene cluster analysis, we found that the final metabolic activities of HG-R7970-41 and Probio-M9 were mainly regulated by PTS-specific membrane embedded permease, carbohydrate kinase and two rate-limiting enzymes (phosphofructokinase and pyruvate kinase) in the glycolysis pathway. The expanded culture test also confirmed that HG-R7970-41 had different metabolic characteristics from original strain. Conclusions These results suggested that space environment could change carbon metabolism of Probio-M9. The new isolate (HG-R7970-41) showed a different carbon metabolism pattern from the original strain mainly by the regulation of two rate-limiting enzymes. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to identify candidate genes that play important roles in skeletal muscle development in ducks. Methods: In this study, we investigated the transcriptional sequencing of embryonic pectoral muscles from two specialized lines: Liancheng white ducks (female) and Cherry valley ducks (male) hybrid Line A (LCA) and Line C (LCC) ducks. In addition, prediction of target genes for the differentially expressed mRNAs was conducted and the enriched gene ontology (GO) terms and Kyoto encyclopedia of genes and genomes signaling pathways were further analyzed. Finally, a protein-to-protein interaction network was analyzed by using the target genes to gain insights into their potential functional association. Results: A total of 1,428 differentially expressed genes (DEGs) with 762 being up-regulated genes and 666 being down-regulated genes in pectoral muscle of LCA and LCC ducks identified by RNA-seq (p<0.05). Meanwhile, 23 GO terms in the down-regulated genes and 75 GO terms in up-regulated genes were significantly enriched (p<0.05). Furthermore, the top 5 most enriched pathways were ECM-receptor interaction, fatty acid degradation, pyruvate degradation, PPAR signaling pathway, and glycolysis/gluconeogenesis. Finally, the candidate genes including integrin b3 (Itgb3), pyruvate kinase M1/2 (Pkm), insulin-like growth factor 1 (Igf1), glucose-6-phosphate isomerase (Gpi), GABA type A receptor-associated protein-like 1 (Gabarapl1), and thyroid hormone receptor beta (Thrb) showed the most expression difference, and then were selected to verification by quantitative real-time polymerase chain reaction (qRT-PCR). The result of qRT-PCR was consistent with that of transcriptome sequencing. Conclusion: This study provided information of molecular mechanisms underlying the developmental differences in skeletal muscles between specialized duck lines. [ABSTRACT FROM AUTHOR]

The effect of hypoxia on the level of expression of pyruvate kinase (PKM), octopine dehydrogenase (OcDH), and malate dehydrogenase (MDH) genes in the gill tissue of the Mediterranean mussel Mytilus galloprovincialis (L., 1819) was studied experimentally. The control group of mollusks was kept at 9–10°C, and the oxygen level in the water was 8.5 mg O2 L–1. The experimental levels were at 9–10°C and 2.2 mg O2 L–1. The exposure was 24 and 72 h. Some of the individuals were subsequently subjected to the reoxygenation procedure. Under conditions of hypoxia, the expression level of OcDH and MDH genes increased by three and two times, respectively (p < 0.05). At the same time, OcDH expression showed sensitivity to the oxygen content in the medium. Under the conditions of reoxygenation, the process was completely suppressed. The expression of the PKM gene, on the contrary, did not depend on hypoxic effects and remained at the level of the control values. [ABSTRACT FROM AUTHOR]

Summary: Pyruvate kinase (PK) deficiency, a rare, congenital haemolytic anaemia caused by mutations in the PKLR gene, is associated with many clinical manifestations, but the full disease burden has yet to be characterised. The Peak Registry (NCT03481738) is an observational, longitudinal registry of adult and paediatric patients with PK deficiency. Here, we described comorbidities and complications in these patients by age at most recent visit and PKLR genotype. As of 13 May 2022, 241 patients were included in the analysis. In total, 48.3% had undergone splenectomy and 50.5% had received chelation therapy. History of iron overload (before enrolment/during follow‐up) was common (52.5%), even in never‐transfused patients (20.7%). Neonatal complications and symptoms included jaundice, splenomegaly and hepatomegaly, with treatment interventions required in 41.5%. Among adults, osteopenia/osteoporosis occurred in 19.0% and pulmonary hypertension in 6.7%, with median onset ages of 37, 33 and 22 years, respectively. Biliary events and bone health problems were common across PKLR genotypes. Among 11 patients who had thromboembolic events, eight had undergone prior splenectomy. Patients with PK deficiency may have many complications, which can occur early in and throughout life. Awareness of their high disease burden may help clinicians better provide appropriate monitoring and management of these patients. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is well established that pyruvate kinase M2 (PKM2) activity contributes to metabolic reprogramming in various cancers, including colorectal cancer (CRC). Estrogen or 17β‐estradiol (E2) signaling is also known to modulate glycolysis markers in cancer cells. However, whether the inhibition of PKM2 combined with E2 treatment could adversely affect glucose metabolism in CRC cells remains to be investigated. First, we confirmed the metabolic plasticity of CRC cells under varying environmental conditions. Next, we identified glycolysis markers that were upregulated in CRC patients and assessed in vitro mRNA levels following E2 treatment. We found that PKM2 expression, which is highly upregulated in CRC clinical samples, is not altered by E2 treatment in CRC cells. In this study, glucose uptake, generation of reactive oxygen species (ROS), lactate production, cell viability, and apoptosis were evaluated in CRC cells following E2 treatment, PKM2 silencing, or a combination of both. Compared to individual treatments, combination therapy resulted in a significant reduction in cell viability and enhanced apoptosis. Glucose uptake and ROS production were markedly reduced in PKM2‐silenced E2‐treated cells. The data presented here suggest that E2 signaling combined with PKM2 inhibition cumulatively targets glucose metabolism in a manner that negatively impacts CRC cell growth. These findings hold promise for novel therapeutic strategies targeting altered metabolic pathways in CRC. Highlights: Colorectal cancer (CRC) cells exhibit a versatile metabolic profile that is responsive to changes in the tumor microenvironment.Estrogen (E2) signaling modulates glycolysis and reduces CRC cell growth and survival.Pyruvate kinase M2 (PKM2) inhibition also modulates glycolysis and reduces CRC cell growth.Combining E2 treatment with PKM2 inhibition precipitates significant cumulative antitumor effects in CRC cells. [ABSTRACT FROM AUTHOR]

