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A metabolic coupling between glutamate and N-acetylaspartate measured by in vivo magnetic resonance spectroscopy has been recently reported in the literature with inconsistent findings. In this study, confounders originating from Pearson's spurious correlation of ratios and spectral correlation due to overlapping magnetic resonance spectroscopy signals of glutamate and N-acetylaspartate were practically eliminated to facilitate the determination of any metabolic link between glutamate and N-acetylaspartate in the human brain using in vivo magnetic resonance spectroscopy. In both occipital and medial prefrontal cortices of healthy individuals, correlations between glutamate and N-acetylaspartate were found to be insignificant. Our results do not lend support to a recent hypothesis that N-acetylaspartate serves as a significant reservoir for the rapid replenishment of glutamate during signaling or stress. [ABSTRACT FROM AUTHOR]

Background and AimSalidroside (SA) is the main active component of Rhodiola rosea L., with potential in treating cardiovascular and cerebrovascular diseases and cerebral ischemia. However, its efficacy and mechanism in cerebral ischemia remain unclear, particularly regarding its effect on glutamate (Glu) metabolism. In this paper, we aimed to investigate the efficacy of SA in treating cerebral ischemia and its pharmacological mechanism.Experimental procedureWe studied the effects of SA on SD rats with cerebral ischemia, evaluating neurobehavior, cerebral water content, infarct size, and brain microstructure. We also assessed its impact on glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), and glutamate transporter 1 (GLT-1) proteins using immunohistochemistry and Western blot. Additionally, we used SVGp12 cells to simulate cerebral ischemia and measured Glu levels and used Western blot to observe the level of GS and GLT-1.ResultsSA improved neural function, reduced infarct size, and regulated GSH and Glu levels in rats. In cell experiments, SA increased cell viability and decreased Glu concentration after ischemia induction. It also regulated the expression of GFAP, GS, and GLT-1.ConclusionSA alleviates cerebral ischemia-induced injury by acting on astrocytes, possibly through regulating the glutamate metabolic pathway.

Abstract The effects of evodiamine (EVO) on oral squamous cell carcinoma (OSCC) are not yet understood. Based on our earlier findings, we hypothesized that evodiamine may affect OSCC cell proliferation and glutamate metabolism by modulating the expression of EPRS (glutamyl‐prolyl‐tRNA synthetase 1). From GEPIA, we obtained EPRS expression data in patients with OSCC as well as survival prognosis data. An animal model using Cal27 cells in BALB/c nude mice was established. The expression of EPRS was assessed by immunofluorescence, Western blotting, and quantitative PCR. Glutamate measurements were performed to evaluate the impact of evodiamine on glutamate metabolism of Cal27 and SAS tumor cells. transient transfection techniques were used to knock down and modulate EPRS in these cells. EPRS is expressed at higher levels in OSCC than in normal tissues, and it predicts poor prognosis in patients. In a nude mouse xenograft model, evodiamine inhibited tumor growth and the expression of EPRS. Evodiamine impacted cell proliferation, glutamine metabolism, and EPRS expression on Cal27 and SAS cell lines. In EPRS knockdown cell lines, both cell proliferation and glutamine metabolism are suppressed. EPRS's overexpression partially restores evodiamine's inhibitory effects on cell proliferation and glutamine metabolism. This study provides crucial experimental evidence supporting the potential therapeutic application of evodiamine in treating OSCC. Evodiamine exhibits promising anti‐tumor effects by targeting EPRS to regulate glutamate metabolism.

Abstract DNA methylation is crucial for chromatin structure and gene expression and its aberrancies, including the global “hypomethylator phenotype”, are associated with cancer. Here we show that an underlying mechanism for this phenotype in the large proportion of the highly lethal brain tumor glioblastoma (GBM) carrying receptor tyrosine kinase gene mutations, involves the mechanistic target of rapamycin complex 2 (mTORC2), that is critical for growth factor signaling. In this scenario, mTORC2 suppresses the expression of the de novo DNA methyltransferase (DNMT3A) thereby inducing genome-wide DNA hypomethylation. Mechanistically, mTORC2 facilitates a redistribution of EZH2 histone methyltransferase into the promoter region of DNMT3A, and epigenetically represses the expression of DNA methyltransferase. Integrated analyses in both orthotopic mouse models and clinical GBM samples indicate that the DNA hypomethylator phenotype consistently reprograms a glutamate metabolism network, eventually driving GBM cell invasion and survival. These results nominate mTORC2 as a novel regulator of DNA hypomethylation in cancer and an exploitable target against cancer-promoting epigenetics.

The effects of evodiamine (EVO) on oral squamous cell carcinoma (OSCC) are not yet understood. Based on our earlier findings, we hypothesized that evodiamine may affect OSCC cell proliferation and glutamate metabolism by modulating the expression of EPRS (glutamyl‐prolyl‐tRNA synthetase 1). From GEPIA, we obtained EPRS expression data in patients with OSCC as well as survival prognosis data. An animal model using Cal27 cells in BALB/c nude mice was established. The expression of EPRS was assessed by immunofluorescence, Western blotting, and quantitative PCR. Glutamate measurements were performed to evaluate the impact of evodiamine on glutamate metabolism of Cal27 and SAS tumor cells. transient transfection techniques were used to knock down and modulate EPRS in these cells. EPRS is expressed at higher levels in OSCC than in normal tissues, and it predicts poor prognosis in patients. In a nude mouse xenograft model, evodiamine inhibited tumor growth and the expression of EPRS. Evodiamine impacted cell proliferation, glutamine metabolism, and EPRS expression on Cal27 and SAS cell lines. In EPRS knockdown cell lines, both cell proliferation and glutamine metabolism are suppressed. EPRS's overexpression partially restores evodiamine's inhibitory effects on cell proliferation and glutamine metabolism. This study provides crucial experimental evidence supporting the potential therapeutic application of evodiamine in treating OSCC. Evodiamine exhibits promising anti‐tumor effects by targeting EPRS to regulate glutamate metabolism. [ABSTRACT FROM AUTHOR]

DNA methylation is crucial for chromatin structure and gene expression and its aberrancies, including the global "hypomethylator phenotype", are associated with cancer. Here we show that an underlying mechanism for this phenotype in the large proportion of the highly lethal brain tumor glioblastoma (GBM) carrying receptor tyrosine kinase gene mutations, involves the mechanistic target of rapamycin complex 2 (mTORC2), that is critical for growth factor signaling. In this scenario, mTORC2 suppresses the expression of the de novo DNA methyltransferase (DNMT3A) thereby inducing genome-wide DNA hypomethylation. Mechanistically, mTORC2 facilitates a redistribution of EZH2 histone methyltransferase into the promoter region of DNMT3A, and epigenetically represses the expression of DNA methyltransferase. Integrated analyses in both orthotopic mouse models and clinical GBM samples indicate that the DNA hypomethylator phenotype consistently reprograms a glutamate metabolism network, eventually driving GBM cell invasion and survival. These results nominate mTORC2 as a novel regulator of DNA hypomethylation in cancer and an exploitable target against cancer-promoting epigenetics. [ABSTRACT FROM AUTHOR]

