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Dysregulated macrophage responses and changes in tissue metabolism are hallmarks of chronic inflammation in the skin. However, the metabolic cues that direct and support macrophage functions in the skin are poorly understood. Here, we show that during sterile skin inflammation, the epidermis and macrophages uniquely depend on glycolysis and the TCA cycle, respectively. This compartmentalisation is initiated by ROS-induced HIF-1α stabilization leading to enhanced glycolysis in the epidermis. The end-product of glycolysis, lactate, is then exported by epithelial cells and utilized by the dermal macrophages to induce their M2-like fates through NF-κB pathway activation. In addition, we show that psoriatic skin disorder is also driven by such lactate metabolite-mediated crosstalk between the epidermis and macrophages. Notably, small-molecule inhibitors of lactate transport in this setting attenuate sterile inflammation and psoriasis disease burden, and suppress M2-like fate acquisition in dermal macrophages. Our study identifies an essential role for the metabolite lactate in regulating macrophage responses to inflammation, which may be effectively targeted to treat inflammatory skin disorders such as psoriasis. Synopsis: Inflammation alters skin tissue metabolism, however, the consequences for immune cell effector function remain unclear. Here, in vivo work in mice uncovers a ROS/HIF-1α-induced metabolic crosstalk between epidermal cells and macrophages during sterile inflammation, which aggravates disease progression. Induced skin inflammation shifts metabolic preferences to glycolysis and the TCA cycle in the epidermis and in macrophages, respectively. Inflammation-induced metabolic compartmentalisation is bridged by lactate secreted from the epidermis. Inhibition of lactate transport leads to reduced macrophage-mediated ECM degradation and in turn, inflammation. Inhibition of lactate transfer attenuates psoriasis symptoms in a imiquimod-induced mouse model. Lactate produced via glycolysis in epidermal cells activates NF-κB signaling and M2-like pro-remodeling phenotypes in dermal macrophages. [ABSTRACT FROM AUTHOR]

Increasing numbers of studies have shown that tumor cells prefer fermentative glycolysis over oxidative phosphorylation to provide a vast amount of energy for fast proliferation even under oxygen‐sufficient conditions. This metabolic alteration not only favors tumor cell progression and metastasis but also increases lactate accumulation in solid tumors. In addition to serving as a byproduct of glycolytic tumor cells, lactate also plays a central role in the construction of acidic and immunosuppressive tumor microenvironment, resulting in therapeutic tolerance. Recently, targeted drug delivery and inherent therapeutic properties of nanomaterials have attracted great attention, and research on modulating lactate metabolism based on nanomaterials to enhance antitumor therapy has exploded. In this review, the advanced tumor therapy strategies based on nanomaterials that interfere with lactate metabolism are discussed, including inhibiting lactate anabolism, promoting lactate catabolism, and disrupting the "lactate shuttle". Furthermore, recent advances in combining lactate metabolism modulation with other therapies, including chemotherapy, immunotherapy, photothermal therapy, and reactive oxygen species‐related therapies, etc., which have achieved cooperatively enhanced therapeutic outcomes, are summarized. Finally, foreseeable challenges and prospective developments are also reviewed for the future development of this field. [ABSTRACT FROM AUTHOR]

Lactate is not only an endpoint of glycolysis but is gradually being discovered to play the role of a universal metabolic fuel for energy via the ‘lactate shuttle’ moving between cells and transmitting signals. The glycolytic-dependent metabolism found in tumours and fast-growing cells has made lactate a pivotal player in energy metabolism reprogramming, which enables cells to obtain abundant energy in a short time. Moreover, lactate can provide favourable conditions for tumorigenesis by shaping the acidic tumour microenvironment, recruiting immune cells, etc. and the recently discovered lactate-induced lactylation moves even further on pro-tumorigenesis mechanisms of lactate production, circulation and utilization. As with other epigenetic modifications, lactylation can modify histone proteins to alter the spatial configuration of chromatin, affect DNA accessibility and regulate the expression of corresponding genes. What's more, the degree of lactylation is inseparable from the spatialized lactate concentration, which builds a bridge between epigenetics and metabolic reprogramming. Here, we review the important role of lactate in energy reprogramming, summarize the latest finding of lactylation in tumorigenesis and try to explore therapeutic strategies in oncotherapy that can kill two birds with one stone. [ABSTRACT FROM AUTHOR]

MCT1 is a critical protein found in monocarboxylate transporters that plays a significant role in regulating the lactate shuttle. However, the post‐transcriptional modifications that regulate MCT1 are not clearly identified. In this study, it is reported that SETDB1 interacts with MCT1, leading to its stabilization. These findings reveal a novel post‐translational modification of MCT1, in which SETDB1 methylation occurs at K473 in vitro and in vivo. This methylation inhibits the interaction between MCT1 and Tollip, which blocks Tollip‐mediated autophagic degradation of MCT1. Furthermore, MCT1 K473 tri‐methylation promotes tumor glycolysis and M2‐like polarization of tumor‐associated macrophages in colorectal cancer (CRC), which enhances the lactate shuttle. In clinical studies, MCT1 K473 tri‐methylation is found to be upregulated and positively correlated with tumor progression and overall survival in CRC. This discovery suggests that SETDB1‐mediated tri‐methylation at K473 is a vital regulatory mechanism for lactate shuttle and tumor progression. Additionally, MCT1 K473 methylation may be a potential prognostic biomarker and promising therapeutic target for CRC. [ABSTRACT FROM AUTHOR]

Background: Cervical cancer is one of the most common gynecological cancers. Accumulated evidence shows that long non‐coding RNAs (lncRNAs) play essential roles in cervical cancer occurrence and progression, but their specific functions and mechanisms remain to be further explored. Methods: The RT‐qPCR assay was used to detect the expression of NEAT1 in cervical cancer tissues and cell lines. CCK‐8, colony formation, flow cytometry, western blotting, and Transwell assays were used to evaluate the impact of NEAT1 on the malignant behavior of cervical cancer cells. Glucose consumption, lactate production, ATP levels, ROS levels, MMP levels, and the mRNA expressions of glycolysis‐related genes and tricarboxylic acid cycle‐related genes were detected to analyze the effect of NEAT1 on metabolism reprograming in cervical cancer cells. The expressions of PDK1, β‐catenin and downstream molecules of the WNT/β‐catenin signaling pathway in cervical cancer cells and tissues were detected by western blotting, RT‐qPCR, immunofluorescence and immunohistochemistry assays. Results: This study investigated the role and possible molecular mechanism of lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) in cervical cancer. Our results showed that NEAT1 was highly expressed in cervical cancer tissues and cell lines. Downregulation of NEAT1 inhibited the proliferation, migration, invasion and glycolysis of cervical cancer cells, while overexpression of NEAT1 led to the opposite effects. Mechanistically, NEAT1 upregulated pyruvate dehydrogenase kinase (PDK1) through the WNT/β‐catenin signaling pathway, which enhanced glycolysis and then facilitated cervical cancer metastasis. Furthermore, NEAT1 maintained the protein stability of β‐catenin but did not affect its mRNA level. We also excluded the direct binding of NEAT1 to the β‐catenin protein via RNA pull‐down assay. The suppressive impact of NEAT1 knockdown on cell proliferation, invasion, and migration was rescued by β‐catenin overexpression. The WNT inhibitor iCRT3 attenuated the carcinogenic effect induced by NEAT1 overexpression. Conclusion: In summary, these findings indicated that NEAT1 may contribute to the progression of cervical cancer by activating the WNT/β‐catenin/PDK1 signaling axis. [ABSTRACT FROM AUTHOR]