During field surveys and culture procedures, large growth disparities in Anguilla japonica have been observed. However, the potential causes are unknown. This study explored differences in digestive ability, metabolic levels, and transcriptomic profiles of appetite-related genes between growth-retarded eel (GRE) and normal-growing eel (NGE) under the same rearing conditions. The results showed that growth hormone (gh) mRNA expression in GREs was considerably lower than NGEs. The levels of total protein (TP), total cholesterol (T-CHO), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), blood ammonia (BA), blood urea nitrogen (BUN), and alkaline phosphatase (ALP) in GREs were significantly lower than in NGEs. Conversely, levels of glucose (GLU), alanine aminotransferase (ALT), and aspartate transaminase (AST) were higher in GREs. The activities of SOD, CAT, and T-AOC levels were also significantly lower in GREs, as were the activities of glucose-related enzymes including hexokinase (HK), pyruvate kinase (PK), phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase (G6PASE). Additionally, orexigenic genes (npy and ghrelin) were dramatically downregulated, whereas anorexigenic genes (crh and pyy) were significantly upregulated in GREs. These findings suggested that variances in growth hormone, metabolic activities, and appetite level could be associated with the different growth rates of A. japonica. The present research not only revealed the characteristics of the growth, metabolism, and appetite of GREs but also offered new perspectives into the substantial growth discrepancies in A. japonica, providing novel ideas for enhancing fish growth. [ABSTRACT FROM AUTHOR]

BackgroundResistance to existing therapies is a significant challenge in improving outcomes for glioblastoma (GBM) patients. Metabolic plasticity has emerged as an important contributor to therapy resistance, including radiation therapy (RT). Here, we investigated how GBM cells reprogram their glucose metabolism in response to RT to promote radiation resistance.MethodsEffects of radiation on glucose metabolism of human GBM specimens were examined in vitro and in vivo with the use of metabolic and enzymatic assays, targeted metabolomics, and FDG-PET. Radiosensitization potential of interfering with M2 isoform of pyruvate kinase (PKM2) activity was tested via gliomasphere formation assays and in vivo human GBM models.ResultsHere, we show that RT induces increased glucose utilization by GBM cells, and this is accompanied with translocation of GLUT3 transporters to the cell membrane. Irradiated GBM cells route glucose carbons through the pentose phosphate pathway (PPP) to harness the antioxidant power of the PPP and support survival after radiation. This response is regulated in part by the PKM2. Activators of PKM2 can antagonize the radiation-induced rewiring of glucose metabolism and radiosensitize GBM cells in vitro and in vivo.ConclusionsThese findings open the possibility that interventions designed to target cancer-specific regulators of metabolic plasticity, such as PKM2, rather than specific metabolic pathways, have the potential to improve the radiotherapeutic outcomes in GBM patients.

The postmortem conversion of muscle to meat goes through a series of complex physiological and biochemical changes, among which protein post-translational modifications (PTMs) are key factors affecting meat quality. Glycolysis is the major energy supply pathway in postmortem muscle. PTMs can change the function and structure of pyruvate kinase, a rate-limiting enzyme in the glycolytic pathway, which can in turn affect meat quality. Beginning with an overview of the structure and function of pyruvate kinase, this article reviews the recent research progress on the effects of PTMs of pyruvate kinase on its function and structure and the effects of pyruvate kinase phosphorylation, acetylation and S-nitrosylation on meat quality.

Growing evidence suggests that metabolic regulation directly influences cellular function and development and thus may be more dynamic than previously expected. In vivo and in real-time analysis of metabolite activities during development is crucial to test this idea directly. In this study, we employ two metabolic biosensors to track the dynamics of pyruvate and oxidative phosphorylation (Oxphos) during the early embryogenesis of the sea urchin. A pyruvate sensor, PyronicSF, shows the signal enrichment on the mitotic apparatus, which is consistent with the localization patterns of the corresponding enzyme, pyruvate kinase (PKM). The addition of pyruvate increases the PyronicSF signal, while PKM knockdown decreases its signal, responding to the pyruvate level in the cell. Similarly, a ratio-metric sensor, Grx-roGFP, that reads the redox potential of the cell responds to DTT and H 2 O 2 , the known reducer and inducer of Oxphos. These observations suggest that these metabolic biosensors faithfully reflect the metabolic status in the cell during embryogenesis. The time-lapse imaging of these biosensors suggests that pyruvate and Oxphos levels change both spatially and temporarily during embryonic development. Pyruvate level is increased first in micromeres compared to other blastomeres at the 16-cell stage and remains high in ectoderm while decreasing in endomesoderm during gastrulation. In contrast, the Oxphos signal first decreases in micromeres at the 16-cell stage, while it increases in the endomesoderm during gastrulation, showing the opposite trend of the pyruvate signal. These results suggest that metabolic regulation is indeed both temporally and spatially dynamic during embryogenesis, and these biosensors are a valuable tool to monitor metabolic activities in real-time in developing embryos. • PKM and pyruvate localize on the spindle and in the nucleus during early embryogenesis of the sea urchin. • Pyruvate is increased in micromeres, while Oxidative phosphorylation is decreased in micromeres. • Pyruvate and Oxidative phosphorylation sensors show an opposite trend of expression dynamics during embryogenesis. • Metabolic biosensors are valuable tools for analyzing in vivo metabolic regulation in developing embryos. [ABSTRACT FROM AUTHOR]

Objective: Finding biomarkers related to non-small cell lung cancer (NSCLC) is helpful for the diagnosis and precise treatment of lung cancer. The relationship between serum tumor M2-pyruvate kinase (TuM2-PK), carcinoembryonic antigen (CEA), and cytokeratin 19 fragment (CYFRA21-1) and NSCLC was analyzed. Methods: The serum levels of TuM2-PK, CEA, and CYFRA21-1 in 184 patients with the NSCLC group, 60 patients with the benign lung disease (BLD) group, and 90 healthy controls (HC) group were detected. The levels of TuM2-PK were measured by using an enzyme-linked immunosorbent assay. The detection methods of CEA and CYFRA21-1 were electrochemiluminescence. The receiver operating characteristic (ROC) curve was drawn to evaluate the diagnostic value of TuM2-PK, CEA, and CYFRA21-1 on NSCLC. The Kaplan–Meier survival curve was drawn to evaluate the survival status in NSCLC patients with different serum levels of TuM2-PK, CEA, and CYFRA21-1. Results: Serum levels of TuM2-PK, CEA, and CYFRA21-1 in the NSCLC group were significantly higher than those in the BLD group and the HC group (P <.01). Serum levels of TuM2-PK, CEA, and CYFRA21-1 in NSCLC patients were associated with the tumor lymph node metastasis stage (P <.05), lymph node metastasis (P <.05), and distant metastasis (P <.05). The ROC curve showed that the area under the curve of serum levels of TuM2-PK, CEA, and CYFRA21-1 was 0.814, 0.638, and 0.719, respectively, and that the combination of the above 3 was 0.918. The Kaplan–Meier survival curve showed that the 1-, 3- and 5-year survival rate in NSCLC patients with positive TuM2-PK, CEA, and CYFRA21-1 was significantly lower than that in NSCLC patients with negative TuM2-PK, CEA, and CYFRA21-1, respectively (P <.05). Conclusions: Serum TuM2-PK, CEA, and CYFRA21-1 levels have high clinical values in the diagnosis of NSCLC, and can effectively judge the prognosis of patients. [ABSTRACT FROM AUTHOR]

