RESUMO
Lysine lactylation is a post-translational modification that links cellular metabolism to protein function. Here, we find that AARS1 functions as a lactate sensor that mediates global lysine lacylation in tumor cells. AARS1 binds to lactate and catalyzes the formation of lactate-AMP, followed by transfer of lactate to the lysince acceptor residue. Proteomics studies reveal a large number of AARS1 targets, including p53 where lysine 120 and lysine 139 in the DNA binding domain are lactylated. Generation and utilization of p53 variants carrying constitutively lactylated lysine residues revealed that AARS1 lactylation of p53 hinders its liquid-liquid phase separation, DNA binding, and transcriptional activation. AARS1 expression and p53 lacylation correlate with poor prognosis among cancer patients carrying wild type p53. ß-alanine disrupts lactate binding to AARS1, reduces p53 lacylation, and mitigates tumorigenesis in animal models. We propose that AARS1 contributes to tumorigenesis by coupling tumor cell metabolism to proteome alteration.
Assuntos
Carcinogênese , Ácido Láctico , Proteína Supressora de Tumor p53 , Animais , Feminino , Humanos , Camundongos , Carcinogênese/metabolismo , Carcinogênese/genética , Linhagem Celular Tumoral , Ácido Láctico/metabolismo , Lisina/metabolismo , Neoplasias/metabolismo , Neoplasias/genética , Processamento de Proteína Pós-Traducional , Proteína Supressora de Tumor p53/metabolismo , MasculinoRESUMO
Proton-coupled monocarboxylate transporters MCT1-4 catalyze the transmembrane movement of metabolically essential monocarboxylates and have been targeted for cancer treatment because of their enhanced expression in various tumors. Here, we report five cryo-EM structures, at resolutions of 3.0-3.3 Å, of human MCT1 bound to lactate or inhibitors in the presence of Basigin-2, a single transmembrane segment (TM)-containing chaperon. MCT1 exhibits similar outward-open conformations when complexed with lactate or the inhibitors BAY-8002 and AZD3965. In the presence of the inhibitor 7ACC2 or with the neutralization of the proton-coupling residue Asp309 by Asn, similar inward-open structures were captured. Complemented by structural-guided biochemical analyses, our studies reveal the substrate binding and transport mechanism of MCTs, elucidate the mode of action of three anti-cancer drug candidates, and identify the determinants for subtype-specific sensitivities to AZD3965 by MCT1 and MCT4. These findings lay out an important framework for structure-guided drug discovery targeting MCTs.
Assuntos
Antineoplásicos/farmacologia , Transportadores de Ácidos Monocarboxílicos/antagonistas & inibidores , Transportadores de Ácidos Monocarboxílicos/química , Simportadores/antagonistas & inibidores , Simportadores/química , Sequência de Aminoácidos , Animais , Basigina/química , Sítios de Ligação , Microscopia Crioeletrônica , Humanos , Ligantes , Modelos Moleculares , Transportadores de Ácidos Monocarboxílicos/ultraestrutura , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Prótons , Pirimidinonas/química , Pirimidinonas/farmacologia , Ratos , Homologia Estrutural de Proteína , Especificidade por Substrato , Simportadores/ultraestrutura , Tiofenos/química , Tiofenos/farmacologiaRESUMO
Mg2+ is the most abundant divalent cation in metazoans and an essential cofactor for ATP, nucleic acids, and countless metabolic enzymes. To understand how the spatio-temporal dynamics of intracellular Mg2+ (iMg2+) are integrated into cellular signaling, we implemented a comprehensive screen to discover regulators of iMg2+ dynamics. Lactate emerged as an activator of rapid release of Mg2+ from endoplasmic reticulum (ER) stores, which facilitates mitochondrial Mg2+ (mMg2+) uptake in multiple cell types. We demonstrate that this process is remarkably temperature sensitive and mediated through intracellular but not extracellular signals. The ER-mitochondrial Mg2+ dynamics is selectively stimulated by L-lactate. Further, we show that lactate-mediated mMg2+ entry is facilitated by Mrs2, and point mutations in the intermembrane space loop limits mMg2+ uptake. Intriguingly, suppression of mMg2+ surge alleviates inflammation-induced multi-organ failure. Together, these findings reveal that lactate mobilizes iMg2+ and links the mMg2+ transport machinery with major metabolic feedback circuits and mitochondrial bioenergetics.