Background: Breast cancer (BC) is a common malignancy which threatens the health of women. Circular RNAs (circRNAs) are critical factors in multiple cancers, including BC. The aim of this experiment was to investigate the molecular mechanisms of circRNA Septin 9 (circSEPT9) in the progression of BC. Methods: CircSEPT9, microRNA-625-5p (miR-625-5p) and polypyrimidine tractbinding protein 3 (PTBP3) levels were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was performed to detect the protein levels of PTBP3, E-cadherin and vimentin. Cell counting kit-8 assay (CCK8) and thymidine analog 5-ethynyl-20-deoxyuridine (EDU) was utilized for proliferation examination. Flow cytometry was conducted to measure apoptosis. Transwell assay and wound healing assay to investigate the migration of BC cells. Glucose uptake and lactate production were determined by specific kits. Additionally, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were utilized to verify the interaction. A murine xenograft model was established to investigate the function of circSEPT9 in BC in vivo. Results: Overexpression of circSEPT9 was found in BC tissues and cells. Silencing circSEPT9 impeded BC cell proliferation, migration, epithelial-mesenchymal transition (EMT) and glycolytic metabolism but facilitated cell apoptosis in vitro. Meanwhile, circSEPT9 knockdown constrained tumor growth in vivo. MiR-625-5p was targeted by circSEPT9. The influence of silencing circSEPT9 on BC cell function was regained by miR-625-5p inhibitor. Furthermore, miR-625-5p regulated BC cell malignant phenotypes via downregulating PTBP3. Conclusion: circSEPT9 contributed to the malignant progression of BC by upregulating PTBP3 via sponging miR-625-5p. [ABSTRACT FROM AUTHOR]

Colon cancer is a common cancer with high mortality globally. The role of chondroitin polymerizing factor (CHPF) has been elucidated in various cancers. However, its role and mechanism remain unknown in colon cancer. CHPF expression was examined by GEPIA database, reverse transcription‐quantitative polymerase chain reaction and western blot. The relationship between CHPF expression and the clinicopathologic characteristics as well as miR‐214‐3p level was determined in colon cancer patients. The role and mechanism of CHPF in the growth, ferroptosis, and glycolysis of colon cancer cells were evaluated by cell counting kit‐8, biochemical detections, luciferase, and western blot experiments. Additionally, the role of CHPF was explored in xenografted mice. CHPF expression was increased and was related to advanced TNM stage, poor differentiation and shorter overall survival in patients with colon cancer. Knockdown of CHPF inhibited colon cancer cell growth, and downregulated the expression of proteins involving in ferroptosis and glycolysis both in vitro and in vivo. Besides, CHPF silencing increased the levels of ferrous iron and ROS, but decreased glucose uptake, lactate product, and ATP level in vitro. Mechanically, miR‐214‐3p directly targeted CHPF and negatively regulated its expression. Upregulation of miR‐214‐3p reduced cell viability, glucose uptake, lactate product, and ATP level, but increased the levels of ferrous iron and ROS, which were reversed by the overexpression of CHPF. Upregulation of CHPF predicted poor prognosis, and miR‐214‐3p/CHPF axis inhibited growth, downregulated the levels of glycolysis‐related indexes, and promoted ferroptosis in colon cancer cells. [ABSTRACT FROM AUTHOR]

Metastasis is an important contributor to increased mortality rates in non‐small cell lung cancer (NSCLC). The TGF‐β signalling pathway plays a crucial role in facilitating tumour metastasis through epithelial‐mesenchymal transition (EMT). Glycolysis, a key metabolic process, is strongly correlated with NSCLC metastasis. Pirfenidone (PFD) has been shown to safely and effectively inhibit TGF‐β1 in patients with lung diseases. Furthermore, TGF‐β1 and glycolysis demonstrate an interdependent relationship within the tumour microenvironment. Our previous study demonstrated that PFD effectively inhibited glycolysis in NSCLC cells, prompting further investigation into its potential antitumour effects in this context. Therefore, the present study aims to investigate the potential antitumour effect of PFD in NSCLC and explore the relationship among TGF‐β1, glycolysis and EMT through further experimentation. The antitumour effects of PFD were evaluated using five different NSCLC cell lines and a xenograft tumour model. Notably, PFD demonstrated a significant antitumour effect specifically in highly glycolytic H1299 cells. To elucidate the underlying mechanism, we compared the efficacy of PFD after pretreatment with either TGF‐β1 or a TGF‐β receptor inhibitor (LY2109761). The energy metabolomics analysis of tumour tissue demonstrated that PFD, a chemosensitizing agent, reduced lactate and ATP production, thereby inhibiting glycolysis and exerting synergistic antineoplastic effects. Additionally, PFD combined with cisplatin targeted TGF‐β1 to inhibit glycolysis during EMT and enhanced the chemosensitization of A549 and H1299 cells. The magnitude of the anticancer effect exhibited by PFD was intricately linked to its metabolic properties. [ABSTRACT FROM AUTHOR]

An effective systemic mechanism regulates tumor development and progression; thus, a rational design in a one‐stone‐two‐birds strategy is meant for cancer treatment. Herein, a hollow Fe3O4 catalytic nanozyme carrier co‐loading lactate oxidase (LOD) and a clinically‐used hypotensor syrosingopine (Syr) are developed and delivered for synergetic cancer treatment by augmented self‐replenishing nanocatalytic reaction, integrated starvation therapy, and reactivating anti‐tumor immune microenvironment. The synergetic bio‐effects of this nanoplatform stemmed from the effective inhibition of lactate efflux through blocking the monocarboxylate transporters MCT1/MCT4 functions by the loaded Syr as a trigger. Sustainable production of hydrogen peroxide by catalyzation of the increasingly residual intracellular lactic acid by the co‐delivered LOD and intracellular acidification enabled the augmented self‐replenishing nanocatalytic reaction. Large amounts of produced reactive oxygen species (ROS) damaged mitochondria to inhibit oxidative phosphorylation as the substituted energy supply upon the hampered glycolysis pathway of tumor cells. Meanwhile, remodeling anti‐tumor immune microenvironment is implemented by pH gradient reversal, promoting the release of proinflammatory cytokines, restored effector T and NK cells, increased M1‐polarize tumor‐associated macrophages, and restriction of regulatory T cells. Thus, the biocompatible nanozyme platform achieved the synergy of chemodynamic/immuno/starvation therapies. This proof‐of‐concept study represents a promising candidate nanoplatform for synergetic cancer treatment. [ABSTRACT FROM AUTHOR]