• Activating α2A-AR in hippocampus confered neuroprotection against sepsis-associated encephalopathy (SAE). • The neuroprotective effect of activating hippocampal α2A-AR was astrocyte specific. • Reducing glutamate excitatory neurotoxicity was the potential mechanism of the neuroprotective effect confered by astrocytic α2A-AR in hippocampus. Glutamate metabolism disorder is an important mechanism of sepsis-associated encephalopathy (SAE). Astrocytes regulate glutamate metabolism. In septic mice, α2A adrenoceptor (α2A-AR) activation in the central nervous system provides neuroprotection. α2A-ARs are expressed abundantly in hippocampal astrocytes. This study was performed to determine whether hippocampal astrocytic α2A-AR activation confers neuroprotection against SAE and whether this protective effect is astrocyte specific and achieved by the modulation of glutamate metabolism. Male C57BL/6 mice with and without α2A-AR knockdown were subjected to cecal ligation and puncture (CLP). They were treated with intrahippocampal guanfacine (an α2A-AR agonist) or intraperitoneal dexmedetomidine in the presence or absence of dihydrokainic acid [DHK; a glutamate transporter 1 (GLT-1) antagonist] and/or UCPH-101 [a glutamate/aspartate transporter (GLAST) antagonist]. Hippocampal tissue was collected for the measurement of astrocyte reactivity, GLT-1 and GLAST expression, and glutamate receptor subunit 2B (GluN2B) phosphorylation. In vivo real-time extracellular glutamate concentrations in the hippocampus were measured by ultra-performance liquid chromatography tandem mass spectrometry combined with microdialysis, and in vivo real-time hippocampal glutamatergic neuron excitability was assessed by calcium imaging. The mice were subjected to the Barnes maze and fear conditioning tests to assess their learning and memory. Golgi staining was performed to assess changes in the hippocampal synaptic structure. In vitro, primary astrocytes with and without α2A-AR knockdown were stimulated with lipopolysaccharide (LPS) and treated with guanfacine or dexmedetomidine in the presence or absence of 8-bromo- cyclic adenosine monophosphate (8-Br-cAMP, a cAMP analog). LPS-treated primary and BV2 microglia were also treated with guanfacine or dexmedetomidine. Astrocyte reactivity, PKA catalytic subunit, GLT-1 an GLAST expression were determined in primary astrocytes. Interleukin-1β, interleukin-6 and tumor necrosis factor-alpha in the medium of microglia culture were measured. CLP induced synaptic injury, impaired neurocognitive function, increased astrocyte reactivity and reduced GLT-1 and GLAST expression in the hippocampus of mice. The extracellular glutamate concentration, phosphorylation of GluN2B at Tyr-1472 and glutamatergic neuron excitability in the hippocampus were increased in the hippocampus of septic mice. Intraperitoneal dexmedetomidine or intrahippocampal guanfacine administration attenuated these effects. Hippocampal astrocytes expressed abundant α2A-ARs; expression was also detected in neurons but not microglia. Specific knockdown of α2A-ARs in hippocampal astrocytes and simultaneous intrahippocampal DHK and UCPH-101 administration blocked the neuroprotective effects of dexmedetomidine and guanfacine. Intrahippocampal administration of DHK or UCPH-101 alone had no such effect. In vitro, guanfacine or dexmedetomidine inhibited astrocyte reactivity, reduced PKA catalytic subunit expression, and increased GLT-1 and GLAST expression in primary astrocytes but not in primary astrocytes that received α2A-AR knockdown or were treated with 8-Br-cAMP. Guanfacine or dexmedetomidine inhibited microglial reactivity in BV2 but not primary microglia. Our results suggest that neurocognitive protection against SAE after hippocampal α2A-AR activation is astrocyte specific. This protection may involve the inhibition of astrocyte reactivity and alleviation of glutamate neurotoxicity, thereby reducing synaptic injury. The cAMP/protein kinase A (PKA) signaling pathway is a potential cellular mechanism by which activating α2A-AR modulates astrocytic function. [ABSTRACT FROM AUTHOR]

Abstract—The involvement of inflammation, disturbances of glutamate metabolism, and oxidative stress in the pathogenesis of schizophrenia and affective disorders has been proven by numerous studies. It seems relevant to assess the role of these systems in the development of prodromal stages of schizophrenia in juvenile patients with depression. The aim of this study was to investigate the association between markers of inflammation, energy and glutamate metabolism, and antioxidant defense with the clinical features of patients with adolescent depression. 74 males aged 16–25 years with a first depressive episode (F32.1-2, F32.38, F32.8) were observed: 32 subjects with attenuated positive symptoms, 22 persons with attenuated negative symptoms, 20 individuals without attenuated schizophrenia symptoms. The control group included 57 mentally healthy adults aged 19–25 years. The activity of leukocyte elastase and α1-proteinase inhibitor, the level of autoantibodies to S100B and myelin basic protein in plasma and the activity of cytochrome c-oxidase, glutamate dehydrogenase, glutathione reductase and glutathione-S-transferase in platelets were determined. Within each clinical group, differences in the profiles of immunological and biochemical parameters were identified. Division of patients into clusters according to all biological parameters showed different level of inflammation and changes of glutamate metabolism and antioxidant defense related to the features of psychopathological symptoms. The results confirm the connection of the studied metabolic systems and their different involvement to the development of adolescent depression with different psychopathological structure, which is important to assess the role of these systems in the trajectory of the disease and early therapeutic correction. [ABSTRACT FROM AUTHOR]

Background: Glutamate and glutamine are the most abundant amino acids in the blood and play a crucial role in cell survival in the nervous system. Various transporters found in cell and mitochondrial membranes, such as the solute carriers (SLCs) superfamily, are responsible for maintaining the balance of glutamate and glutamine in the synaptic cleft and within cells. This balance affects the metabolism of glutamate and glutamine as non‐essential amino acids. Aims: This review aims to provide an overview of the transporters and enzymes associated with glutamate and glutamine in neuronal cells. Discussion: We delve into the function of glutamate and glutamine in the nervous system by discussing the transporters involved in the glutamate‐glutamine cycle and the key enzymes responsible for their mutual conversion. Additionally, we highlight the role of glutamate and glutamine as carbon and nitrogen donors, as well as their significance as precursors for the synthesis of reduced glutathione (GSH). Conclusion: Glutamate and glutamine play a crucial role in the brain due to their special effects. It is essential to focus on understanding glutamate and glutamine metabolism to comprehend the physiological behavior of nerve cells and to treat nervous system disorders and cancer. [ABSTRACT FROM AUTHOR]