Assuntos
Retículo Endoplasmático/metabolismo , Ácido Láctico/metabolismo , Magnésio/metabolismo , Animais , Células COS , Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Chlorocebus aethiops , Retículo Endoplasmático/fisiologia , Feminino , Células HeLa , Células Hep G2 , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/metabolismoRESUMO
RLR-mediated type I IFN production plays a pivotal role in elevating host immunity for viral clearance and cancer immune surveillance. Here, we report that glycolysis, which is inactivated during RLR activation, serves as a barrier to impede type I IFN production upon RLR activation. RLR-triggered MAVS-RIG-I recognition hijacks hexokinase binding to MAVS, leading to the impairment of hexokinase mitochondria localization and activation. Lactate serves as a key metabolite responsible for glycolysis-mediated RLR signaling inhibition by directly binding to MAVS transmembrane (TM) domain and preventing MAVS aggregation. Notably, lactate restoration reverses increased IFN production caused by lactate deficiency. Using pharmacological and genetic approaches, we show that lactate reduction by lactate dehydrogenase A (LDHA) inactivation heightens type I IFN production to protect mice from viral infection. Our study establishes a critical role of glycolysis-derived lactate in limiting RLR signaling and identifies MAVS as a direct sensor of lactate, which functions to connect energy metabolism and innate immunity.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteína DEAD-box 58/antagonistas & inibidores , Proteína DEAD-box 58/metabolismo , Ácido Láctico/farmacologia , Receptores de Superfície Celular/antagonistas & inibidores , Receptores de Superfície Celular/metabolismo , Animais , Feminino , Glicólise , Células HEK293 , Humanos , Interferon beta/metabolismo , L-Lactato Desidrogenase/genética , L-Lactato Desidrogenase/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Células RAW 264.7 , Receptores Imunológicos , Transdução de Sinais/efeitos dos fármacos , TransfecçãoRESUMO
Metabolism has been shown to control peripheral immunity, but little is known about its role in central nervous system (CNS) inflammation. Through a combination of proteomic, metabolomic, transcriptomic, and perturbation studies, we found that sphingolipid metabolism in astrocytes triggers the interaction of the C2 domain in cytosolic phospholipase A2 (cPLA2) with the CARD domain in mitochondrial antiviral signaling protein (MAVS), boosting NF-κB-driven transcriptional programs that promote CNS inflammation in experimental autoimmune encephalomyelitis (EAE) and, potentially, multiple sclerosis. cPLA2 recruitment to MAVS also disrupts MAVS-hexokinase 2 (HK2) interactions, decreasing HK enzymatic activity and the production of lactate involved in the metabolic support of neurons. Miglustat, a drug used to treat Gaucher and Niemann-Pick disease, suppresses astrocyte pathogenic activities and ameliorates EAE. Collectively, these findings define a novel immunometabolic mechanism that drives pro-inflammatory astrocyte activities, outlines a new role for MAVS in CNS inflammation, and identifies candidate targets for therapeutic intervention.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Astrócitos/metabolismo , Encefalomielite Autoimune Experimental/metabolismo , Fosfolipases A2 Secretórias/metabolismo , 1-Desoxinojirimicina/análogos & derivados , 1-Desoxinojirimicina/farmacologia , 1-Desoxinojirimicina/uso terapêutico , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/patologia , Encéfalo/metabolismo , Encéfalo/patologia , Células Cultivadas , Encefalomielite Autoimune Experimental/tratamento farmacológico , Feminino , Hexoquinase/metabolismo , Humanos , Ácido Láctico/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Fosfolipases A2 Secretórias/genéticaRESUMO
RNA splicing is involved in cancer initiation and progression, but how it influences host antitumor immunity in the metabolically abnormal tumor microenvironment (TME) remains unclear. Here, we demonstrate that lactate modulates Foxp3-dependent RNA splicing to maintain the phenotypic and functional status of tumor-infiltrating regulatory T (Treg) cells via CTLA-4. RNA splicing in Treg cells was correlated with the Treg cell signatures in the TME. Ubiquitin-specific peptidase 39 (USP39), a component of the RNA splicing machinery, maintained RNA-splicing-mediated CTLA-4 expression to control Treg cell function. Mechanistically, lactate promoted USP39-mediated RNA splicing to facilitate CTLA-4 expression in a Foxp3-dependent manner. Moreover, the efficiency of CTLA-4 RNA splicing was increased in tumor-infiltrating Treg cells from patients with colorectal cancer. These findings highlight the immunological relevance of RNA splicing in Treg cells and provide important insights into the environmental mechanism governing CTLA-4 expression in Treg cells.