Imatinib is the frontline treatment option in treating chronic myelogenous leukemia (CML). Hitherto, some patients relapse following treatment. Biochemical analysis of a panel of clonally derived imatinib‐resistant cells revealed enhanced glucose uptake and ATP production, suggesting increased rates of glycolysis. Interestingly, increased lactate export was also observed in imatinib‐resistant cell lines. Here, we show that metformin inhibits the growth of imatinib‐resistant cell lines as well as peripheral blood mononuclear cells isolated from patients who relapsed following imatinib treatment. Metformin exerted these antiproliferative effects by inhibiting MCT1 and MCT4, leading to the inhibition of lactate export. Furthermore, glucose uptake and ATP production were also inhibited following metformin treatment due to the inhibition of GLUT1 and HK‐II in an AMPK‐dependent manner. Our results also confirmed that metformin‐mediated inhibition of lactate export and glucose uptake occurs through the regulation of mTORC1 and HIF‐1α. These results delineate the molecular mechanisms underlying metabolic reprogramming leading to secondary imatinib resistance and the potential of metformin as a therapeutic option in CML. [ABSTRACT FROM AUTHOR]

Background: Cancer stem cells are pivotal in cancer progression and therapy, including lung adenocarcinoma (LUAD). High NCAPG level is implicated in malignant tumorigenesis, but investigations on NCAPG and LUAD stem cells are warranted. Hence, projecting the impact of NCAPG on cell stemness and the targeted therapy for LUAD is of the essence. Methods: Bioinformatics analyzed NCAPG expression in LUAD tissues. qRT‐PCR assayed NCAPG expression in LUAD cells. CCK‐8 assessed cell viability and cell sphere‐forming assay measured sphere‐forming ability. Western blot assessed expression of stem cell‐related markers (CD133, CD44, Oct‐4) and specific genes (HK2, PKM2, LDHA) related to glycolysis metabolism pathway. Cellular glycolytic capacity was assayed by glycolytic metabolites pyruvic acid, lactate, citrate, and malate assay kits, and extracellular acidification rate and oxygen consumption rate analyzers. Results: NCAPG was upregulated in LUAD and enriched in the aerobic glycolysis pathway, and its expression was positively correlated with that of glycolytic marker genes. Cell function assays revealed that NCAPG stimulated proliferation, stemness, and glycolytic activity of LUAD cells. Rescue experiments unveiled that 2‐DG (glycolysis inhibitor) was able to reverse the stimulative impact of NCAPG overexpression on proliferation, stemness, and glycolytic activity of LUAD cells. Conclusion: NCAPG stimulated LUAD cell stemness through activation of glycolysis pathway. NCAPG may be possible biomarker for diagnosis and target for treatment of LUAD. [ABSTRACT FROM AUTHOR]

Introduction: This study endeavored to investigate the role of DOCK8 in modulating the immune function triggered by sepsis. Methods: Expression of DOCK8 in the whole blood of sepsis patients and its enrichment pathways were assayed by bioinformatics. Pearson analysis was used to predict the relationship between glycolytic signaling pathway and its relevance to neutrophil function in sepsis. A sepsis mouse model was then built by performing cecal ligation and puncture treatment on male mice. Neutrophils were isolated, and their purity was tested by flow cytometry. Neutrophils were then stimulated by lipopolysaccharide to build a sepsis cell model. Next, quantitative reverse transcription polymerase chain reaction and CCK‐8 were applied to test the expression of DOCK8 and cell viability, western blot to assay the expression of HK‐2, PKM2, and LDHA proteins, ELISA to measure the concentrations of TNF‐α, IL‐1β, and IL‐6, Transwell to detect the chemotaxis of neutrophils and flow cytometry to detect the phagocytic activity of neutrophils. Finally, in different treatment groups, we used Seahorse XF 96 to analyze the extracellular acidification rate (ECAR) of sepsis cells and used enzyme‐linked immunosorbent assay to detect the contents of pyruvic acid, lactic acid, and ATP in sepsis cells. Results: DOCK8 was downregulated in sepsis blood and activated neutrophils. Aerobic glycolysis was positively correlated with sepsis. Activated neutrophils promoted the expression of inflammatory factors TNF‐α, IL‐1β, and IL‐6. Low expression of DOCK8 facilitated the proliferation, chemotaxis, and phagocytic activity of sepsis cells and promoted the expression of inflammatory factors. Bioinformatics analysis revealed that DOCK8 was enriched in the glycolytic signaling pathway. Low expression of DOCK8 induced ECAR, promoted the protein expression of HK‐2, PKM2 and LDHA, and favored the increase of pyruvate, lactate, and ATP contents. While 2‐DG treatment could restore these effects. Conclusion: DOCK8 may inhibit sepsis‐induced neutrophil immune function by regulating aerobic glycolysis and causing excessive inflammation, which helps to explore potential therapeutic targets. [ABSTRACT FROM AUTHOR]

Endometriosis is a gynaecological condition characterized by the growth of endometrium‐like tissues within and outside of the pelvic cavity. Recent studies have demonstrated that aberrant infiltration of M2 macrophages is mainly responsible for the establishment of endometriotic lesions. A growing body of evidence shows that glycolysis and lactate accumulation have great impact on the regulation of immunomicroenvironment. However, the communication signal between glycolysis and macrophages is poorly defined in endometriosis. Hereby, we investigate the correlation between glycolysis and M2 macrophage infiltration in endometriosis. Next, we confirm that lactate is pivotal factor that drives macrophage M2‐polarization to promote endometriotic stromal cells invasion in vitro and in vivo. In addition, we also identify that the activation of Mettl3 and its target gene Trib1 promote M2 macrophage polarization. Moreover, we also demonstrate that Trib1 induce M2 macrophage polarization via the activation of ERK/STAT3 signalling pathway. Finally, by injecting 2‐DG into endometriosis mice model, we show that the restrain of glycolysis significantly reduces the progression of endometriosis, which provides evidence for lactate as a potential therapeutic strategy for the prevention and treatment of endometriosis. [ABSTRACT FROM AUTHOR]