Excitation/inhibition (E/I) balance is carefully maintained by the nervous system. The neurotransmitter GABA has been reported to be co‐released with its sole precursor, the neurotransmitter glutamate. The genetic and circuitry mechanisms to establish the balance between GABAergic and glutamatergic signaling have not been fully elucidated. Caenorhabditis elegans DVB is an excitatory GABAergic motoneuron that drives the expulsion step in the defecation motor program. We show here that in addition to UNC‐47, the vesicular GABA transporter, DVB also expresses EAT‐4, a vesicular glutamate transporter. UBR‐1, a conserved ubiquitin ligase, regulates DVB activity by suppressing a bidirectional inhibitory glutamate signaling. Loss of UBR‐1 impairs DVB Ca2+ activity and expulsion frequency. These impairments are fully compensated by the knockdown of EAT‐4 in DVB. Further, glutamate‐gated chloride channels GLC‐3 and GLC‐2/4 receive DVB's glutamate signals to inhibit DVB and enteric muscle activity, respectively. These results implicate an intrinsic cellular mechanism that promotes the inherent asymmetric neural activity. We propose that elevated glutamate in ubr‐1 mutants, being the cause of the E/I shift, potentially contributes to Johanson Blizzard syndrome. Synopsis: This study reveals an unexpected role and mechanism of the E3 ubiquitin ligase UBR‐1 in the balance between excitatory GABA and inhibitory glutamate transmission in the C. elegans defecation motor circuit. Functionally conserved UBR‐1 promotes the expulsion step in the C. elegans defecation motor program.UBR‐1 regulates Ca2+ activities of the excitatory GABAergic DVB neuron and its downstream enteric muscles.Glutamate homeostasis is required for the functional regulation of UBR‐1.UBR‐1 maintains primary excitatory GABAergic activity by suppressing bidirectional inhibitory glutamate signaling through GLC‐3 and GLC‐2/4 in the DVB neuron and enteric muscle, respectively. [ABSTRACT FROM AUTHOR]

Introduction: Glutamate is a representative taste molecule with an umami flavor and is a major nutrient found abundantly in nature. Furthermore, it plays a significant role in the human body as a key metabolic intermediate and neurotransmitter. Therefore, the divergence of glutamate functions among populations during their evolution is of particular interest with a hypothesis that the genetic variation can lead to understanding divergence in taste perception. To elucidate variation in glutamate applications and to deepen our understanding of taste perception, we examined the nucleotide diversity of genes associated with glutamate sensing and metabolism among human populations. Methods: We first established 67 genes related to glutamate sensing and metabolism based on the database and literature survey. Then, for those genes, we used a population genomics approach based on ten populations over 76,156 human genomes in the gnomAD database. Results: Statistical tests of means and medians of the minor allele frequencies did not show any significant difference among populations. However, we observed substantial differences between two functional groups, glutamate sensing and glutamate metabolism, in populations of Latino/admixed American, Ashkenazi Jewish, and Others. Interestingly, we could find significant differences between the African population and the East Asian population at the single nucleotide polymorphism level of glutamate metabolism genes, but no clear differences were noted in glutamate-sensing genes. These suggest that glutamate-sensing genes are under the functional constraint compared to glutamate metabolism genes. Conclusion: Thus, glutamate-sensing genes and metabolism genes have a contrasting mode of the evolution, and glutamate-sensing genes are conservatively evolved, indicating its functional importance. [ABSTRACT FROM AUTHOR]

Introduction: Bacterial metabolic environment influences antibiotic killing efficacy. Thus, a full understanding for the metabolic resistance mechanisms is especially important to combat antibiotic-resistant bacteria. Methods: Isobaric tags for relative and absolute quantification-based proteomics approach was employed to compare proteomes between ceftazidime-resistant and -sensitive Edwarsiella tarda LTB4 (LTB4-RCAZ and LTB4-S, respectively). Results: This analysis suggested the possibility that the ceftazidime resistance mediated by depressed glucose is implemented through an inefficient metabolic flux from glycolysis, the pyruvate cycle, glutamate metabolism to purine metabolism. The inefficient flux was demonstrated by the reduced expression of genes and the decreased activity of enzymes in the four metabolic pathways. However, supplement upstream glucose and downstream guanosine separately restored ceftazidime killing, which not only supports the conclusion that the inefficient metabolic flux is responsible for the resistance, but also provides an effective approach to reverse the resistance. In addition, the present study showed that ceftazidime is bound to pts promoter in E. tarda. Discussion: Our study highlights the way in fully understanding metabolic resistance mechanisms and establishing metabolites-based metabolic reprogramming to combat antibiotic resistance. [ABSTRACT FROM AUTHOR]

New antibiotics are unquestionably needed to fight the emergence and spread of multidrug-resistant bacteria. To date, antibiotics targeting bacterial central metabolism have been poorly investigated. By determining the minimal inhibitory concentration (MIC) of desmethylphosphinothricin (Glu-γ-PH), an analogue of glutamate with a phosphinic moiety replacing the γ-carboxyl group, we previously showed its promising antibacterial activity on Escherichia coli. Herein, we synthetized and determined the growth inhibition exerted on E. coli by an L-Leu dipeptide derivative of Glu-γ-PH (L-Leu-D,L-Glu-γ-PH). Furthermore, we compared the growth inhibition obtained with this dipeptide with that exerted by the free amino acid, i.e., Glu-γ-PH, and by their phosphonic and non-desmethylated analogues. All the tested compounds were more effective when assayed in a chemically-defined minimal medium. The dipeptide L-Leu-D,L-Glu-γ-PH had a significantly improved antibacterial activity (2 μg/mL), at a concentration between the non-desmethytaled (0.1 μg/mL) and the phosphonic (80 μg/mL) analogues. Also, in Bacillus subtilis, the dipeptide L-Leu-D,L-Glu-γ-PH displayed an activity comparable to that of the antibiotic amoxicillin. This work highlights the antibacterial relevance of the phosphinic pharmacophore and proposes new avenues for the development of novel antimicrobial drugs containing the phosphinic moiety. [ABSTRACT FROM AUTHOR]

Vibrio splendidus is the main opportunistic pathogen that causes skin ulcer syndrome in Apostichopus japonicus. hppDIn the present study, mutant V. splendidus with an in-frame deletion of hppDV.s. (MTVs) was constructed. The median lethal doses of wild-type V. splendidus (WTVs) and MTVs were 5.129 × 106 and 2.606 × 1010 CFU mL−1, respectively. RNA-Seq was performed using WTVs and MTVs cells at different growth stages to explore the mechanisms of the pathogenesis mediated by hppDV.s. Gene Ontology analysis showed that the expression levels of 105 genes involved in amino acid metabolism and protein binding were remarkably different between MTVs and WTVs. Kyoto Encyclopedia of Genes and Genomes analysis showed that the pathways of glutamate metabolism and flagellum assembly involved in biofilm formation and swarming motility were suppressed in MTVs. Correspondingly, the swarming motility, biofilm formation and colonisation of MTVs were remarkably decreased compared with those of WTVs. The results showed that 4-hppD catalyses tyrosine into fumarate, which could enhance glutamate metabolism and ATP production; promote flagellum assembly through the TCA cycle and lead to higher swarming, biofilm formation and colonisation abilities, to contribute to the pathogenesis of V. splendidus.