Assuntos
Neoplasias , Linfócitos T Reguladores , Humanos , Antígeno CTLA-4 , Fatores de Transcrição Forkhead/genética , Ácido Láctico/metabolismo , Linfócitos do Interstício Tumoral , Neoplasias/genética , Neoplasias/metabolismo , Microambiente Tumoral , Proteases Específicas de Ubiquitina/metabolismoRESUMO
Inflammatory epithelial diseases are spurred by the concomitant dysregulation of immune and epithelial cells. How these two dysregulated cellular compartments simultaneously sustain their heightened metabolic demands is unclear. Single-cell and spatial transcriptomics (ST), along with immunofluorescence, revealed that hypoxia-inducible factor 1α (HIF1α), downstream of IL-17 signaling, drove psoriatic epithelial remodeling. Blocking HIF1α in human psoriatic lesions ex vivo impaired glycolysis and phenocopied anti-IL-17 therapy. In a murine model of skin inflammation, epidermal-specific loss of HIF1α or its target gene, glucose transporter 1, ameliorated epidermal, immune, vascular, and neuronal pathology. Mechanistically, glycolysis autonomously fueled epithelial pathology and enhanced lactate production, which augmented the γδ T17 cell response. RORγt-driven genetic deletion or pharmacological inhibition of either lactate-producing enzymes or lactate transporters attenuated epithelial pathology and IL-17A expression in vivo. Our findings identify a metabolic hierarchy between epithelial and immune compartments and the consequent coordination of metabolic processes that sustain inflammatory disease.
Assuntos
Glicólise , Subunidade alfa do Fator 1 Induzível por Hipóxia , Interleucina-17 , Animais , Humanos , Interleucina-17/metabolismo , Interleucina-17/imunologia , Camundongos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Pele/imunologia , Pele/patologia , Pele/metabolismo , Células Th17/imunologia , Células Th17/metabolismo , Transportador de Glucose Tipo 1/metabolismo , Transportador de Glucose Tipo 1/genética , Psoríase/imunologia , Psoríase/metabolismo , Epitélio/imunologia , Epitélio/metabolismo , Camundongos Knockout , Transdução de Sinais/imunologia , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/genética , Modelos Animais de Doenças , Ácido Láctico/metabolismo , Doença Crônica , Inflamação/imunologia , Camundongos Endogâmicos C57BLRESUMO
Cancer cells consume glucose and secrete lactate in culture. It is unknown whether lactate contributes to energy metabolism in living tumors. We previously reported that human non-small-cell lung cancers (NSCLCs) oxidize glucose in the tricarboxylic acid (TCA) cycle. Here, we show that lactate is also a TCA cycle carbon source for NSCLC. In human NSCLC, evidence of lactate utilization was most apparent in tumors with high 18fluorodeoxyglucose uptake and aggressive oncological behavior. Infusing human NSCLC patients with 13C-lactate revealed extensive labeling of TCA cycle metabolites. In mice, deleting monocarboxylate transporter-1 (MCT1) from tumor cells eliminated lactate-dependent metabolite labeling, confirming tumor-cell-autonomous lactate uptake. Strikingly, directly comparing lactate and glucose metabolism in vivo indicated that lactate's contribution to the TCA cycle predominates. The data indicate that tumors, including bona fide human NSCLC, can use lactate as a fuel in vivo.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/metabolismo , Ácido Láctico/metabolismo , Neoplasias Pulmonares/metabolismo , Animais , Análise Química do Sangue , Linhagem Celular Tumoral , Ciclo do Ácido Cítrico , Modelos Animais de Doenças , Feminino , Ácidos Glicéricos/metabolismo , Xenoenxertos , Humanos , Masculino , Camundongos , Transportadores de Ácidos Monocarboxílicos/genética , Transportadores de Ácidos Monocarboxílicos/metabolismo , Transplante de Neoplasias , Simportadores/genética , Simportadores/metabolismoRESUMO