Metabolic dysfunction-associated fatty liver disease (MAFLD) presents a significant global health challenge, characterized by the accumulation of liver fat and impacting a considerable portion of the worldwide population. Despite its widespread occurrence, effective treatments for MAFLD are limited. The liver-specific isoform of pyruvate kinase (PKL) has been identified as a promising target for developing MAFLD therapies. Urolithin C, an allosteric inhibitor of PKL, has shown potential in preliminary studies. Expanding upon this groundwork, our study delved into delineating the structure-activity relationship of urolithin C via the synthesis of sulfone-based urolithin analogs. Our results highlight that incorporating a sulfone moiety leads to substantial PKL inhibition, with additional catechol moieties further enhancing this effect. Despite modest improvements in liver cell lines, there was a significant increase in inhibition observed in HepG2 cell lysates. Specifically, compounds 15d, 9d, 15e, 18a, 12d, and 15a displayed promising IC50 values ranging from 4.3 µM to 18.7 µM. Notably, compound 15e not only demonstrated a decrease in PKL activity and triacylglycerol (TAG) content but also showed efficient cellular uptake. These findings position compound 15e as a promising candidate for pharmacological MAFLD treatment, warranting further research and studies. [ABSTRACT FROM AUTHOR]

Mitapivat is a novel, first‐in‐class orally active pyruvate kinase activator approved by the US Food and Drug Administration in 2022 for the treatment of hemolytic anemia. There is no literature available regarding the identification of degradation impurities of mitapivat. The present study deals with the degradation behavior of mitapivat under various stress conditions such as hydrolytic, photolytic, thermal, and oxidative stress. The multivariate analysis found that the independent variables, that is, molarity, temperature, and time, are interacting with each other to affect the degradation of mitapivat. A specific, accurate, and precise high‐performance liquid chromatographic (HPLC) method was developed to separate mitapivat from its degradation products. The separation was achieved on the C‐18 column (250 mm × 4.6 mm × 5 µm) using the combination of 0.1% formic acid buffer and acetonitrile in gradient elution profile. The method was validated as per the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use Q2(R2) guideline. LC‐electrospray ionization‐Quadrupole‐time of flight was employed to identify degradation products. A total of seven novel degradation products of mitapivat were identified based on tandem mass spectrometry and accurate mass measurement. In‐silico toxicity of mitapivat and its degradation products was qualitatively evaluated by the DEREK toxicity prediction tool. [ABSTRACT FROM AUTHOR]

NAD-dependent deacetylase Sirt2 is involved in mammalian metabolic activities, matching energy demand with energy production and expenditure, and is relevant to a variety of metabolic diseases. Here, we constructed Sirt2 knockout and adeno-associated virus overexpression mice and found that deletion of hepatic Sirt2 accelerated primary obesity and insulin resistance in mice with concomitant hepatic metabolic dysfunction. However, the key targets of Sirt2 are unknown. We identified the M2 isoform of pyruvate kinase (PKM2) as a key Sirt2 target involved in glycolysis in metabolic stress. Through yeast two-hybrid and mass spectrometry combined with multi-omics analysis, we identified candidate acetylation modification targets of Sirt2 on PKM2 lysine 135 (K135). The Sirt2-mediated deacetylation-ubiquitination switch of PKM2 regulated the development of glycolysis. Here, we found that Sirt2 deficiency led to impaired glucose tolerance and insulin resistance and induced primary obesity. Sirt2 severely disrupted liver function in mice under metabolic stress, exacerbated the metabolic burden on the liver, and affected glucose metabolism. Sirt2 underwent acetylation modification of lysine 135 of PKM2 through a histidine 187 enzyme active site-dependent effect and reduced ubiquitination of the K48 ubiquitin chain of PKM2. Our findings reveal that the hepatic glucose metabolism links nutrient state to whole-body energetics through the rhythmic regulation of Sirt2. [ABSTRACT FROM AUTHOR]

Glioblastomas (GBMs) are characterized by high heterogeneity, involving diverse cell types, including those with stem‐like features contributing to GBM's malignancy. Moreover, metabolic alterations promote growth and therapeutic resistance of GBM. Depending on the metabolic state, antimetabolic treatments could be an effective strategy. Against this background, we investigated temporal and regional expression changes and co‐staining patterns of selected metabolic markers [pyruvate kinase muscle isozyme 1/2 (PKM1/2), glucose transporter 1 (GLUT1), monocarboxylate transporter 1/4 (MCT1/4)] in a rodent model and patient‐derived samples of GBM. To understand the cellular sources of marker expression, we also examined the connection of metabolic markers to markers related to stemness [Nestin, Krüppel‐like factor 4 (KLF4)] in a regional and temporal context. Rat tumour biopsies revealed a temporally increasing expression of GLUT1, higher expression of MCT1/4, Nestin and KLF4, and lower expression of PKM1 compared to the contralateral hemisphere. Patient‐derived tumours showed a higher expression of PKM2 and Nestin in the tumour centre vs. edge. Whereas rare co‐staining of GLUT1/Nestin was found in tumour biopsies, PKM1/2 and MCT1/4 showed a more distinct co‐staining with Nestin in rats and humans. KLF4 was mainly co‐stained with GLUT1, MCT1 and PKM1/2 in rat and human tumours. All metabolic markers yielded individual co‐staining patterns among themselves. Co‐staining mainly occurred later in tumour progression and was more pronounced in tumour centres. Also, positive correlations were found amongst markers that showed co‐staining. Our results highlight a link between metabolic alterations and stemness in GBM progression, with complex distinctions depending on studied markers, time points and regions. [ABSTRACT FROM AUTHOR]