Background: Glaucoma is the leading cause of irreversible blindness, and the loss of retinal ganglion cells (RGCs) is the most important pathological feature. During the progression of glaucoma, glutamate content in the optic nerve increases, and glutamate-induced excitotoxicity will aggregate the damage and death of RGCs. We have previously reported that olfactory ensheathing cells (OECs) transplantation preserved the visual function of the glaucoma model but the mechanism is unknown. Methods: Adult Long-Evans rats were used in the present study and injecting magnetic microspheres was used to establish a glaucoma model in rats. Optokinetic response test and Pattern electroretinogram recording were used to assess the visual functions of rats. RT-PCR, immunofluorescence, and co-culture experiments were performed to investigate the therapeutic effects and mechanisms of OECs for glaucoma. Results: In the glaucoma model, increased glutamate content and the damage of astrocytes (AC) and RGCs were observed. OECs transplantation reduced the glutamate concentration in the optic nerve, alleviated the apoptosis of AC and RGCs, and protected the visual function of the glaucoma model. Furthermore, we found that OECs possessed a stronger capacity to metabolize excessive glutamate compared with AC and Müller glia. OECs could improve the glutamate microenvironment of the optic nerve to prevent AC and RGCs from glutamate-induced excitotoxicity in glaucoma. And the recovery of AC function further supported the survival of RGCs. Conclusions: We demonstrate that OECs transplantation could play a neuroprotective role by regulating the glutamate microenvironment in glaucoma. [ABSTRACT FROM AUTHOR]

Rhizosphere functional microorganisms play an important role in the bioremediation of heavy metal-polluted farmlands, however, further research is needed to investigate the effects of exogenous inoculation of functional strains on key bacterial communities and metabolites in cadmium (Cd)-polluted wheat farmlands. This study investigated the effects of the urease-producing bacterium Enterobacter bugandensis TJ6 combined with polyamine-producing bacterium Serratia marcescens X43 on Cd uptake by wheat and its microbiological and soi biolological mechanisms. The results showed that strains TJ6+X43 reduced (95.1 %) the Cd content by secreting urease and polyamines and inducing the precipitation of Cd to form CdCO 3 and Cd(OH) 2. The combined strains increased (22.7 %) the dry weight and reduced (37.2 %) the Cd content in wheat grains. Moreover, the DTPA-Cd content, the NH 4 +/NO 3 - ratio and the urease activity were increased in the presence of strains TJ6+X43. The combined strains reduced the diversity of bacterial communities, but increased the relative abundances of key strains such as Gemmatimonas, Ramlibacter, Sporacetigenium, Pseudomonas, Microvirga, and Nitrospira in the wheat rhizosphere soil. In addition, the contents of glutamate, glutathione, L-ribulose, arginine, nitrite, spermine, isocitrate, and D-xylulose were also increased. More importantly, glutamate metabolism was roused to induce rhizosphere metabolites and functional bacterial communities to synergistically inactivate Cd. The results showed that inoculation with heavy metal-immobilizing bacteria can result in the activation of key functional bacteria and the regulation of metabolite production in wheat rhizosphere soil to immobilize heavy metals, which has broad potential in the bioremediation of wheat fields and ensuring food security. [Display omitted] • Strains TJ6+X43 reduced Cd content by secreting urease and polyamines in solution. • Strains TJ6+X43 reduced the Cd content in wheat grains. • Rhizosphere key bacterial community such as Gemmatimonas and Ramlibacter were roused. • Exogenous inoculation of strains TJ6+X43 affected the composition of root exudates. • Glutamate metabolism was the link between rhizosphere ket bacteria and metabolites. [ABSTRACT FROM AUTHOR]

New antibiotics are unquestionably needed to fight the emergence and spread of multidrug-resistant bacteria. To date, antibiotics targeting bacterial central metabolism have been poorly investigated. By determining the minimal inhibitory concentration (MIC) of desmethylphosphinothricin (Glu-γ-PH), an analogue of glutamate with a phosphinic moiety replacing the γ-carboxyl group, we previously showed its promising antibacterial activity on Escherichia coli. Herein, we synthetized and determined the growth inhibition exerted on E. coli by an L-Leu dipeptide derivative of Glu-γ-PH (L-Leu-D,L-Glu-γ-PH). Furthermore, we compared the growth inhibition obtained with this dipeptide with that exerted by the free amino acid, i.e., Glu-γ-PH, and by their phosphonic and non-desmethylated analogues. All the tested compounds were more effective when assayed in a chemically-defined minimal medium. The dipeptide L-Leu-D,L-Glu-γ-PH had a significantly improved antibacterial activity (2 μg/mL), at a concentration between the non-desmethytaled (0.1 μg/mL) and the phosphonic (80 μg/mL) analogues. Also, in Bacillus subtilis, the dipeptide L-Leu-D,L-Glu-γ-PH displayed an activity comparable to that of the antibiotic amoxicillin. This work highlights the antibacterial relevance of the phosphinic pharmacophore and proposes new avenues for the development of novel antimicrobial drugs containing the phosphinic moiety.

Lipid transporter protein apolipoprotein E (APOE) has contributed to functional studies of various organ functions. Animals with ApoE knockout (KO) have been used to study atherosclerosis and hyperlipidemia while an increasing number of researchers have recently focused on the association of ApoE with hearing loss. A study found that ApoE KO mice experience sensorineural hearing loss and hair cell loss, but the exact mechanism is unclear. To explore the potential relationship between ApoE and hearing loss, we used HEI-OC1 cells (House Ear Institute-Organ of Corti) with Corti apparatus properties to reveal cell changes after ApoE knockout by combined transcriptome and metabolomic analysis. We found that glutamate deficiency, caused by reduced expression of glutamine transporter proteins, was a key correlate of basal metabolism and that inadequate glutamate causes apoptosis by reducing the cells' resistance to external damage. Our study provides a reference mechanism for hearing loss due to ApoE KO. [ABSTRACT FROM AUTHOR]

Maternal sleep deprivation (MSD) has emerged as a significant public health concern, yet its effects on offspring metabolism remain poorly understood. This study investigated the metabolomic implications of MSD on offspring cognitive development, with a particular focus on alterations in glutamate metabolism. Pregnant rats were subjected to sleep deprivation during late gestation. Plasma and brain samples from their offspring were collected at different postnatal days (P1, P7, P14, and P56) and analyzed using untargeted metabolomics with liquid chromatography-mass spectrometry. Metabolomic analysis revealed significant differences in various amino acids, including L-glutamate, L-phenylalanine, L-tyrosine, and L-tryptophan, which are crucial for cognitive function. Subsequent differential analysis and partial least squares discriminant analysis (sPLS-DA) demonstrated a gradual reduction in these metabolic differences in the brain as the offspring underwent growth and development. KEGG pathway analysis revealed differential regulation of several pathways, including alanine, aspartate, and glutamate metabolism, glutathione metabolism, arginine biosynthesis, aminoacyl-tRNA biosynthesis, histidine metabolism, and taurine and hypotaurine metabolism, at different developmental stages. Mantel and Spearman analyses indicated that the observed changes in metabolites in MSD progeny may be related to various gut microbes, Ruminococcus_1 , Ruminococcaceae_UCG-005 , and Eubacterium_coprostanoligenes_group. Biochemical assays further demonstrated developmental changes in the L-glutamate metabolic pathway. Collectively, these findings suggest that MSD not only affects maternal well-being but also has enduring metabolic consequences for offspring, particularly impacting pathways linked to cognitive function. This highlights the importance of addressing maternal sleep health to mitigate potential long-term consequences for offspring.