Intracellular Mg2+ (iMg2+) is bound with phosphometabolites, nucleic acids, and proteins in eukaryotes. Little is known about the intracellular compartmentalization and molecular details of Mg2+ transport into/from cellular organelles such as the endoplasmic reticulum (ER). We found that the ER is a major iMg2+ compartment refilled by a largely uncharacterized ER-localized protein, TMEM94. Conventional and AlphaFold2 predictions suggest that ERMA (TMEM94) is a multi-pass transmembrane protein with large cytosolic headpiece actuator, nucleotide, and phosphorylation domains, analogous to P-type ATPases. However, ERMA uniquely combines a P-type ATPase domain and a GMN motif for ERMg2+ uptake. Experiments reveal that a tyrosine residue is crucial for Mg2+ binding and activity in a mechanism conserved in both prokaryotic (mgtB and mgtA) and eukaryotic Mg2+ ATPases. Cardiac dysfunction by haploinsufficiency, abnormal Ca2+ cycling in mouse Erma+/- cardiomyocytes, and ERMA mRNA silencing in human iPSC-cardiomyocytes collectively define ERMA as an essential component of ERMg2+ uptake in eukaryotes.
Assuntos
Adenosina Trifosfatases , ATPases do Tipo-P , Animais , Camundongos , Humanos , Adenosina Trifosfatases/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Transporte Biológico , ATPases do Tipo-P/metabolismo , Cálcio/metabolismo , ATPases Transportadoras de Cálcio do Retículo SarcoplasmáticoRESUMO
Lactate has long been considered a cellular waste product. However, we found that as extracellular lactate accumulates, it also enters the mitochondrial matrix and stimulates mitochondrial electron transport chain (ETC) activity. The resulting increase in mitochondrial ATP synthesis suppresses glycolysis and increases the utilization of pyruvate and/or alternative respiratory substrates. The ability of lactate to increase oxidative phosphorylation does not depend on its metabolism. Both L- and D-lactate are effective at enhancing ETC activity and suppressing glycolysis. Furthermore, the selective induction of mitochondrial oxidative phosphorylation by unmetabolized D-lactate reversibly suppressed aerobic glycolysis in both cancer cell lines and proliferating primary cells in an ATP-dependent manner and enabled cell growth on respiratory-dependent bioenergetic substrates. In primary T cells, D-lactate enhanced cell proliferation and effector function. Together, these findings demonstrate that lactate is a critical regulator of the ability of mitochondrial oxidative phosphorylation to suppress glucose fermentation.
Assuntos
Metabolismo Energético , Ácido Láctico , Ácido Láctico/metabolismo , Transporte de Elétrons , Fosforilação Oxidativa , Glicólise/fisiologia , Trifosfato de Adenosina/metabolismoRESUMO
Lactate accumulates to a significant amount in glioblastomas (GBMs), the most common primary malignant brain tumor with an unfavorable prognosis. However, it remains unclear whether lactate is metabolized by GBMs. Here, we demonstrated that lactate rescued patient-derived xenograft (PDX) GBM cells from nutrient-deprivation-mediated cell death. Transcriptome analysis, ATAC-seq, and ChIP-seq showed that lactate entertained a signature of oxidative energy metabolism. LC/MS analysis demonstrated that U-13C-lactate elicited substantial labeling of TCA-cycle metabolites, acetyl-CoA, and histone protein acetyl-residues in GBM cells. Lactate enhanced chromatin accessibility and histone acetylation in a manner dependent on oxidative energy metabolism and the ATP-citrate lyase (ACLY). Utilizing orthotopic PDX models of GBM, a combined tracer experiment unraveled that lactate carbons were substantially labeling the TCA-cycle metabolites. Finally, pharmacological blockage of oxidative energy metabolism extended overall survival in two orthotopic PDX models in mice. These results establish lactate metabolism as a novel druggable pathway for GBM.