Background: Lung cancer is the most common malignancy in the world and a growing number of researches have focused on its metabolic characteristics. Studies have shown that the long non‐coding RNA (lncRNA) HOXA11‐AS is aberrantly expressed in many tumors. However, the role of HOXA11‐AS in lung adenocarcinoma (LUAD) glycolysis and other energy metabolism pathways has not been characterized. Method: The mRNA levels of HOXA11‐AS, microRNA‐148b‐3p (miR‐148b‐3p), and pyruvate kinase M2 (PKM2) were detected using qRT‐PCR. The expression levels of proteins were measured using immunohistochemistry and western blot. The CCK‐8, EdU, and colony formation assays were used to assess proliferation. Glycolytic changes were assessed by measuring lactate production, ATP production, and 18F‐FDG uptake. Bioinformatics analysis and dual‐luciferase reporter assays were used to characterize the relationship between HOXA11‐AS, miR‐148b‐3p, and PKM2. Proliferation and glycolytic changes were analyzed in xenograft tumor experiments using Micro‐PET imaging after downregulation of HOXA11‐AS in vivo. Results: The expression of HOXA11‐AS was markedly increased in LUAD, and was strongly associated with a poor prognosis. In addition, HOXA11‐AS promoted proliferation and glycolysis in LUAD, and miR‐148b‐3p inhibited proliferation and glycolysis in LUAD. Mechanistically, HOXA11‐AS positively regulated PKM2 expression by binding to miR‐148b‐3p, thereby promoting LUAD proliferation and glycolysis. In addition, HOXA11‐AS inhibited LUAD xenograft growth and glycolysis via upregulation of miR‐148b‐3p expression and downregulation of PKM2 expression in vivo. Conclusions: These results showed that HOXA11‐AS enhanced LUAD proliferation and glycolysis via the miR‐148b‐3p/PKM2 axis. The findings in this paper expanded our understanding of the molecular mechanisms of LUAD tumorigenesis and glycolysis and showed that HOXA11‐AS could be useful as a diagnostic and prognostic marker for LUAD. 18F‐FDG PET/CT can be used to visually evaluate the therapeutic effect of targeting HOXA11‐AS. [ABSTRACT FROM AUTHOR]

Background: Breast cancer is widespread in females. The role of circular RNA (circRNA) in breast cancer has aroused much attention. However, the function of several circRNAs remain unclear. The aim of our study was to determine the role of circ_0001955 in breast cancer. Methods: Quantitative real‐time PCR (qPCR) and western blot was employed for expression analysis of circ_0001955, miR‐1299 and glucose transporter 1 (GLUT1). Cell functions including proliferation, apoptosis, migration, invasion and angiogenesis, were assessed using EdU, flow cytometry, transwell and tube formation assays. Glycolysis metabolism was assessed according to glucose consumption, lactate production and ATP content. Dual‐luciferase reporter assay and RIP assay were utilized to validate the binding between miR‐1299 and circ_0001955 or GLUT1. The effects of circ_0001955 in vivo were observed by animal study. Results: Upregulation of circ_0001955 was detected in breast cancer. Knockdown of circ_0001955 inhibited breast cancer cell proliferation, migration, invasion, angiogenesis and glycolysis. MiR‐1299 was a target of circ_0001955, and its repression reversed the effects of circ_0001955 knockdown. Moreover, circ_0001955 targeted miR‐1299 to positively regulate GLUT1 expression. GLUT1 overexpression reversed the effects of miR‐1299 enrichment. GLUT1 knockdown was verified to block tumor growth in vivo. Conclusions: Circ_0001955 was found to promote breast cancer malignant development via targeting of the miR‐1299/GLUT1 pathway, which contributes to our understanding of the pathogenesis of breast cancer. [ABSTRACT FROM AUTHOR]

Background: Activation of ALK leads to a high level of aerobic glycolysis related to crizotinib insensitivity in anaplastic lymphoma kinase‐positive non‐small cell lung cancer (ALK+ NSCLC). The strategy and mechanism of glycolysis inhibition in sensitizing ALK+ NSCLC cells to crizotinib requires further investigation. Methods: The levels of glycolysis in H3122 and H2228 cells were evaluated through detection of glucose consumption and lactate production. MTT assay was used to explore the effects of glycolytic inhibitors on crizotinib sensitivity, and the potential mechanism of action were detected by colony formation, Ki67 incorporation assay, transwell assay, small interfering RNA technology and western blot analysis. Results: ALK+ NSCLC cells exhibited significantly higher levels of glycolysis compared to ALK− NSCLC cells. Long‐term exposure to crizotinib could decrease the sensitivity of ALK+ NSCLC cells to crizotinib via increasing the levels of glycolysis related to hexokinases II (HK2). Crizotinib in combination with glycolysis inhibitor 2‐deoxy‐D‐glucose (2DG) synergistically inhibited proliferation, glycolysis, colony formation and invasion ability of ALK+ NSCLC cells. 2DG sensitization crizotinib might be associated with the inhibition of HK2‐mediated glycolysis and P‐ALK/AKT/mTOR signaling pathway in H3122 and H2228 cells. Conclusions: These results indicate that HK2‐mediated glycolysis plays a crucial role in the increased tolerance of ALK+ NSCLC cells to crizotinib. 2DG may sensitize ALK+ NSCLC to crizotinib via suppression of HK2‐mediated glycolysis and the AKT/mTOR signaling pathway. [ABSTRACT FROM AUTHOR]

Objective: In rheumatoid arthritis (RA), elevated serum interleukin‐34 (IL‐34) levels are linked with increased disease severity. IL‐34 binds to 2 receptors, macrophage colony‐stimulating factor receptor (M‐CSFR) and syndecan 1, which are coexpressed in RA macrophages. Expression of both IL‐34 and syndecan 1 is strikingly elevated in the RA synovium, yet their mechanisms of action remain undefined. This study was undertaken to investigate the mechanism of action of IL‐34 in RA. Methods: To characterize the significance of IL‐34 in immunometabolism, its mechanism of action was elucidated in joint macrophages, fibroblasts, and T effector cells using RA and preclinical models. Results: Intriguingly, syndecan 1 activated IL‐34–induced M‐CSFR phosphorylation and reprogrammed RA naive cells into distinctive CD14+CD86+GLUT1+ M34 macrophages that expressed elevated levels of IL‐1β, CXCL8, and CCL2. In murine M34 macrophages, the inflammatory phenotype was accompanied by potentiated glycolytic activity, exhibited by transcriptional up‐regulation of GLUT1, c‐Myc, and hypoxia‐inducible factor 1α (HIF‐1α) and amplified pyruvate and l‐lactate secretion. Local expression of IL‐34 provoked arthritis by expanding the glycolytic F4/80‐positive, inducible nitric oxide synthase (iNOS)–positive macrophage population, which in turn attracted fibroblasts and polarized Th1/Th17 cells. The cross‐talk between murine M34 macrophages and Th1/Th17 cells broadened the inflammatory and metabolic phenotypes, resulting in the expansion of IL‐34 pathogenicity. Consequently, IL‐34–instigated joint inflammation was alleviated in RAG−/− mice compared to wild‐type mice. Syndecan 1 deficiency attenuated IL‐34–induced arthritis by interfering with joint glycolytic M34 macrophage and osteoclast remodeling. Similarly, inhibition of glycolysis by 2‐deoxy‐d‐glucose reversed the joint swelling and metabolic rewiring triggered by IL‐34 via HIF‐1α and c‐Myc induction. Conclusion: IL‐34 is a novel endogenous factor that remodels hypermetabolic M34 macrophages and facilitates their cross‐regulation with T effector cells to advance inflammatory bone destruction in RA. [ABSTRACT FROM AUTHOR]