Summary: Pyruvate kinase (PK) is a key enzyme of anaerobic glycolysis. The genetic heterogeneity of PK deficiency (PKD) is high, and over 400 unique variants have been identified. Twenty‐nine patients who had been diagnosed as PKD genetically in seven distinct paediatric haematology departments were evaluated. Fifteen of 23 patients (65.2%) had low PK levels. The PK:hexokinase ratio had 100% sensitivity for PKD diagnosis, superior to PK enzyme assay. Two novel intronic variants (c.695‐1G>A and c.694+43C>T) have been described. PKD should be suspected in patients with chronic non‐spherocytic haemolytic anaemia, even if enzyme levels are falsely normal. Total PKLR gene sequencing is necessary for the characterization of patients with PKD and for genetic counselling. [ABSTRACT FROM AUTHOR]

AIM: To clarify the effect of macrophage PKM2 deficiency on mucosal repair in ulcerative colitis (UC). METHODS: The gene expression and metabolic profiles in UC patients were first analyzed based on the following databases: PXD001608, GSE193677, and GSE214695. Using the macrophage-specific PKM2 elimination mice (PKM2AMAC), the functions of PKM2 in dextran sulfate sodium (DSS)-induced UC were clarified in vivo by analyzing the body weight, disease activity index (DAI) scores, HE staining, immunohistochemical staining, and expression of mucosal barrier markers. The impact of PKM2 on macrophage polarization was also investigated by flow cytometry, RNA sequencing and RT-qPCR in mouse bone marrow-derived macrophages (BMDMs) and THP-1 cells in vitro. RESULTS: Bioinformatic analysis suggested that the intestinal tissues of UC patients preferred glycolysis. The expression of PKM was parallel to the severity of UC in patients, and the expression of PKM2, but not PKM1, was elevated in macrophages of UC mice. In the DSS-induced UC mice, macrophage-specific PKM2 elimination significantly alleviates the body weight loss, diarrhea, rectal bleeding, colonic shorten, as well as decreased DAI scores and mucosal tissue damage. The BMDMs derived from the PKM2ΔMAC mice preferred the M2 polarization upon LPS or IL-4 stimulation to that derived from the wild-type mice, as indicated by the F4/80+ CD45+ CD86+ and F4/80+ CD45+ CD206+ population, as well as the expression of Ocln, F11r and Tjp-1. The RNA sequencing results indicated significant gene differential expression in PKM2 knockout mouse macrophages, which was enriched in biological processes such as leukocyte migration, tissue remodeling, and cytokine interactions. Macrophage PKM2 deficiency promoted the expression of mucosal repair factors (118, Cxcl1, Ptgs2 and Wnt6, which was further validated in PKM2 knockout THP-1 cells. CONCLUSION: The PKM2 deficiency in macrophages benifits the mucosal repair in UC status via facilitating the wound-healing macrophage polarization. [ABSTRACT FROM AUTHOR]

The 'Feizixiao' litchi cultivar, predominantly grown in Hainan Province, faces the issue of "sugar receding" during fruit ripening. The application of mixed foliar nutrients containing calcium and magnesium (Ca+Mg) during the fruit pericarp's full coloring stage was investigated to overcome this issue. Experimental trials unveiled significant alterations in litchi pulp physiochemical properties, including the main nutrient and flavor quality, the total respiration rates of the main respiratory pathways, and the activities of some important enzymes associated with Embden–Meyerhof–Parnas (EMP), the tricarboxylic acid cycle (TCA) and the pentose phosphate pathway (PPP). The Ca+Mg treatment showed higher sugar levels than the control (CK) during ripening. Notably, the application of Ca+Mg in litchi pulp inhibited respiration rates through the EMP, TCA, and PPP pathways, resulting in a strong effect. RNA sequencing analysis revealed the impact of Ca+Mg treatment on respiratory pathways, revealing differentially expressed genes (DEGs) such as pyruvate PK1, PK2 (pyruvate kinase), and PDC (pyruvate dehydrogenase complex), validated through qRT-PCR with a significant correlation to RNA-seq results. In general, Ca+Mg treatment during litchi fruit ripening overcame "sugar receding" by inhibiting the expression of respiration key metabolic pathway genes. These findings provide insights for enhancing cultivation management strategies. [ABSTRACT FROM AUTHOR]

Metabolic engineering for high productivity and increased robustness is needed to enable sustainable biomanufacturing of lactic acid from lignocellulosic biomass. Lactic acid is an important commodity chemical used for instance as a monomer for production of polylactic acid, a biodegradable polymer. Here, rational and model-based optimization was used to engineer a diploid, xylose fermenting Saccharomyces cerevisiae strain to produce L-lactic acid. The metabolic flux was steered towards lactic acid through the introduction of multiple lactate dehydrogenase encoding genes while deleting ERF2 , GPD1 , and CYB2. A production of 93 g/L of lactic acid with a yield of 0.84 g/g was achieved using xylose as the carbon source. To increase xylose utilization and reduce acetic acid synthesis, PHO13 and ALD6 were also deleted from the strain. Finally, CDC19 encoding a pyruvate kinase was overexpressed, resulting in a yield of 0.75 g lactic acid/g sugars consumed, when the substrate used was a synthetic lignocellulosic hydrolysate medium, containing hexoses, pentoses and inhibitors such as acetate and furfural. Notably, modeling also provided leads for understanding the influence of oxygen in lactic acid production. High lactic acid production from xylose, at oxygen-limitation could be explained by a reduced flux through the oxidative phosphorylation pathway. On the contrast, higher oxygen levels were beneficial for lactic acid production with the synthetic hydrolysate medium, likely as higher ATP concentrations are needed for tolerating the inhibitors therein. The work highlights the potential of S. cerevisiae for industrial production of lactic acid from lignocellulosic biomass. [Display omitted] • A xylose fermenting S. cerevisiae strain was engineered to produce L-lactic acid. • Rational and model-guided design was applied to increase lactic acid production. • 93 g/L of lactic acid at a yield of 0.84 g/g was produced from xylose. • A yield of 0.75 g/g was achieved in a synthetic lignocellulosic hydrolysate. • Modeling was used to understand the influence of oxygen in lactic acid production. [ABSTRACT FROM AUTHOR]