Assuntos
Glioblastoma , Acetilação , Animais , Linhagem Celular Tumoral , Epigênese Genética , Glioblastoma/genética , Glioblastoma/patologia , Histonas/metabolismo , Humanos , Ácido Láctico/metabolismo , CamundongosRESUMO
Tumor-infiltrating myeloid cells (TIMs) are crucial cell populations involved in tumor immune escape, and their functions are regulated by multiple epigenetic mechanisms. The precise regulation mode of RNA N6-methyladenosine (m6A) modification in controlling TIM function is still poorly understood. Our study revealed that the increased expression of methyltransferase-like 3 (METTL3) in TIMs was correlated with the poor prognosis of colon cancer patients, and myeloid deficiency of METTL3 attenuated tumor growth in mice. METTL3 mediated m6A modification on Jak1 mRNA in TIMs, the m6A-YTHDF1 axis enhanced JAK1 protein translation efficiency and subsequent phosphorylation of STAT3. Lactate accumulated in tumor microenvironment potently induced METTL3 upregulation in TIMs via H3K18 lactylation. Interestingly, we identified two lactylation modification sites in the zinc-finger domain of METTL3, which was essential for METTL3 to capture target RNA. Our results emphasize the importance of lactylation-driven METTL3-mediated RNA m6A modification for promoting the immunosuppressive capacity of TIMs.
Assuntos
Metiltransferases , Neoplasias , Adenosina/metabolismo , Animais , Humanos , Terapia de Imunossupressão , Metiltransferases/genética , Metiltransferases/metabolismo , Camundongos , Células Mieloides/metabolismo , RNA , Microambiente TumoralRESUMO
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.
Assuntos
Ácido Láctico , Psoríase , Camundongos , Animais , Ácido Láctico/metabolismo , Ácido Láctico/farmacologia , Pele/metabolismo , Macrófagos/metabolismo , Inflamação/metabolismo , Psoríase/metabolismoRESUMO
How the microaerobic pathogen Campylobacter jejuni establishes its niche and expands in the gut lumen during infection is poorly understood. Using 6-wk-old ferrets as a natural disease model, we examined this aspect of C. jejuni pathogenicity. Unlike mice, which require significant genetic or physiological manipulation to become colonized with C. jejuni, ferrets are readily infected without the need to disarm the immune system or alter the gut microbiota. Disease after C. jejuni infection in ferrets reflects closely how human C. jejuni infection proceeds. Rapid growth of C. jejuni and associated intestinal inflammation was observed within 2 to 3 d of infection. We observed pathophysiological changes that were noted by cryptic hyperplasia through the induction of tissue repair systems, accumulation of undifferentiated amplifying cells on the colon surface, and instability of HIF-1α in colonocytes, which indicated increased epithelial oxygenation. Metabolomic analysis demonstrated that lactate levels in colon content were elevated in infected animals. A C. jejuni mutant lacking lctP, which encodes an L-lactate transporter, was significantly decreased for colonization during infection. Lactate also influences adhesion and invasion by C. jejuni to a colon carcinoma cell line (HCT116). The oxygenation required for expression of lactate transporter (lctP) led to identification of a putative thiol-based redox switch regulator (LctR) that may repress lctP transcription under anaerobic conditions. Our work provides better insights into the pathogenicity of C. jejuni.
Assuntos
Infecções por Campylobacter , Campylobacter jejuni , Animais , Humanos , Camundongos , Ácido Láctico/metabolismo , Campylobacter jejuni/genética , Furões , Transportadores de Ácidos MonocarboxílicosRESUMO
While the intracellular-extracellular distribution of lactate has been suggested to play a critical role in the healthy and diseased brain, tools are lacking to noninvasively probe lactate in intracellular and extracellular spaces. Here, we show that, by measuring the diffusion of lactate with diffusion-weighted magnetic resonance (MR) spectroscopy in vivo and comparing it to the diffusion of purely intracellular metabolites, noninvasive quantification of extracellular and intracellular lactate fractions becomes possible. More specifically, we detect alterations of lactate diffusion in the APP/PS1 mouse model of Alzheimer's disease. Data modeling allows quantifying decreased extracellular lactate fraction in APP/PS1 mice as compared to controls, which is quantitatively confirmed with implanted enzyme-microelectrodes. The capability of diffusion-weighted MR spectroscopy to quantify extracellular-intracellular lactate fractions opens a window into brain metabolism, including in Alzheimer's disease.