Gastric cancer is the fifth most common malignancy and the third most deadly tumor in the world. Zinc finger protein 479 (ZNF479) has been demonstrated to play crucial roles in hepatocellular carcinoma. However, the function of ZNF479 in gastric cancer remains to be clarified. The current study aimed to investigate the role of ZNF479 in gastric cancer progression and elucidate the potential molecular mechanism. In this study, Cell Count Kit‐8 and colony formation assays demonstrated that knockdown of ZNF479 inhibited cell proliferation in AGS and SGC‐7901 cells. Of note, knockdown of ZNF479 hinders tumor growth of xenograft tumor mice. What is more, knockdown of ZNF479 inhibited glucose uptake, lactate production, adenosine triphosphate level, and extracellular acidification ratio; increased oxygen consumption ratio in gastric cancer cells; and decreased the expression of glycolytic proteins both in vitro and in vivo. Furthermore, analysis mechanism suggests that ZNF479 participated in the regulation of gastric cancer progression through affecting the β‐catenin/c‐Myc signaling pathway. Collectively, ZNF479 plays a role as an oncogene through modulating β‐catenin/c‐Myc signaling pathway in the development of gastric cancer, which provides a new research target for future studies. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to present calculations of fractional H+ exchange (~H+e) from the chemical reactions of non‐mitochondrial energy catabolism. Data of muscle pH and metabolite accumulation were based on published research for intense exercise to contractile failure within ~3 min, from which capacities and time profiles were modeled. Data were obtained from prior research for multiple competitive cation dissociation constants of metabolites and the chemical reactions of non‐mitochondrial energy catabolism, and pH dependent calculations of ~H+e from specific chemical reactions. Data revealed that the 3 min of intense exercise incurred a total ATP turnover of 142.5 mmol L−1, with a total intramuscular ~H+ exchange (‐'ve = release) of −187.9 mmol L−1. Total ~H+ metabolic consumption was 130.6 mmol L−1, revealing a net total ~H+e (~H+te) of −57.3 mmol L−1. Lactate production had a ~H+te of 44.2 mmol L−1 (for a peak accumulation = 45 mmol L−1). The net ~H+te for the sum of the CK, AK, and AMPD reactions was 36.33 mmol L−1. The ~H+te from ATP turnover equaled −47.5 mmol L−1. The total ~H+ release to lactate ratio was 4.3 (187.9/44). Muscle ~H+ release during intense exercise is up to ~4‐fold larger than previously assumed based on the lactic acid construct. [ABSTRACT FROM AUTHOR]

The metabolism of Chinese hamster ovary (CHO) cell lines is typically characterized by high rates of aerobic glycolysis with increased lactate formation, known as the "Warburg" effect. Although this metabolic state can switch to lactate consumption, the involved regulations of the central metabolism have only been partially studied so far. An important reaction transferring the lactate precursor, pyruvate, into the tricarboxylic acid cycle is the decarboxylation reaction catalyzed by the pyruvate dehydrogenase enzyme complex (PDC). Among other mechanisms, PDC is mainly regulated by phosphorylation–dephosphorylation at the three sites Ser232, Ser293, and Ser300. In this work, the PDC phosphorylation in antibody‐producing CHO DP‐12 cell culture is investigated during the lactate switch. Batch cultivations were carried out with frequent sampling (every 6 h) during the transition from lactate formation to lactate uptake, and the PDC phosphorylation levels were quantified using a novel indirect flow cytometry protocol. Contrary to the expected activation of PDC (i.e., reduced PDC phosphorylation) during lactate consumption, Ser293 and Ser300 phosphorylation levels were 33% higher compared to the phase of glucose excess. At the same time, the relative phosphorylation level of Ser232 increased steadily throughout the cultivation (66% increase overall). The intracellular pyruvate was found to accumulate only during the period of high lactate production, while acetyl‐CoA showed nearly no accumulation. These results indicate a deactivation of PDC and reduced oxidative metabolism during lactate switch even though the cells undergo a metabolic transition to lactate‐based cell growth and metabolism. Overall, this study provides a unique view on the regulation of PDC during the lactate switch, which contributes to an improved understanding of PDC and its interaction with the bioprocess. [ABSTRACT FROM AUTHOR]

Mitochondrial structures were probably observed microscopically in the 1840s, but the idea of oxidative phosphorylation (OXPHOS) within mitochondria did not appear until the 1930s. The foundation for research into energetics arose from Meyerhof's experiments on oxidation of lactate in isolated muscles recovering from electrical contractions in an O2 atmosphere. Today, we know that mitochondria are actually reticula and that the energy released from electron pairs being passed along the electron transport chain from NADH to O2 generates a membrane potential and pH gradient of protons that can enter the molecular machine of ATP synthase to resynthesize ATP. Lactate stands at the crossroads of glycolytic and oxidative energy metabolism. Based on reported research and our own modelling in silico, we contend that lactate is not directly oxidized in the mitochondrial matrix. Instead, the interim glycolytic products (pyruvate and NADH) are held in cytosolic equilibrium with the products of the lactate dehydrogenase (LDH) reaction and the intermediates of the malate‐aspartate and glycerol 3‐phosphate shuttles. This equilibrium supplies the glycolytic products to the mitochondrial matrix for OXPHOS. LDH in the mitochondrial matrix is not compatible with the cytoplasmic/matrix redox gradient; its presence would drain matrix reducing power and substantially dissipate the proton motive force. OXPHOS requires O2 as the final electron acceptor, but O2 supply is sufficient in most situations, including exercise and often acute illness. Recent studies suggest that atmospheric normoxia may constitute a cellular hyperoxia in mitochondrial disease. As research proceeds appropriate oxygenation levels should be carefully considered. [ABSTRACT FROM AUTHOR]