In this study, a genetic linkage map was developed based on simple sequence repeat (SSR) markers to aid in the identification and expression analysis of gene loci underlying the quantitative trait loci (QTL) of starch content (SC) in cassava (Manihot esculenta). A total of 912 polymorphic loci from 4,515 tested SSRs were mapped into 18 linkage groups. QTL analysis revealed four loci with highly significant associations with starch. Gene annotation was performed, and potential genes related to starch synthesis were identified. Of these, expression of four genes related to starch synthesis (Raffinose synthase [RS], Phosphoenolpyruvate kinase [PK], Glucose-6-phosphate [G6P], and Glycogen synthase kinase 3 [GSK-3]) was investigated by real-time PCR assays. The results found a statistically significant difference (p < 0.05) at 3 months after planting (MAP) in all the tested genes, whereas a higher expression was detected in the low-SC group with specific genotypes of linked markers. A higher level of expression was observed in the RS, PK, and G6P genes at six and nine MAP, indicating that starch accumulation mainly occurs after 3 MAP, during which the root system begins to form. The potential genes identified in this study could provide a better understanding of the starch biosynthesis mechanism, and could be useful for applications in marker-assisted selection to facilitate cassava breeding programs in the future. [ABSTRACT FROM AUTHOR]

Recombinase polymerase amplification (RPA) is an isothermal DNA amplification reaction at around 41 °C using recombinase (Rec), single-stranded DNA-binding protein (SSB), strand-displacing DNA polymerase (Pol), and an ATP-regenerating enzyme. Considering the onsite use of RPA reagents, lyophilized RPA reagents with long storage stability are highly desired. In this study, as one of the approaches to solve this problem, we attempted to use a thermostable pyruvate kinase (PK). PK gene was isolated from a thermophilic bacterium Thermotoga maritima (Tma -PK). Tma -PK was expressed in Escherichia coli and purified from the cells. Tma -PK exhibited higher thermostability than human PK. The purified Tma -PK preparation was applied to RPA as an ATP-regenerating enzyme. Liquid RPA reagent with Tma -PK exhibited the same performance as that with human PK. Lyophilized RPA reagent with Tma -PK exhibited higher performance than that with human PK. Combined with our previous results of RPA reagents of thermostable Pol from a thermophilic bacterium, Aeribacillus pallidus , the results in this study suggest that thermostable enzymes are preferable to mesophilic ones as a component in lyophilized RPA reagents. [ABSTRACT FROM AUTHOR]

Glioma is a common intracranial tumor, exhibiting a high degree of aggressiveness and invasiveness. Pyruvate kinase M2 (PKM2) is overexpressed in glioma tissues. However, the biological role of PKM2 in glioma is unclear. The qRT-PCR, CCK-8, Transwell, flow cytometry detection, western blot assays, ELISA assay, and pyruvate kinase activity assays were performed in glioma cells transfected with PKM2 shRNA to explore the function of PKM2 in glioma progression. Then, STRING website was used to predict the proteins that interacted with PKM2, and Co-IP assay was conducted to further validate their interaction. Subsequently, the above experiments were performed again to find the effect of catenin beta 1 (CTNNB1) overexpression on PKM2-deficient glioma cells. The transplanted tumor models were also established to further validate our findings. PKM2 was up-regulated in glioma cells and tissues. After inhibiting PKM2, the proliferation, migration, glycolysis, and EMT of glioma cells were significantly decreased, and the proportion of apoptosis was increased. The prediction results of STRING website showed that CTNNB1 and PKM2 had the highest interaction score. The correlation between CTNNB1 and PKM2 was further confirmed by Co-IP test. PKM2 knockdown suppressed glioma cell proliferation, migration, glycolysis, and EMT, while CTNNB1 overexpression rescued these inhibitory effects. Correspondingly, PKM2 knockdown inhibited glioma growth in vivo. In summary, these findings indicated that PKM2 promotes glioma progression by mediating CTNNB1 expression, providing a possible molecular marker for the clinical management of gliomas. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of sevoflurane (Sev) on nasopharyngeal carcinoma (NPC) in malignant behavior and mitochondrial membrane potential (MMP). NPC cells (5-8F and CNE2) were exposed to Sev at different concentrations and then tested for proliferation by CCK-8 and colony formation assays, apoptosis by flow cytometry, and invasion and migration by Transwell assays. In addition, the Warburg effect was examined by measurements of glucose consumption, lactic acid production, and adenosine triphosphate (ATP). Mitochondrial function was evaluated by reactive oxygen species (ROS) production, oxidative stress-related indexes, and mitochondrial membrane potential. Sev suppressed 5-8F and CNE2 cell proliferation, invasion, and migration, and enhanced apoptosis. Moreover, Sev dampened the Warburg effect by reducing glucose consumption, lactic acid production, and ATP, as well as decreasing hexokinase 2 and pyruvate kinases type M2 protein expressions. Also, Sev induced ROS production and malondialdehyde content and reduced superoxide and glutathione peroxidase levels. Finally, Sev caused damage to mitochondrial homeostasis through induction of cleaved caspase-3, cleaved caspase-9, and cytochrome c protein expression and reduction of MMP. Sev inhibits the malignant behavior of NPC cells by regulating MMP. [ABSTRACT FROM AUTHOR]

Rheostat positions, which can be substituted with various amino acids to tune protein function across a range of outcomes, are a developing area for advancing personalized medicine and bioengineering. Current methods cannot accurately predict which proteins contain rheostat positions or their substitution outcomes. To compare the prevalence of rheostat positions in homologs, we previously investigated their occurrence in two pyruvate kinase (PYK) isozymes. Human liver PYK contained numerous rheostat positions that tuned the apparent affinity for the substrate phosphoenolpyruvate (Kapp‐PEP) across a wide range. In contrast, no functional rheostat positions were identified in Zymomonas mobilis PYK (ZmPYK). Further, the set of ZmPYK substitutions included an unusually large number that lacked measurable activity. We hypothesized that the inactive substitution variants had reduced protein stability, precluding detection of Kapp‐PEP tuning. Using modified buffers, robust enzymatic activity was obtained for 19 previously‐inactive ZmPYK substitution variants at three positions. Surprisingly, both previously‐inactive and previously‐active substitution variants all had Kapp‐PEP values close to wild‐type. Thus, none of the three positions were functional rheostat positions, and, unlike human liver PYK, ZmPYK's Kapp‐PEP remained poorly tunable by single substitutions. To directly assess effects on stability, we performed thermal denaturation experiments for all ZmPYK substitution variants. Many diminished stability, two enhanced stability, and the three positions showed different thermal sensitivity to substitution, with one position acting as a "stability rheostat." The differences between the two PYK homologs raises interesting questions about the underlying mechanism(s) that permit functional tuning by single substitutions in some proteins but not in others. [ABSTRACT FROM AUTHOR]