Assuntos
Doença de Alzheimer , Encéfalo , Ácido Láctico , Animais , Ácido Láctico/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/diagnóstico por imagem , Encéfalo/metabolismo , Encéfalo/diagnóstico por imagem , Camundongos , Camundongos Transgênicos , Imagem de Difusão por Ressonância Magnética/métodos , Espaço Extracelular/metabolismo , Modelos Animais de Doenças , Espectroscopia de Ressonância Magnética/métodos , Masculino , Precursor de Proteína beta-Amiloide/metabolismoRESUMO
Lactate-proton symporter monocarboxylate transporter 1 (MCT1) facilitates lactic acid export from T cells. Here, we report that MCT1 is mandatory for the development of virus-specific CD8+ T cell memory. MCT1-deficient T cells were exposed to acute pneumovirus (pneumonia virus of mice, PVM) or persistent γ-herpesvirus (Murid herpesvirus 4, MuHV-4) infection. MCT1 was required for the expansion of virus-specific CD8+ T cells and the control of virus replication in the acute phase of infection. This situation prevented the subsequent development of virus-specific T cell memory, a necessary step in containing virus reactivation during γ-herpesvirus latency. Instead, persistent active infection drove virus-specific CD8+ T cells toward functional exhaustion, a phenotype typically seen in chronic viral infections. Mechanistically, MCT1 deficiency sequentially impaired lactic acid efflux from activated CD8+ T cells, caused an intracellular acidification inhibiting glycolysis, disrupted nucleotide synthesis in the upstream pentose phosphate pathway, and halted cell proliferation which, ultimately, promoted functional CD8+ T cell exhaustion instead of memory development. Taken together, our data demonstrate that MCT1 expression is mandatory for inducing T cell memory and controlling viral infection by CD8+ T cells.
Assuntos
Linfócitos T CD8-Positivos , Transportadores de Ácidos Monocarboxílicos , Simportadores , Animais , Camundongos , Transporte Biológico , Linfócitos T CD8-Positivos/metabolismo , Ácido Láctico/metabolismo , Simportadores/genética , Simportadores/metabolismo , Transportadores de Ácidos Monocarboxílicos/genética , Transportadores de Ácidos Monocarboxílicos/metabolismoRESUMO
Information processing imposes urgent metabolic demands on neurons, which have negligible energy stores and restricted access to fuel. Here, we discuss metabolic recruitment, the tissue-level phenomenon whereby active neurons harvest resources from their surroundings. The primary event is the neuronal release of K+ that mirrors workload. Astrocytes sense K+ in exquisite fashion thanks to their unique coexpression of NBCe1 and α2ß2 Na+/K+ ATPase, and within seconds switch to Crabtree metabolism, involving GLUT1, aerobic glycolysis, transient suppression of mitochondrial respiration, and lactate export. The lactate surge serves as a secondary recruiter by inhibiting glucose consumption in distant cells. Additional recruiters are glutamate, nitric oxide, and ammonium, which signal over different spatiotemporal domains. The net outcome of these events is that more glucose, lactate, and oxygen are made available. Metabolic recruitment works alongside neurovascular coupling and various averaging strategies to support the inordinate dynamic range of individual neurons.