Objective: CD8+ T cells contribute to rheumatoid arthritis (RA) by releasing proinflammatory and cytolytic mediators, even in a challenging hypoxic and nutrient‐poor microenvironment such as the synovial membrane. This study was undertaken to explore the mechanisms through which CD8+ T cells meet their metabolic demands in the blood and synovial membrane of patients with RA. Methods: Purified blood CD8+ T cells from patients with RA, patients with psoriatic arthritis (PsA), and patients with spondyloarthritis (SpA), as well as healthy control subjects, and CD8+ T cells from RA synovial membrane were stimulated in medium containing 13C‐labeled metabolic substrates in the presence or absence of metabolic inhibitors, under conditions of normoxia or hypoxia. The production of metabolic intermediates was quantified by 1H‐nuclear magnetic resonance. The expression of metabolic enzymes, transcription factors, and immune effector molecules was assessed at both the messenger RNA (mRNA) and protein levels. CD8+ T cell functional studies were performed. Results: RA blood CD8+ T cells met their metabolic demands through aerobic glycolysis, production of uniformly 13C‐enriched lactate in the RA blood (2.6 to 3.7–fold higher than in patients with SpA, patients with PsA, and healthy controls; P < 0.01), and induction of glutaminolysis. Overexpression of Warburg effect–linked enzymes in all RA CD8+ T cell subsets maintained this metabolic profile, conferring to the cells the capacity to proliferate under hypoxia and low‐glucose conditions. In all RA CD8+ T cell subsets, lactate dehydrogenase A (LDHA) was overexpressed at the mRNA level (P < 0.03 versus controls; n = 6 per group) and protein level (P < 0.05 versus controls; n = 17 RA patients, n = 9 controls). In RA blood, inhibition of LDHA with FX11 led to reductions in lipogenesis, migration and proliferation of CD8+ T cells, and CD8+ T cell effector functions, while production of reactive oxygen species was increased by 1.5‐fold (P < 0.03 versus controls). Following inhibition of LDHA with FX11, RA CD8+ T cells lost their capacity to induce healthy B cells to develop a proinflammatory phenotype. Similar metabolic alterations were observed in RA CD8+ T cells from the synovial membrane. Conclusion: Remodeling glucose and glutamine metabolism in RA CD8+ T cells by targeting LDHA activity can reduce the deleterious inflammatory and cytolytic contributions of these cells to the development of autoimmunity. [ABSTRACT FROM AUTHOR]

Abstract: We examined the effects of lactate on the enzymatic activity of hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK) in various mouse tissues. Our results showed that lactate inhibited PFK activity in all the analyzed tissues. This inhibitory effect was observed in skeletal muscle even in the presence of insulin. Lactate directly inhibited the phosphorylation of PFK tyrosine residues in skeletal muscle, an important mechanism of the enzyme activation. Moreover, lactate indirectly inhibited HK activity, which resulted from its cellular redistribution, here attributed to alterations of HK structure. PK activity was not affected by lactate. The activity of HK and PFK is directly related to glucose metabolism. Thus, it is conceivable that lactate exposure can induce inhibition of glucose consumption in tissues. [ABSTRACT FROM AUTHOR]

Elevated glycolysis remains a universal and primary character of cancer metabolism, which deeply depends on dysregulated metabolic enzymes. Lactate dehydrogenase A (LDHA) facilitates glycolytic process by converting pyruvate to lactate. Numerous researches demonstrate LDHA has an aberrantly high expression in multiple cancers, which is associated with malignant progression. In this review, we summarized LDHA function in cancer research. First, we gave an introduction of structure, location, and basic function of LDHA. Following, we discussed the transcription and activation mode of LDHA. Further, we focused on the function of LDHA in cancer bio‐characteristics. Later, we discussed the clinical practice of LDHA in cancer prevention and treatment. What we discussed gives a precise insight into LDHA especially in cancer research, which will contribute to exploring cancer pathogenesis and its handling measures. LDHA contributes to diverse bio‐characteristics of tumors via numerous mechanisms. LDHA has been used as a tumor biomarker for clinical diagnosis and treatment and is considered as a potential anticancer target. [ABSTRACT FROM AUTHOR]

For much of the 20th century, lactate was largely considered a dead-end waste product of glycolysis due to hypoxia, the primary cause of the O2 debt following exercise, a major cause of muscle fatigue, and a key factor in acidosis-induced tissue damage. Since the 1970s, a 'lactate revolution' has occurred. At present, we are in the midst of a lactate shuttle era; the lactate paradigm has shifted. It now appears that increased lactate production and concentration as a result of anoxia or dysoxia are often the exception rather than the rule. Lactic acidosis is being re-evaluated as a factor in muscle fatigue. Lactate is an important intermediate in the process of wound repair and regeneration. The origin of elevated [lactate] in injury and sepsis is being re-investigated. There is essentially unanimous experimental support for a cell-to-cell lactate shuttle, along with mounting evidence for astrocyte-neuron, lactate-alanine, peroxisomal and spermatogenic lactate shuttles. The bulk of the evidence suggests that lactate is an important intermediary in numerous metabolic processes, a particularly mobile fuel for aerobic metabolism, and perhaps a mediator of redox state among various compartments both within and between cells. Lactate can no longer be considered the usual suspect for metabolic 'crimes', but is instead a central player in cellular, regional and whole body metabolism. Overall, the cell-to-cell lactate shuttle has expanded far beyond its initial conception as an explanation for lactate metabolism during muscle contractions and exercise to now subsume all of the other shuttles as a grand description of the role(s) of lactate in numerous metabolic processes and pathways. [ABSTRACT FROM AUTHOR]

The authors comment on research on astrocyte-to-neuron lactate shutte in the brain. The astrocyte-to-neuron lactate shuttle hypothesis was published by L. Pellerin and P.J. Magistretti in 1994. The authors argue that there is net lactate transfer from astrocytes to neurons which is important for brain function.