Organic acids play critical roles in fruit physiological metabolism and sensory quality. However, the conventional storage of apple fruit at 0 ± 0.1 °C cannot maintain fruit acidity efficiently. This study investigated near-freezing temperature (NFT) storage for 'Golden Delicious' apples, and the quality parameters, organic acid content, and malate metabolism were studied. The results indicate that NFT storage at −1.7 ± 0.1 °C effectively maintained the postharvest quality of apple fruit when compared to traditional storage at 0 ± 0.1 °C. Fruit that underwent NFT storage showed a better appearance and lower respiratory rate, ethylene production, weight loss, and malondialdehyde (MDA) content but higher firmness and soluble solids content. Further, fruit after NFT storage contained higher titratable acid (18.75%), malate (51.61%), citrate (36.59%), and succinate (2.12%) content when compared to the control after 250 days. This was achieved by maintaining higher cytosolic NAD-dependent malate dehydrogenase (cyNAD-MDH), phosphoenolpyruvate carboxylase (PEPC), vacuolar H+-ATPase (V-ATPase), and vacuolar inorganic pyrophosphatase (V-PPase) activities that promote malate biosynthesis and accumulation while inhibiting enzyme activity that is responsible for malate decomposition, including phosphoenolpyruvate carboxylase kinase (PEPCK) as well as the cytosolic NAD phosphate-dependent malic enzyme (cyNADP-ME). Further, storage at NFTs maintained a higher expression of malate biosynthesis-related genes (MdcyNAD-MDH and MdPEPC) and transport-related genes (MdVHA and MdVHP) while suppressing malate consumption-related genes (MdcyME and MdPEPCK). The results demonstrate that NFT storage could be an effective application for apple fruit, which maintains postharvest quality and alleviates organic acid degradation. [ABSTRACT FROM AUTHOR]

Efficient distribution of oxygen (O2) to the tissues in mammals depends on the evolved ability of red blood cell (RBC) hemoglobin (Hb) to sense not only O2 levels, but metabolic cues such as pH, PCO2, and organic phosphates, and then dispense or take up oxygen accordingly. O2 delivery is the product of not only oxygen release fromRBCs, but also blood flow,which itself is also governed by vasoactivemolecular mediators exported by RBCs. These vascular signals, including ATP and S-nitrosothiols (SNOs) are produced and exported as a function of the oxygen and metabolic milieu, and then fine-tune peripheral metabolism through context-sensitive vasoregulation. Emerging and repurposed RBC-oriented therapeutics can modulate either or both of these allosteric and vasoregulatory activities, with a single molecule or other intervention influencing both arms of O2 transport in some cases. For example, organic phosphate repletion of stored RBCs boosts the negative allosteric effector 2,3 biphosphoglycerate (BPG) as well as the anti-adhesive molecule ATP. In sickle cell disease, aromatic aldehydes such as voxelotor can disfavor sickling by increasing O2 affinity, and in newer generations, these molecules have been coupled to vasoactive nitric oxide (NO)-releasing adducts. Activation of RBC pyruvate kinase also promotes a left shift in oxygen binding by consuming and lowering BPG, while increasing the ATP available for cell health and export on demand. Further translational and clinical investigation of these novel allosteric and/or vasoregulatory approaches to modulating O2 transport are expected to yield new insights and improve the ability to correct or compensate for anemia and other O2 delivery deficits. [ABSTRACT FROM AUTHOR]

Pyruvate kinase M2 (PKM2), a rate limiting enzyme in glycolysis, is a cellular regulator that has received extensive attention and regards as a metabolic regulator of cellular metabolism and energy. Kidney is a highly metabolically active organ, and glycolysis is the important energy resource for kidney. The accumulated evidences indicates that the enzymatic activity of PKM2 is disturbed in kidney disease progression and treatment, especially diabetic kidney disease and acute kidney injury. Modulating PKM2 post-translational modification determines its enzymatic activity and nuclear translocation that serves as an important interventional approach to regulate PKM2. Emerging evidences show that PKM2 and its post-translational modification participate in kidney disease progression and treatment through modulating metabolism regulation, podocyte injury, fibroblast activation and proliferation, macrophage polarization, and T cell regulation. Interestingly, PKM2 activators (TEPP-46, DASA-58, mitapivat, and TP1454) and PKM2 inhibitors (shikonin, alkannin, compound 3k and compound 3h) have exhibited potential therapeutic property in kidney disease, which indicates the pleiotropic effects of PKM2 in kidney. In the future, the deep investigation of PKM2 pleiotropic effects in kidney is urgently needed to determine the therapeutic effect of PKM2 activator/inhibitor to benefit patients. The information in this review highlights that PKM2 functions as a potential biomarker and therapeutic target for kidney diseases. [ABSTRACT FROM AUTHOR]

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. Synopsis: The mechanistic contribution of phosphoglycerate mutase 1 (PGAM1), a metabolic enzyme active in glycolysis to tumorigenesis remains unclear. Here, PGAM1 activity is shown to be controlled by pyruvate kinase M2 (PKM2), promoting glycolytic shunts and macromolecule biosynthesis during metabolic reprogramming in cancer cells. PKM2 moonlights as a histidine kinase and phosphorylates PGAM1 at H11 by transferring phosphate from phosphoenolpyruvate. De-tetramerization is favorable for PKM2 functioning as a histidine kinase, but disadvantageous for its glycolytic activity. PGAM1 Y119 phosphorylation induced by EGF-Src signaling is required for PKM2 recognition and binding. A PGAM1-derived pY119-containing cell-permeable peptide blocks PGAM1-PKM2 interaction, thereby slowing down tumor growth. Non-canonical PKM2 function controls PGAM1 and macromolecule biosynthesis during metabolic reprogramming and tumor growth. [ABSTRACT FROM AUTHOR]

In recent years, researchers have often encountered the significance of the aberrant metabolism of tumor cells in the pathogenesis of malignant neoplasms. This phenomenon, known as the Warburg effect, provides a number of advantages in the survival of neoplastic cells, and its application is considered a potential strategy in the search for antitumor agents. With the aim of developing a promising platform for designing antitumor therapeutics, we synthesized a library of conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones. To gain insight into the determinants of the biological activity of the prepared compounds, we showed that the conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones, which are cytotoxic agents, demonstrate selective activity toward a number of tumor cell lines with glycolysis-inhibiting ability. Moreover, the results of molecular and in silico screening allowed us to identify these compounds as potential inhibitors of the pyruvate kinase M2 oncoprotein, which is the rate-determining enzyme of glycolysis. Thus, the results of our work indicate that the synthesized conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones can be considered a promising platform for designing selective cytotoxic agents against the glycolysis process, which opens new possibilities for researchers involved in the search for antitumor therapeutics among compounds containing piperidone platforms. [ABSTRACT FROM AUTHOR]