Increased levels of lactoferrin (Lf) are present in the aged brain and in the lesions of various neurodegenerative diseases, including Parkinson's disease (PD), and may contribute to the cascade of events involved in neurodevelopment and neuroprotection. However, whether Lf originates from astrocytes and functions within either the normal or pathological brain are unknown. Here, we employed mice with specific knockout of the astrocyte lactoferrin gene (named Lf-cKO) to explore its specific roles in the pathological process of PD. We observed a decrease in tyrosine hydroxylase-positive cells, mitochondrial dysfunction of residual dopaminergic neurons, and motor deficits in Lf-cKO mice, which were significantly aggravated after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment. To further explore how astrocytic lactoferrin deficiency exacerbated PD-like manifestation in MPTP-treated mice, the critical molecules involved in endoplasmic reticulum (ER)-mitochondria contacts and signaling pathways were investigated. In vitro and in vivo models, we found an aberrant level of effects implicated in glutamate and calcium homeostasis, mitochondrial morphology and functions, mitochondrial dynamics, and mitochondria-associated ER membranes, accompanied by signs of oxidative stress and ER stress, which increase the fragility of dopaminergic neurons. These findings confirm the existence of astrocytic Lf and its influence on the fate of dopaminergic neurons by regulating glutamate/calcium metabolism and ER-mitochondria signaling. Our findings may be a promising target for the treatment of PD., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Invasive Lobular Carcinoma (ILC) is a subtype of breast cancer characterized by distinct biological features, and limited glucose uptake coupled with increased reliance on amino acid and lipid metabolism. Our prior studies highlight the importance of glutamate as a key regulator of ILC tumor growth and therapeutic response. Here we examine the expression of four key proteins involved in glutamate transport and metabolism - SLC3A2, SLC7A11, GPX4, and GLUD1/2 - in a racially diverse cohort of 72 estrogen receptor-positive (ER+) ILC and 50 ER+ invasive ductal carcinoma, no special type (IDC/NST) patients with primary disease. All four proteins are associated with increased tumor size in ILC, but not IDC/NST, with SLC3A2 also specifically linked to shorter overall survival and the presence of comorbidities in ILC. Notably, GLUD1/2 expression is associated with ER expression in ILC, and is most strongly associated with increased tumor size and stage in Black women with ILC from our cohort and TCGA. We further explore the effects of GLUD1 inhibition in endocrine therapy-resistant ILC cells using the small-molecule inhibitor R162, which reduces ER protein levels, increases reactive oxygen species, and inhibits oxidative phosphorylation. These findings highlight a potentially important role for glutamate metabolism in ILC, particularly for Black women, and position several of these glutamate-handling proteins as potential targets for therapeutic intervention in ILC., Competing Interests: Conflict of interest: Authors declare no conflict of interest.

Polypyrimidine tract-binding protein 1 (PTBP1) regulates numerous alternative splicing events during tumor progression and neurogenesis. Previously, PTBP1 downregulation was reported to convert astrocytes into functional neurons; however, how PTBP1 regulates astrocytic physiology remains unclear. In this study, we revealed that PTBP1 modulated glutamate uptake via ATP1a2, a member of Na+/K+-ATPases, and glutamate transporters in astrocytes. Ptbp1 knockdown altered mitochondrial function and energy metabolism, which involved PTBP1 regulating mitochondrial redox homeostasis via the succinate dehydrogenase (SDH)/Nrf2 pathway. The malfunction of glutamate transporters following Ptbp1 knockdown resulted in enhanced excitatory synaptic transmission in the cortex. Notably, we developed a biomimetic cationic triblock polypeptide system, i.e., polyethylene glycol 44 -polylysine 30 -polyleucine 10 (PEG 44 -PLL 30 -PLLeu 10) with astrocytic membrane coating to deliver Ptbp1 siRNA in vitro and in vivo , which approach allowed Ptbp1 siRNA to efficiently cross the blood-brain barrier and target astrocytes in the brain. Collectively, our findings suggest a framework whereby PTBP1 serves as a modulator in glutamate transport machinery, and indicate that biomimetic methodology is a promising route for in vivo siRNA delivery. [ABSTRACT FROM AUTHOR]

Mutations in cancer reprogram amino acid metabolism to drive tumor growth, but the molecular mechanisms are not well understood. Using an unbiased proteomic screen, we identified mTORC2 as a critical regulator of amino acid metabolism in cancer via phosphorylation of the cystine-glutamate antiporter xCT. mTORC2 phosphorylates serine 26 at the cytosolic N terminus of xCT, inhibiting its activity. Genetic inhibition of mTORC2, or pharmacologic inhibition of the mammalian target of rapamycin (mTOR) kinase, promotes glutamate secretion, cystine uptake, and incorporation into glutathione, linking growth factor receptor signaling with amino acid uptake and utilization. These results identify an unanticipated mechanism regulating amino acid metabolism in cancer, enabling tumor cells to adapt to changing environmental conditions.

Metabolic shift and antibiotic resistance have been reported in Pseudomonas aeruginosa. However, the global metabolic characteristics remain largely unknown. The present study characterizes the central carbon metabolism and its effect on other metabolic pathways in cefoperazone-sulbactam (SCF)-resistant P. aeruginosa (PA-RSCF). GC-MS-based metabolomics shows a repressed central carbon metabolism in PA-RSCF, which is confirmed by measuring expression of genes and activity of enzymes in the metabolism. Furthermore, expression of the genes that encode the enzymes for the first step of fatty acid biosynthesis, glutamate metabolism, and electron transport chain is reduced, confirmed by their enzymatic activity assay, and the key enzyme for riboflavin metabolism is also reduced, indicating the decreased metabolic flux to the four related metabolic pathways. Moreover, the role of the reduced riboflavin metabolism, being related to ROS generation, in SCF resistance is explored. Exogenous H2O2 potentiates SCF-mediated killing in a dose-dependent manner, suggesting that the decreased ROS resulted from the reduced riboflavin metabolism that contributed to the resistance. These results indicate that the repressed central carbon metabolism and related riboflavin metabolism contribute to SCF resistance, but increasing ROS can restore SCF sensitivity. These findings characterize the repressed central carbon metabolism and its effect on other metabolic pathways as the global metabolic features in PA-RSCF. [ABSTRACT FROM AUTHOR]

Metabolic shift and antibiotic resistance have been reported in Pseudomonas aeruginosa. However, the global metabolic characteristics remain largely unknown. The present study characterizes the central carbon metabolism and its effect on other metabolic pathways in cefoperazone-sulbactam (SCF)-resistant P. aeruginosa (PA-RSCF). GC-MS-based metabolomics shows a repressed central carbon metabolism in PA-RSCF, which is confirmed by measuring expression of genes and activity of enzymes in the metabolism. Furthermore, expression of the genes that encode the enzymes for the first step of fatty acid biosynthesis, glutamate metabolism, and electron transport chain is reduced, confirmed by their enzymatic activity assay, and the key enzyme for riboflavin metabolism is also reduced, indicating the decreased metabolic flux to the four related metabolic pathways. Moreover, the role of the reduced riboflavin metabolism, being related to ROS generation, in SCF resistance is explored. Exogenous H2O2 potentiates SCF-mediated killing in a dose-dependent manner, suggesting that the decreased ROS resulted from the reduced riboflavin metabolism that contributed to the resistance. These results indicate that the repressed central carbon metabolism and related riboflavin metabolism contribute to SCF resistance, but increasing ROS can restore SCF sensitivity. These findings characterize the repressed central carbon metabolism and its effect on other metabolic pathways as the global metabolic features in PA-RSCF.