Abstract: Accumulating evidences showed metformin and berberine, well‐known glucose‐lowering agents, were able to inhibit mitochondrial electron transport chain at complex I. In this study, we aimed to explore the antihyperglycaemic effect of complex I inhibition. Rotenone, amobarbital and gene silence of NDUFA13 were used to inhibit complex I. Intraperitoneal glucose tolerance test and insulin tolerance test were performed in db/db mice. Lactate release and glucose consumption were measured to investigate glucose metabolism in HepG2 hepatocytes and C2C12 myotubes. Glucose output was measured in primary hepatocytes. Compound C and adenoviruses expressing dominant negative AMP‐activated protein kinase (AMPK) α1/2 were exploited to inactivate AMPK pathway. Cellular NAD+/NADH ratio was assayed to evaluate energy transforming and redox state. Rotenone ameliorated hyperglycaemia and insulin resistance in db/db mice. It induced glucose consumption and glycolysis and reduced hepatic glucose output. Rotenone also activated AMPK. Furthermore, it remained effective with AMPK inactivation. The enhanced glycolysis and repressed gluconeogenesis correlated with a reduction in cellular NAD+/NADH ratio, which resulted from complex I suppression. Amobarbital, another representative complex I inhibitor, stimulated glucose consumption and decreased hepatic glucose output in vitro, too. Similar changes were observed while expression of NDUFA13, a subunit of complex I, was knocked down with gene silencing. These findings reveal mitochondrial complex I emerges as a key drug target for diabetes treatment. Inhibition of complex I improves glucose homoeostasis via non‐AMPK pathway, which may relate to the suppression of the cellular NAD+/NADH ratio. [ABSTRACT FROM AUTHOR]

Interactions between α-adrenergic-induced lactate production, respiration and K+ uptake of perfused rat livers were investigated. Inhibition of mitochondrial electron transport by cyanide had no effect on K+ uptake. decreased phenylephrine-induced lactate production by 60% and suppressed extra O2 consumption by more than 90%. Ouabain did not affect α-adrenergic-induced respiration but inhibited K+ uptake and extra lactate production. Effects of ouabain and K+-free medium on lactate production were additive and independent of cyanide, indicating that they were mediated by extramitochondrial mechanisms. Extra ATP utilized for K+ uptake in response to phenylephrine was apparently of glycolytic rather than mitochondrial origin. We propose that α-adrenergic-induced lactate production is secondary to an enhanced operation of the plasma membrane (Na+,K+)-ATPase. [ABSTRACT FROM AUTHOR]

Bacterial formate-nitrite transporters ( FNT) regulate the metabolic flow of small weak mono-acids derived from anaerobic mixed-acid fermentation, such as formate, and further transport nitrite and hydrosulfide. The eukaryotic Plasmodium falciparum FNT is vital for the malaria parasite by its ability to release the larger l-lactate substrate as the metabolic end product of anaerobic glycolysis in symport with protons preventing cytosolic acidification. However, the molecular basis for substrate discrimination by FNTs has remained unclear. Here, we identified a size-selective FNT substrate filter region around an invariant lysine at the bottom of the periplasmic/extracellular vestibule. The selectivity filter is reminiscent of the aromatic/arginine constriction of aquaporin water and solute channels regarding composition, location in the protein, and the size-selection principle. Bioinformatics support an adaptation of the eukaryotic FNT selectivity filter to accommodate larger physiologically relevant substrates. Mutations that affect the diameter at the filter site predictably modulated substrate selectivity. The shape of the vestibule immediately above the filter region further affects selectivity. This study indicates that eukaryotic FNTs evolved to transport larger mono-acid substrates, especially l-lactic acid as a product of energy metabolism. [ABSTRACT FROM AUTHOR]

Angiogenic endothelial cells and tumour cells can survive under hypoxic conditions and even proliferate and migrate in a low-oxygen environment. In both cell types, high rates of glycolysis (i.e. conversion of glucose to lactate) and glutaminolysis provide most of the required biosynthetic intermediates and energy to support sprouting and cell division without coupling to oxidative phosphorylation. This metabolic preference is observed under hypoxic conditions, but also in situations in which oxygen is present. In the case of tumour cells, this is known as the Warburg effect and is largely governed by oncogenes. In endothelial cells lining tumour blood vessels, the option of respiration-independent metabolism allows the neovasculature to resist the hostile environment of fluctuating oxygen tension (ranging from severe hypoxia to quasi-normal levels of oxygen). In addition, accumulation in tumours of lactate, the end-product of glycolysis, largely contributes to the angiogenic phenotype through inhibition of prolyl hydroxylase 2 and the activation of HIF1α and NFκB. Activation of the latter in a hypoxia-independent manner leads to the increased production of interleukin-8/ CXCL8 which drives the autocrine stimulation of endothelial cell proliferation and maturation of neovessels. In conclusion, the addiction of proliferating endothelial cells for glucose and glutamine as fuels and the driving force of lactate to promote angiogenesis provide novel potential treatment options without the disadvantages of conventional anti-angiogenic drugs. [ABSTRACT FROM AUTHOR]

Abstract: Maitotoxin (MTX), a potent polyether marine biotoxin, induces Ca2+ entry in different mammalian cells by activation of Ca2+ channels. The identity and modulation of the MTX-activated Ca2+ entry pathway is not known. In this work, we show, for the first time, that glucose and lactate can modulate the excitability of spermatogenic cell MTX-activated Ca2+ channels. Physiological and pharmacological evidences indicate that glucose and lactate differentially affect MTX-activated Ca2+ entry mainly through changes that these substrates induce on intracellular Ca2+ stores and the concentration of intracellular Ca2+ ([Ca2+]i) in spermatogenic cells. Our findings strongly suggest that MTX-activated Ca2+ channels in spermatogenic cells can be regulated by a Ca2+-CaM-dependent protein kinase. [Copyright &y& Elsevier]

Ischaemia decreases mitochondrial NADH oxidation, activates glycolysis, increases the NADH/NAD+ ratio, and causes lactate production. The mechanisms that regulate anaerobic glycolysis and the NADH/NAD+ ratio during ischaemia are unclear. Although continuous measurements of metabolic fluxes and NADH/NAD+ in cytosol and mitochondria are not possible in vivo with current experimental techniques, computational models can be used to predict these variables by simulations with in silico experiments. Such predictions were obtained using a mathematical model of cellular metabolism in perfused myocardium. This model, which distinguishes cytosolic and mitochondrial domains, incorporates key metabolic species and processes associated with energy transfer. Simulation of metabolic responses to mild, moderate and severe ischaemia in large animals showed that mitochondrial NADH/NAD+ was rapidly reset to higher values in proportion to the reduced O2 delivery and myocardial oxygen consumption . Cytosolic NADH/NAD+, however, showed a biphasic response, with a sharp initial increase that was due to activation of glycogen breakdown and glycolysis, and corresponded with lactate production. Whereas the rate of glycolysis and the malate–aspartate shuttle had a significant effect on the cytosolic NADH/NAD+, their effects on the mitochondrial NADH/NAD+ were minimal. In summary, model simulations of the metabolic response to ischaemia showed that mitochondrial NADH/NAD+ is primarily determined by O2 consumption, while cytosolic NADH/NAD+ is largely a function of glycolytic flux during the initial phase, and is determined by mitochondrial NADH/NAD+ and the malate–aspartate shuttle during the steady state. [ABSTRACT FROM AUTHOR]