Pyruvate kinase is a glycolytic enzyme that converts phosphoenolpyruvate and ADP into pyruvate and ATP. There are two genes that encode pyruvate kinase in vertebrates; Pkm and Pkl encode muscle‐ and liver/erythrocyte‐specific forms, respectively. Each gene encodes two isoenzymes due to alternative splicing. Both muscle‐specific enzymes, PKM1 and PKM2, function in glycolysis, but PKM2 also has been implicated in gene regulation due to its ability to phosphorylate histone 3 threonine 11 (H3T11) in cancer cells. Here, we examined the roles of PKM1 and PKM2 during myoblast differentiation. RNA‐seq analysis revealed that PKM2 promotes the expression of Dpf2/Baf45d and Baf250a/Arid1A. DPF2 and BAF250a are subunits that identify a specific sub‐family of the mammalian SWI/SNF (mSWI/SNF) of chromatin remodeling enzymes that is required for the activation of myogenic gene expression during differentiation. PKM2 also mediated the incorporation of DPF2 and BAF250a into the regulatory sequences controlling myogenic gene expression. PKM1 did not affect expression but was required for nuclear localization of DPF2. Additionally, PKM2 was required not only for the incorporation of phosphorylated H3T11 in myogenic promoters but also for the incorporation of phosphorylated H3T6 and H3T45 at myogenic promoters via regulation of AKT and protein kinase C isoforms that phosphorylate those amino acids. Our results identify multiple unique roles for PKM2 and a novel function for PKM1 in gene expression and chromatin regulation during myoblast differentiation. [ABSTRACT FROM AUTHOR]

The endogenous mitochondrial quality control (MQC) system serves to protect mitochondria against cellular stressors. Although mitochondrial dysfunction contributes to cardiac damage during many pathological conditions, the regulatory signals influencing MQC disruption during septic cardiomyopathy (SC) remain unclear. This study aimed to investigate the involvement of pyruvate kinase M2 (PKM2) and prohibitin 2 (PHB2) interaction followed by MQC impairment in the pathogenesis of SC. We utilized LPS-induced SC models in PKM2 transgenic (PKM2TG) mice, PHB2S91D-knockin mice, and PKM2-overexpressing HL-1 cardiomyocytes. After LPS-induced SC, cardiac PKM2 expression was significantly downregulated in wild-type mice, whereas PKM2 overexpression in vivo sustained heart function, suppressed myocardial inflammation, and attenuated cardiomyocyte death. PKM2 overexpression relieved sepsis-related mitochondrial damage via MQC normalization, evidenced by balanced mitochondrial fission/fusion, activated mitophagy, restored mitochondrial biogenesis, and inhibited mitochondrial unfolded protein response. Docking simulations, co-IP, and domain deletion mutant protein transfection experiments showed that PKM2 phosphorylates PHB2 at Ser91, preventing LPS-mediated PHB2 degradation. Additionally, the A domain of PKM2 and the PHB domain of PHB2 are required for PKM2-PHB2 binding and PHB2 phosphorylation. After LPS exposure, expression of a phosphorylation-defective PHB2S91A mutant negated the protective effects of PKM2 overexpression. Moreover, knockin mice expressing a phosphorylation-mimetic PHB2S91D mutant showed improved heart function, reduced inflammation, and preserved mitochondrial function following sepsis induction. Abundant PKM2 expression is a prerequisite to sustain PKM2-PHB2 interaction which is a key element for preservation of PHB2 phosphorylation and MQC, presenting novel interventive targets for the treatment of septic cardiomyopathy. [ABSTRACT FROM AUTHOR]

Simple Summary: Boar sperm is a highly sensitive biological product, and its quality is susceptible to various environmental factors during transportation. Presently, vibration emissions were observed and documented during the transportation of artificial insemination doses. Vibrations, serving as an environmental stressor, harbor the potential to exert an influence on sperm quality. However, the precise mechanism underlying the detrimental effects of vibration emissions on sperm functionality remains elusive. In the present research, we discerned that vibration emissions impair the quality of boar sperm by modulating their metabolic processes, ultimately resulting in a diminished fertilization capability. Artificial insemination (AI) with liquid-preserved semen has recently become common in pig breeding. The semen doses are produced in a centralized manner at the boar stud and then subsequently distributed and transported to sow farms. However, vibration emissions during transportation by logistic vehicles may adversely affect the quality of boar sperm. Therefore, this study aimed to explore the impact of vibration-induced emissions on sperm quality and function under simulated transportation conditions. Each time, ejaculates from all 15 boars were collected and then pooled together to minimize individual variations, and the sample was split using an extender for dilution. Different rotational speeds (0 rpm, 80 rpm, 140 rpm, 200 rpm) were utilized to simulate varying intensities of vibration exposure using an orbital shaker, considering different transportation times (0 h, 3 h, and 6 h). Subsequently, evaluations were conducted regarding sperm motility, plasma membrane integrity, acrosome integrity, mitochondrial function, adenosine triphosphate (ATP) levels, mitochondrial reactive oxygen species (ROS) levels, pH, glycolytic pathway enzyme activities, and capacitation following exposure to vibration emissions. Both vibration time and intensity impact sperm motility, plasma membrane integrity, and acrosomal integrity. Vibration exposure significantly reduced sperm ATP levels, mitochondrial membrane potential, and the levels of mitochondria-encoded proteins (MT-ND1, MT-ND6) (p < 0.05). After vibration emission treatment, the pH value and mitochondrial ROS levels significantly increased (p < 0.05). Inhibition of sperm glycolysis was observed, with reduced activities of hexokinase (HK), pyruvate kinase (PK), and lactate dehydrogenase (LDH), along with decreased lactate levels (p < 0.05). Additionally, sperm tyrosine phosphorylation levels were significantly reduced by vibration emissions compared to the control group (p < 0.05). After the vibration emission treatment, the number of sperm bound to each square millimeter of oviduct explants decreased significantly compared to the control group (p < 0.05). Similarly, compared to the control group, using semen subjected to vibration stress for AI results in significantly reduced pregnancy rates, total born litter size, live-born litter size, and healthy born litter size (p < 0.05). [ABSTRACT FROM AUTHOR]