Abstract Background Chemokine C–C motif ligand 2 (CCL2) is one of the most widely recognised proinflammatory chemokines in cognitive disorders. Currently, CCL2-targeting drugs are extremely limited. Thus, this study aimed to explore the neuroprotection afforded by naringin in CCL2-induced cognitive impairment in rats. Methods Before the CCL2 intra-hippocampal injection, rats were treated with naringin for 3 consecutive days via intraperitoneal injection. Two days post-surgery, the Morris water maze (MWM) and novel object recognition (NORT) tests were performed to detect spatial learning and memory and object cognition, respectively. Nissl staining and dUTP nick-end labelling (TUNEL) staining were performed to assess histopathological changes in the hippocampus. Commercial kits were used to measure the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the content of malondialdehyde (MDA). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine the relative mRNA expression of interleukin 1β, (IL-1β), interleukin 6 (IL-6), glutamate/aspartate transporter (GLAST), glutamate transporter-1 (GLT-1), phosphate-activated glutaminase (PAG), cysteine aspartic acid-specific protease 8 (caspase-8), cysteine aspartic acid-specific protease 3 (caspase-3), cell lymphoma/leukaemia-2 (Bcl-2), and Bcl-2 associated X protein (Bax). Results In the MWM, the average escape latency and average swimming distance were significantly reduced and the crossing times were increased in the naringin-treated groups, compared with the CCL2 group. The NORT results revealed that, compared with the CCL2 rats, the discrimination index in the naringin-treated rats increased significantly. Nissl and TUNEL staining revealed that naringin protected the structure and survival of the neurons in the CA1 zone of the hippocampus. In the naringin-treated groups, the SOD and GSH-Px activities were increased, whereas the MDA levels were decreased. Furthermore, in the naringin-treated groups, the relative mRNA expression of IL-1β and IL-6 was significantly decreased; GLAST and GLT-1 mRNA expression levels were increased, whereas PAG was decreased. In the naringin-treated groups, the relative mRNA expression levels of caspase-8, caspase-3, and Bax were decreased, whereas that of Bcl-2 was increased. Conclusion Collectively, these data indicated that naringin alleviated the CCL2-induced cognitive impairment. The underlying mechanisms could be associated with the inhibition of neuroinflammation, oxidative stress, apoptosis, and the regulation of glutamate metabolism.

Glutamate is the main excitatory neurotransmitter in the brain, and its excitatory neurotoxicity is closely related to the occurrence and development of Alzheimer's disease. However, increasing evidence shows that in the process of Alzheimer's disease, glutamate is not only limited to its excitotoxicity as a neurotransmitter but also related to the disorder of its metabolic balance. The balance of glutamate metabolism in the brain is an important determinant of central nervous system health, and the maintenance of this balance is closely related to glutamate uptake, glutamate circulation, intracellular mitochondrial transport, and mitochondrial metabolism. In this paper, we intend to elaborate the key role of mitochondrial glutamate metabolism in the pathogenesis of Alzheimer's disease and review glutamate metabolism in mitochondria as a potential target in the treatment of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

(−)-Epigallocatechin-3-gallate (EGCG) is the main bioactive catechin in green tea. The antitumor activity of EGCG has been confirmed in various types of cancer, including lung cancer. However, the precise underlying mechanisms are still largely unclear. In the present study, we investigated the metabolite changes in A549 cells induced by EGCG in vitro utilizing liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. The result revealed 33 differentially expressed metabolites between untreated and 80 μM EGCG-treated A549 cells. The altered metabolites were involved in the metabolism of glucose, amino acid, nucleotide, glutathione, and vitamin. Two markedly altered pathways, including glycine, serine and threonine metabolism and alanine, aspartate and glutamate metabolism, were identified by MetaboAnalyst 5.0 metabolic pathway analysis. These results may provide potential clues for the intramolecular mechanisms of EGCG's effect on A549 cells. Our study may contribute to future molecular mechanistic studies of EGCG and the therapeutic application of EGCG in cancer management. [ABSTRACT FROM AUTHOR]

(−)-Epigallocatechin-3-gallate (EGCG) is the main bioactive catechin in green tea. The antitumor activity of EGCG has been confirmed in various types of cancer, including lung cancer. However, the precise underlying mechanisms are still largely unclear. In the present study, we investigated the metabolite changes in A549 cells induced by EGCG in vitro utilizing liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. The result revealed 33 differentially expressed metabolites between untreated and 80 μM EGCG-treated A549 cells. The altered metabolites were involved in the metabolism of glucose, amino acid, nucleotide, glutathione, and vitamin. Two markedly altered pathways, including glycine, serine and threonine metabolism and alanine, aspartate and glutamate metabolism, were identified by MetaboAnalyst 5.0 metabolic pathway analysis. These results may provide potential clues for the intramolecular mechanisms of EGCG’s effect on A549 cells. Our study may contribute to future molecular mechanistic studies of EGCG and the therapeutic application of EGCG in cancer management.

Lipid transporter protein apolipoprotein E (APOE) has contributed to functional studies of various organ functions. Animals with ApoE knockout (KO) have been used to study atherosclerosis and hyperlipidemia while an increasing number of researchers have recently focused on the association of ApoE with hearing loss. A study found that ApoE KO mice experience sensorineural hearing loss and hair cell loss, but the exact mechanism is unclear. To explore the potential relationship between ApoE and hearing loss, we used HEI-OC1 cells (House Ear Institute-Organ of Corti) with Corti apparatus properties to reveal cell changes after ApoE knockout by combined transcriptome and metabolomic analysis. We found that glutamate deficiency, caused by reduced expression of glutamine transporter proteins, was a key correlate of basal metabolism and that inadequate glutamate causes apoptosis by reducing the cells’ resistance to external damage. Our study provides a reference mechanism for hearing loss due to ApoE KO.

Glutamate and dopamine hypotheses are leading theories of the pathophysiology of schizophrenia. Multiple lines of evidence suggest that dopaminergic and glutamatergic dysfunction is an underlying mechanism in schizophrenia. Since currently available antipsychotic drugs have significant untoward side effects, identification of new neuroprotective compounds from the medicinal plants may prove beneficial in neurodegenerative disorders. In our previous investigation we have isolated, characterized and reported a novel bioactive compound viz. 3-(3, 4-dimethoxy phenyl)-1-(4-methoxy phenyl) prop-2-en-1-one from the Celastrus paniculatus (CP) is used for the current clinical intervention of schizophrenia disease. The present study is mainly aimed to evaluate the neuroprotective potential of the above bioactive compound against ketamine-induced schizophrenia with particular reference to glutamate metabolism using in vivo and in silico methods. The decrease in glutamine content and the activity levels of glutamate dehydrogenase, glutamine synthetase, and glutaminase in different regions of the rat brain suggests lowered oxidative deamination and lowered mobilization of glutamate towards glutamine formation during ketamine-induced schizophrenia. Pre-treatment with the plant compound reversed the alterations in glutamate metabolism and restored the normal glutamatergic neurotransmission akin to the reference drug, clozapine. In addition, the compound has shown strong interaction and exhibited the highest binding energies against selected NMDA receptors with the lowest inhibition constant than the reference drug. Recoveries of these parameters during anti-schizophrenic treatment suggest that administration of plant compound might offer neuroprotection by interrupting the pathological cascade of glutamatergic neurotransmission that occurs during schizophrenia.