When hepatocytes from fasted rats were incubated with 10 mM glucose, there was a linear accumulation of lactate and pyruvate for about 80 rain after which steady-state concentrations of these metabolites became established, The rate of glycolysis, determined with [6-³H]glucose, was constant over the entire incubation period and was 50% greater than that calculated from carbon balance studies. This suggests that one-third of the glycolytic products formed were recycled to glucose. To enable study of the factors associated with the generation and maintenance of the lactate steady state and to measure accurately the carbon balance, incubations were performed using supraphysiological concentrations of glucose (20- 80 mM). Under these conditions the initial rate of lactate accumulation and its concentration at steady state were shown to be dependent on the concentration of extracellular glucose. Rates of glycolysis were also measured using 40 mM 16-³H]glucose and [U-14C]glucose added alone. or in combination with a steady-state lactate concentration (3 mM). There was no effect on the rate of glycolysis determined with [6-³H]glucose, even when lactate was present in the medium. The difference in rates between measurements with the two isotopes reflects the apparent degree of glucose recycling which in the absence and presence of added lactate increased from 0.26 to 0.54 μmol C3, equivalents min-1 · g-1 respectively. Identical studies employing [U-14C]lactate showed that glucose and CO2 were the major products of lactate metabolism under steady-state conditions and that the formation of lactate from [U-14C]glucose exactly balanced the rate of lactate removal as a result of oxidation and gluconeogenesis. These studies provide evidence for the concomitant operation of glycolysis and gluconeogenesis, even in the presence of high glucose concentrations. They also demonstrate that lactate steady states are achieved not by the cessation of glycolysis but rather by the removal of lactate and pyruvate at a rate equal to that of their production. [ABSTRACT FROM AUTHOR]

Changes in the rates of glucose, lactate and pyruvate production following infusion of glucagons were studied in isolated livers from fed or fasted rats perfused with non-recirculating Krebs­Henseleit bicarbonate buffer. 1. Evidence was presented that under these experimental conditions, the release of lactate plus pyruvate into the perfusate represents 80–90% of the total glycolytic flux: oxidation of pyruvate derived from glucose and/or glycogen accounts for the remaining 10–20%, whereas recycling of pyruvate to glucose is negligible. 2. In the presence of glucagons, rates of lactate plus pyruvate production were diminished to less than 30% in the fed state (glycogen as substrate) and to less than 10% in the fasted state (glucose as substrate). Rates of pyruvate oxidation were unchanged. Although recycling of pyruvate to glucose was enhanced, it could account for not more than 20% of the decrease in lactate plus pyruvate production. The data indicate a strong inhibition of the substrate flux through glycolysis. 3. The glucagons concentration for half-maximal inhibition of glycolysis was 0.2 nM, independent of the substrate (glucose or glycogen) and the nutritional state. The effective concentrations were within the physiological range of glucagons concentrations reported for portal venous blood. 4. Transient state analyses indicated that the inhibition of glycolysis precedes the stimulation of glycogenolysis. When after a delay glycogenolysis was accelerated, it was followed by a transient stimulation of glycolysis. The stimulatory component in the glucagons effect on glycolysis was diminished in glycogen-depleted livers and when glucose was the main substrate. The coordinated control of glycolysis and glycogenolysis by glucagons and the interaction of the two processes in the transient state are discussed. [ABSTRACT FROM AUTHOR]

The heat production of human erythrocytes was measured on a flow microcalorimeter with simultaneous analyses of lactate and other metabolites. The heat production connected with the lactate formation was about 17 kcal (71 kJ) per mol lactate formed which corresponded to the sum of heat production due to the formation of lactate from glucose and the heat production due to neutralization. The heat production rate increased as the pH of the suspension increased, corresponding to the increase in lactate formation. Glycolytic inhibitors such as fluoride and moniodoacetate caused a decrease in the rate of heat production, whereas arsenate induced a large transient increase in heat production associated with a transient increase in lactate formation. Decrease in pyruvate concentration was usually associated with increase in heat production, although the decreased pyruvate concentration was coupled with formation of 2,3-bisphosphoglycerate. When inosine, dihydroxyacetone or D-glyceraldehyde was used as a substrate, an increase in the heat production rate was observed. Addition of methylene blue caused an oxygen uptake which was accompanied by a remarkable increase in heat production rate corresponding to about 160 kcal (670 kJ) per mol oxygen consumed. The value for heat production in red cells in the above-mentioned metabolic conditions was considered in relation to earlier known data on free energy and enthalpy changes of the different metabolic steps in the glycolytic pathway. [ABSTRACT FROM AUTHOR]

Abstract: Maitotoxin (MTX), a potent polyether marine biotoxin, induces Ca2+ entry in different mammalian cells by activation of Ca2+ channels. The identity and modulation of the MTX-activated Ca2+ entry pathway is not known. In this work, we show, for the first time, that glucose and lactate can modulate the excitability of spermatogenic cell MTX-activated Ca2+ channels. Physiological and pharmacological evidences indicate that glucose and lactate differentially affect MTX-activated Ca2+ entry mainly through changes that these substrates induce on intracellular Ca2+ stores and the concentration of intracellular Ca2+ ([Ca2+]i) in spermatogenic cells. Our findings strongly suggest that MTX-activated Ca2+ channels in spermatogenic cells can be regulated by a Ca2+-CaM-dependent protein kinase. [Copyright &y& Elsevier]

Kluyveromyces marxianus is the most suitable fungus for inulinase industrial production. However, the underlying transcriptional activation mechanism of the inulinase gene (INU1) is hitherto unclear. Here, we undertook genetic and biochemical analyses to elucidate that a glycolysis regulator KmGcr1p with unique Q‐rich repeats is the key transcriptional activator of INU1. We determined that INU1 and glycolytic genes share similar transcriptional activation patterns and that inulinase activity is induced by fermentable carbon sources including the hydrolysis products of inulin (fructose and glucose), which suggests a novel model of product feedback activation. Furthermore, all four CT‐boxes in the INU1 promoter are important for KmGcr1p DNA‐binding in vitro, but the most downstream CT‐box 1 primarily confers upstream activating sequence activity in vivo. More intriguingly, the use of artificial and natural GCR1 mutants suggests that the Q‐rich repeats act as a functional module to maintain KmGcr1p transcriptional activity by contributing to its solubility and DNA‐binding affinity. Altogether, this study uncovers a novel transcriptional activation mechanism for the inulinase gene, that is different from the previous understanding for filamentous fungi, but might have universal significance among inulinase‐producing yeasts, thereby leading to a better understanding of the regulation mechanism of yeast inulinase genes. [ABSTRACT FROM AUTHOR]