Assuntos
Metabolismo Energético , Glicólise , Humanos , Metabolismo Energético/fisiologia , Glicólise/fisiologia , Glucose/metabolismo , Ácido Láctico/metabolismo , Encéfalo/metabolismoRESUMO
In neurons, fast axonal transport (FAT) of vesicles occurs over long distances and requires constant and local energy supply for molecular motors in the form of adenosine triphosphate (ATP). FAT is independent of mitochondrial metabolism. Indeed, the glycolytic machinery is present on vesicles and locally produces ATP, as well as nicotinamide adenine dinucleotide bonded with hydrogen (NADH) and pyruvate, using glucose as a substrate. It remains unclear whether pyruvate is transferred to mitochondria from the vesicles as well as how NADH is recycled into NAD+ on vesicles for continuous glycolysis activity. The optimization of a glycolytic activity test for subcellular compartments allowed the evaluation of the kinetics of vesicular glycolysis in the brain. This revealed that glycolysis is more efficient on vesicles than in the cytosol. We also found that lactate dehydrogenase (LDH) enzymatic activity is required for effective vesicular ATP production. Indeed, inhibition of LDH or the forced degradation of pyruvate inhibited ATP production from axonal vesicles. We found LDHA rather than the B isoform to be enriched on axonal vesicles suggesting a preferential transformation of pyruvate to lactate and a concomitant recycling of NADH into NAD+ on vesicles. Finally, we found that LDHA inhibition dramatically reduces the FAT of both dense-core vesicles and synaptic vesicle precursors in a reconstituted cortico-striatal circuit on-a-chip. Together, this shows that aerobic glycolysis is required to supply energy for vesicular transport in neurons, similar to the Warburg effect.
Assuntos
Glicólise , NAD , NAD/metabolismo , Glicólise/fisiologia , Axônios/metabolismo , Trifosfato de Adenosina/metabolismo , Piruvatos/metabolismoRESUMO
Endothelial cells differ from other cell types responsible for the formation of the vascular wall in their unusual reliance on glycolysis for most energy needs, which results in extensive production of lactate. We find that endothelium-derived lactate is taken up by pericytes, and contributes substantially to pericyte metabolism including energy generation and amino acid biosynthesis. Endothelial-pericyte proximity is required to facilitate the transport of endothelium-derived lactate into pericytes. Inhibition of lactate production in the endothelium by deletion of the glucose transporter-1 (GLUT1) in mice results in loss of pericyte coverage in the retina and brain vasculatures, leading to the blood-brain barrier breakdown and increased permeability. These abnormalities can be largely restored by oral lactate administration. Our studies demonstrate an unexpected link between endothelial and pericyte metabolisms and the role of endothelial lactate production in the maintenance of the blood-brain barrier integrity. In addition, our observations indicate that lactate supplementation could be a useful therapeutic approach for GLUT1 deficiency metabolic syndrome patients.
Assuntos
Barreira Hematoencefálica , Pericitos , Animais , Barreira Hematoencefálica/metabolismo , Células Endoteliais/metabolismo , Endotélio/metabolismo , Transportador de Glucose Tipo 1/genética , Transportador de Glucose Tipo 1/metabolismo , Humanos , Ácido Láctico/metabolismo , Camundongos , Pericitos/metabolismoRESUMO
Expression levels of the lactate-H+ cotransporter MCT4 (also known as SLC16A3) and its chaperone CD147 (also known as basigin) are upregulated in breast cancers, correlating with decreased patient survival. Here, we test the hypothesis that MCT4 and CD147 favor breast cancer invasion through interdependent effects on extracellular matrix (ECM) degradation. MCT4 and CD147 expression and membrane localization were found to be strongly reciprocally interdependent in MDA-MB-231 breast cancer cells. Overexpression of MCT4 and/or CD147 increased, and their knockdown decreased, migration, invasion and the degradation of fluorescently labeled gelatin. Overexpression of both proteins led to increases in gelatin degradation and appearance of the matrix metalloproteinase (MMP)-generated collagen-I cleavage product reC1M, and these increases were greater than those observed upon overexpression of each protein alone, suggesting a concerted role in ECM degradation. MCT4 and CD147 colocalized with invadopodia markers at the plasma membrane. They also colocalized with MMP14 and the lysosomal marker LAMP1, as well as partially with the autophagosome marker LC3, in F-actin-decorated intracellular vesicles. We conclude that MCT4 and CD147 reciprocally regulate each other and interdependently support migration and invasiveness of MDA-MB-231 breast cancer cells. Mechanistically, this involves MCT4-CD147-dependent stimulation of ECM degradation and specifically of MMP-mediated collagen-I degradation. We suggest that the MCT4-CD147 complex is co-delivered to invadopodia with MMP14.