The endothelial cells of the blood–brain barrier participate in the regulation of glutamate concentrations in the brain interstitial fluid by taking up brain glutamate. However, endothelial glutamate metabolism has not been characterized, nor is its role in brain glutamate homeostasis and endothelial energy production known. The aim of this study was to investigate endothelial glutamate dehydrogenase (GDH) expression and glutamate metabolism and probe its functional significance. The primary brain endothelial cells were isolated from bovine and mouse brains, and human brain endothelial cells were derived from induced pluripotent stem cells. GDH expression on the protein level and GDH function were investigated in the model systems using western blotting, confocal microscopy, 13C‐glutamate metabolism, and Seahorse assay. In this study, it was shown that GDH was expressed in murine and bovine brain capillaries and in cultured primary mouse and bovine brain endothelial cells as well as in human‐induced pluripotent stem cell‐derived endothelial cells. The endothelial GDH expression was confirmed in brain capillaries from mice carrying a central nervous system‐specific GDH knockout. Endothelial cells from all tested species metabolized 13C‐glutamate to α‐ketoglutarate, which subsequently entered the tricarboxylic acid (TCA)‐cycle. Brain endothelial cells maintained mitochondrial oxygen consumption rates, when supplied with glutamate alone, whereas glutamate supplied in addition to glucose did not lead to additional oxygen consumption. In conclusion, brain endothelial cells directly take up and metabolize glutamate and utilize the resulting α‐ketoglutarate in the tricarboxylic acid cycle to ultimately yield ATP if glucose is unavailable. [ABSTRACT FROM AUTHOR]

Mitochondrial cristae, infoldings of the mitochondrial inner membrane, undergo aberrant changes in their architecture with age. However, the underlying molecular mechanisms and their contribution to brain aging are largely elusive. Here, we observe an age-dependent accumulation of Glu-5′tsRNA-CTC, a transfer-RNA-derived small RNA (tsRNA), derived from nuclear-encoded tRNAGlu in the mitochondria of glutaminergic neurons. Mitochondrial Glu-5′tsRNA-CTC disrupts the binding of mt-tRNALeu and leucyl-tRNA synthetase2 (LaRs2), impairing mt-tRNALeu aminoacylation and mitochondria-encoded protein translation. Mitochondrial translation defects disrupt cristae organization, leading to damaged glutaminase (GLS)-dependent glutamate formation and reduced synaptosomal glutamate levels. Moreover, reduction of Glu-5′tsRNA-CTC protects aged brains from age-related defects in mitochondrial cristae organization, glutamate metabolism, synaptic structures, and memory. Thus, beyond illustrating a physiological role for normal mitochondrial cristae ultrastructure in maintaining glutamate levels, our study defines a pathological role for tsRNAs in brain aging and age-related memory decline. [Display omitted] • Aging induces cytoplasmic localization of angiogenin to produce Glu-5′tsRNA-CTC • Glu-5′tsRNA-CTC disrupts mitochondrial translation and cristae organization • Cristae ultrastructure is required to maintain glutamate homeostasis in the brain • ASO targeting Glu-5′tsRNA-CTC rescues memory decline in aged mice Li et al. demonstrate that aging induces dephosphorylation of angiogenin, leading to its mislocalization in the cytoplasm to cleave tRNAGlu. Mitochondrial accumulation of the cleavage product Glu-5′tsRNA-CTC impairs mitochondrial translation, cristae organization, and glutaminase-dependent glutamate biogenesis. Thus, Glu-5′tsRNA-CTC accelerates brain aging and ASO targeting Glu-5′tsRNA-CTC rescues age-related phenotypes in mice. [ABSTRACT FROM AUTHOR]

Thiamine (vitamin B1) is often deficient in oncopatients, particularly those undergoing chemotherapy. However, interaction between the thiamine deficiency and anticancer action of drugs has not been characterized. A major natural thiamine derivative, thiamine diphosphate (ThDP), is a coenzyme of central metabolism, also known to affect transcriptional activity of the master metabolic regulator and genome guardian p53. A direct transcriptional target of p53, p21, regulates cell cycle dynamics and DNA damage response. Our work focuses on dependence of the action of the DNA damaging anticancer drug cisplatin on metabolic regulation through p53/p21 axes and cellular thiamine status in human lung adenocarcinoma cells A549. These cells are used as a model of a hardly curable cancer, known to develop chemoresistance to platinum drugs, such as cisplatin. Compared to wild type (A549WT), a stable line with a 60% knockdown of p21 (A549p21–) is less sensitive to antiproliferative action of cisplatin. In contrast, in the thiamine-deficient medium, cisplatin impairs the viability of A549p21– cells more than that of A549WT cells. Analysis of the associated metabolic changes in the cells indicates that (i) p21 knockdown restricts the production of 2-oxoglutarate via glutamate oxidation, stimulating that within the tricarboxylic acid (TCA) cycle; (ii) cellular cisplatin sensitivity is associated with a 4-fold upregulation of glutamic-oxaloacetic transaminase (GOT2) by cisplatin; (iii) cellular cisplatin resistance is associated with a 2-fold upregulation of p53 by cisplatin. Correlation analysis of the p53 expression and enzymatic activities upon variations in cellular thiamine/ThDP levels indicates that p21 knockdown substitutes positive correlation of the p53 expression with the activity of 2-oxoglutarate dehydrogenase complex (OGDHC) for that with the activity of glutamate dehydrogenase (GDH). The knockdown also changes correlations of the levels of OGDHC, GDH and GOT2 with those of the malate and isocitrate dehydrogenases. Thus, a p53/p21-dependent change in partitioning of the glutamate conversion to 2-oxoglutarate through GOT2 or GDH, linked to NAD(P)-dependent metabolism of 2-oxoglutarate in affiliated pathways, adapts A549 cells to thiamine deficiency or cisplatin treatment. Cellular thiamine deficiency may interfere with antiproliferative action of cisplatin due to their common modulation of the p53/p21-dependent metabolic switch between the glutamate oxidation and transamination.

• Metabolic evolution of E. coli strain to grow on glutamate (Glu). • Understanding of Glu-metabolism in the evolved strain by the genetic approach. • Analysis of the flux distribution in key pathways in Glu-metabolism. • Manipulation of the rate-determining step in Glu-metabolism to improve the ethanol production. The biorefinery industry has processed lignocellulosic biomass for the production of bio-based products, which accompanies with the generation of proteins in waste streams. Glutamate (Glu) is a non-essential amino acid rich in various sources of protein waste. To explore the usefulness of Glu, Glu metabolism in Escherichia coli was deciphered by the genetic approach. Key pathways involving Glu catabolism were identified, and the analysis of end product profiles revealed the flux distribution in central metabolism. Using ethanol as an example, the rate-limiting reaction catalyzed by aspA was manipulated to adjust the cataplerostic flux in the tricarboxylic acid cycle. This in turn redistributes the flux between glycolysis and gluconeogenesis. Consequently, it improves the ethanol production which reaches 85% of the theoretical yield. Overall, the result of this study indicates that Glu is a new renewable source with a potential application in biorefinery and biotechnology. [Display omitted] [ABSTRACT FROM AUTHOR]