Purpose: The management of blepharitis continues to challenge clinicians due to the poorly understood aetiology of the condition. We recently identified the family of intracellular plakin proteins as essential driving forces underlying anterior blepharitis. A large‐scale protein analysis was used to study if a topical dexamethasone/tobramycin solution could be used to reverse the expression of plakin proteins. Methods: Tear film samples from treatment naïve patients with anterior blepharitis (n = 15) were collected with Schirmer filtration paper. A subgroup of the patients (n = 10) received treatment with a dexamethasone/tobramycin 1 + 3 mg/mL ophthalmic suspension (Tobradex®) for 3 weeks and collection of tear film samples was repeated. The samples were analysed with label‐free quantification nano liquid chromatography–tandem mass spectrometry requiring quantification in at least 70% of the samples in each group. Proteins were considered differentially expressed if p < 0.05. Results: Following Tobradex® intervention, 27 proteins were upregulated while 61 proteins were downregulated. Regulated proteins after Tobradex® treatment were involved in intermediate filament cytoskeleton organization including downregulation of the plakin proteins envoplakin, epiplakin and periplakin. Plectin, a protein of the plakin family, remained unchanged after Tobradex® therapy. Tobradex® treatment resulted in the regulation of proteins involved in translation including a cluster of downregulated ribosomal proteins. Tobradex® intervention was associated with the regulation of proteins involved in fructose metabolism and glycolytic processes including fructose‐1.6‐bisphosphatase 1, fructose‐bisphosphate aldolases A and B, pyruvate kinase PKM and transketolase. Ig lambda chain V‐I region, prominin‐1, and protein Niban were upregulated after Tobradex® treatment. Conclusions: Tobradex treatment reversed the expression of plakin proteins in anterior blepharitis. Topical solutions which inhibit the expression of plakin proteins may have the potential to restore the ocular surface integrity in anterior blepharitis and should be explored further. [ABSTRACT FROM AUTHOR]

This article, titled "Understanding the Structural and Functional Intricacies That Govern the Dynamic Regulation of Pyruvate Kinase Muscle Isoform 2(PKM2)," explores the role of PKM2 in cancer and aims to design PKM2 variants that can shift the equilibrium towards the tetramer form and negate its interaction with JMJD5, a positive tumorigenesis regulator. The study identifies critical residues at the dimer-tetramer interface of PKM2 and mutates them to create PKM2_DM. Biophysical characterization shows that PKM2_DM is well-folded and has higher stability compared to PKM2_WT. In silico scanning identifies the JMJD5-PKM2 interaction region, and further in-vitro validation is underway to disrupt this interaction. [Extracted from the article]

Rarely has a chemical elicited as much controversy as dichloroacetate (DCA). DCA was initially considered a dangerous toxic industrial waste product, then a potential treatment for lactic acidosis. However, the main controversies started in 2008 when DCA was found to have anti-cancer effects on experimental animals. These publications showed contradictory results in vivo and in vitro such that a thorough consideration of this compound's in cancer is merited. Despite 50 years of experimentation, DCA's future in therapeutics is uncertain. Without adequate clinical trials and health authorities' approval, DCA has been introduced in off-label cancer treatments in alternative medicine clinics in Canada, Germany, and other European countries. The lack of well-planned clinical trials and its use by people without medical training has discouraged consideration by the scientific community. There are few thorough clinical studies of DCA, and many publications are individual case reports. Case reports of DCA's benefits against cancer have been increasing recently. Furthermore, it has been shown that DCA synergizes with conventional treatments and other repurposable drugs. Beyond the classic DCA target, pyruvate dehydrogenase kinase, new target molecules have also been recently discovered. These findings have renewed interest in DCA. This paper explores whether existing evidence justifies further research on DCA for cancer treatment and it explores the role DCA may play in it. [ABSTRACT FROM AUTHOR]

The canonical model of glucose-induced increase in insulin secretion involves the metabolism of glucose via glycolysis and the citrate cycle, resulting in increased ATP synthesis by the respiratory chain and the closure of ATP-sensitive K+ (KATP) channels. The resulting plasma membrane depolarization, followed by Ca2+ influx through L-type Ca2+ channels, then induces insulin granule fusion. Merrins and colleagues have recently proposed an alternative model whereby KATP channels are controlled by pyruvate kinase, using glycolytic and mitochondrial phosphoenolpyruvate (PEP) to generate microdomains of high ATP/ADP immediately adjacent to KATP channels. This model presents several challenges. First, how mitochondrially generated PEP, but not ATP produced abundantly by the mitochondrial F1F0-ATP synthase, can gain access to the proposed microdomains is unclear. Second, ATP/ADP fluctuations imaged immediately beneath the plasma membrane closely resemble those in the bulk cytosol. Third, ADP privation of the respiratory chain at high glucose, suggested to drive alternating, phased-locked generation by mitochondria of ATP or PEP, has yet to be directly demonstrated. Finally, the approaches used to explore these questions may be complicated by off-target effects. We suggest instead that Ca2+ changes, well known to affect both ATP generation and consumption, likely drive cytosolic ATP/ADP oscillations that in turn regulate KATP channels and membrane potential. Thus, it remains to be demonstrated that a new model is required to replace the existing, mitochondrial bioenergetics–based model. [ABSTRACT FROM AUTHOR]

An agreed-upon consensus model of glucose-stimulated insulin secretion from healthy β-cells is essential for understanding diabetes pathophysiology. Since the discovery of the KATP channel in 1984, an oxidative phosphorylation (OxPhos)–driven rise in ATP has been assumed to close KATP channels to initiate insulin secretion. This model lacks any evidence, genetic or otherwise, that mitochondria possess the bioenergetics to raise the ATP/ADP ratio to the triggering threshold, and conflicts with genetic evidence demonstrating that OxPhos is dispensable for insulin secretion. It also conflates the stoichiometric yield of OxPhos with thermodynamics, and overestimates OxPhos by failing to account for established features of β-cell metabolism, such as leak, anaplerosis, cataplerosis, and NADPH production that subtract from the efficiency of mitochondrial ATP production. We have proposed an alternative model, based on the spatial and bioenergetic specializations of β-cell metabolism, in which glycolysis initiates insulin secretion. The evidence for this model includes that 1) glycolysis has high control strength over insulin secretion; 2) glycolysis is active at the correct time to explain KATP channel closure; 3) plasma membrane–associated glycolytic enzymes control KATP channels; 4) pyruvate kinase has favorable bioenergetics, relative to OxPhos, for raising ATP/ADP; and 5) OxPhos stalls before membrane depolarization and increases after. Although several key experiments remain to evaluate this model, the 1984 model is based purely on circumstantial evidence and must be rescued by causal, mechanistic experiments if it is to endure. [ABSTRACT FROM AUTHOR]