Thiamine (vitamin B1) is often deficient in oncopatients, particularly those undergoing chemotherapy. However, interaction between the thiamine deficiency and anticancer action of drugs has not been characterized. A major natural thiamine derivative, thiamine diphosphate (ThDP), is a coenzyme of central metabolism, also known to affect transcriptional activity of the master metabolic regulator and genome guardian p53. A direct transcriptional target of p53, p21, regulates cell cycle dynamics and DNA damage response. Our work focuses on dependence of the action of the DNA damaging anticancer drug cisplatin on metabolic regulation through p53/p21 axes and cellular thiamine status in human lung adenocarcinoma cells A549. These cells are used as a model of a hardly curable cancer, known to develop chemoresistance to platinum drugs, such as cisplatin. Compared to wild type (A549WT), a stable line with a 60% knockdown of p21 (A549p21–) is less sensitive to antiproliferative action of cisplatin. In contrast, in the thiamine-deficient medium, cisplatin impairs the viability of A549p21– cells more than that of A549WT cells. Analysis of the associated metabolic changes in the cells indicates that (i) p21 knockdown restricts the production of 2-oxoglutarate via glutamate oxidation, stimulating that within the tricarboxylic acid (TCA) cycle; (ii) cellular cisplatin sensitivity is associated with a 4-fold upregulation of glutamic-oxaloacetic transaminase (GOT2) by cisplatin; (iii) cellular cisplatin resistance is associated with a 2-fold upregulation of p53 by cisplatin. Correlation analysis of the p53 expression and enzymatic activities upon variations in cellular thiamine/ThDP levels indicates that p21 knockdown substitutes positive correlation of the p53 expression with the activity of 2-oxoglutarate dehydrogenase complex (OGDHC) for that with the activity of glutamate dehydrogenase (GDH). The knockdown also changes correlations of the levels of OGDHC, GDH and GOT2 with those of the malate and isocitrate dehydrogenases. Thus, a p53/p21-dependent change in partitioning of the glutamate conversion to 2-oxoglutarate through GOT2 or GDH, linked to NAD(P)-dependent metabolism of 2-oxoglutarate in affiliated pathways, adapts A549 cells to thiamine deficiency or cisplatin treatment. Cellular thiamine deficiency may interfere with antiproliferative action of cisplatin due to their common modulation of the p53/p21-dependent metabolic switch between the glutamate oxidation and transamination. [ABSTRACT FROM AUTHOR]

ABSTRACT Sodium-translocating NADH:quinone oxidoreductase (Na+-NQR) functions as a unique redox-driven sodium pump, generating membrane potential, which is related to aminoglycoside antibiotic resistance. However, whether it modulates other metabolisms to confer antibiotic resistance is unknown. The present study showed that loss of nqrA or nqrF led to differential metabolomes with elevated resistance to aminoglycoside antibiotics. Decreased alanine, aspartate, and glutamate metabolism and depressed abundance of alanine were characterized as the most impacted pathway and crucial biomarker, respectively. Further data showed that higher viability was detected in ΔnqrA and ΔnqrF mutant strains than their parent strain ATCC 33787 in the presence of gentamicin but recovered by exogenous l-alanine. It proceeds by the following events. The loss of nqrA or nqrF led to the decrease of membrane potential, ATPase activity, and then ATP and cyclic AMP (cAMP), which reduced the cAMP/CRP (cAMP receptor protein) complex. The reduced cAMP/CRP complex promoted l-alanine catabolism and inhibited l-alanine anabolism, causing reduced levels of alanine. Reduced alanine affected the expression of antiporter families Atp and Mnh genes. Our results suggest a novel mechanism by which the Na+-NQR system regulates antibiotic resistance via l-alanine metabolism in a cAMP/CRP complex-dependent manner. IMPORTANCE The Na+-NQR complex functions as a unique redox-driven sodium pump, generating membrane potential directly. However, whether it mediates generation of membrane potential indirectly is unknown. The present study shows that the Na+-NQR complex impacts membrane potential through other antiporter families Atp and Mnh. It proceeds by ATP and then cAMP/CRP regulon, which inhibits l-alanine catabolism and promotes l-alanine anabolism. When the Na+-NQR complex is reduced as in antibiotic-resistant bacteria, l-alanine is depressed, which is related to the antibiotic resistance phenotypes. However, exogenous l-alanine reverts the phenotype and promotes antibiotic-mediated killing. These findings suggest a novel mechanism by which the Na+-NQR system regulates antibiotic resistance via l-alanine metabolism in a cAMP/CRP complex-dependent manner.

Mitochondrial cristae, infoldings of the mitochondrial inner membrane, undergo aberrant changes in their architecture with age. However, the underlying molecular mechanisms and their contribution to brain aging are largely elusive. Here, we observe an age-dependent accumulation of Glu-5'tsRNA-CTC, a transfer-RNA-derived small RNA (tsRNA), derived from nuclear-encoded tRNA Glu in the mitochondria of glutaminergic neurons. Mitochondrial Glu-5'tsRNA-CTC disrupts the binding of mt-tRNA Leu and leucyl-tRNA synthetase2 (LaRs2), impairing mt-tRNA Leu aminoacylation and mitochondria-encoded protein translation. Mitochondrial translation defects disrupt cristae organization, leading to damaged glutaminase (GLS)-dependent glutamate formation and reduced synaptosomal glutamate levels. Moreover, reduction of Glu-5'tsRNA-CTC protects aged brains from age-related defects in mitochondrial cristae organization, glutamate metabolism, synaptic structures, and memory. Thus, beyond illustrating a physiological role for normal mitochondrial cristae ultrastructure in maintaining glutamate levels, our study defines a pathological role for tsRNAs in brain aging and age-related memory decline., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Glutamate dehydrogenase (GDH) releases ammonia in a reversible NAD(P)+-dependent oxidative deamination of glutamate that yields 2-oxoglutarate (2OG). In current perception, GDH contributes to Glu homeostasis and plays a significant role at the junction of carbon and nitrogen assimilation pathways. GDHs are members of a superfamily of ELFV (Glu/Leu/Phe/Val) amino acid dehydrogenases and are subdivided into three subclasses, based on coenzyme specificity: NAD+-specific, NAD+/NADP+ dual-specific, and NADP+-specific. We determined in this work that the mitochondrial AtGDH1 isozyme from A. thaliana is NAD+-specific. Altogether, A. thaliana expresses three GDH isozymes (AtGDH1-3) targeted to mitochondria, of which AtGDH2 has an extra EF-hand motif and is stimulated by calcium. Our enzymatic assays of AtGDH1 established that its sensitivity to calcium is negligible. In vivo the AtGDH1-3 enzymes form homo- and heterohexamers of varied composition. We solved the crystal structure of recombinant AtGDH1 in the apo-form and in complex with NAD+ at 2.59 and 2.03 Å resolution, respectively. We demonstrate also that both in the apo form and in 1:1 complex with NAD+, it forms D3-symmetric homohexamers. A subunit of AtGDH1 consists of domain I, which is involved in hexamer formation and substrate binding, and of domain II which binds coenzyme. Most of the subunits in our crystal structures, including those in NAD+ complex, are in open conformation, with domain II forming a large (albeit variable) angle with domain I. One of the subunits of the AtGDH1-NAD+ hexamer contains a serendipitous 2OG molecule in the active site, causing a dramatic (∼25°) closure of the domains. We provide convincing evidence that the N-terminal peptide preceding domain I is a mitochondrial targeting signal, with a predicted cleavage site for mitochondrial processing peptidase (MPP) at Leu17-Leu18 that is followed by an unexpected potassium coordination site (Ser27, Ile30). We also identified several MPD [(+/-)-2-methyl-2,4-pentanediol] binding sites with conserved sequence. Although AtGDH1 is insensitive to MPD in our assays, the observation of druggable sites opens a potential for non-competitive herbicide design.

Biofilms offer an excellent example of ecological interaction among bacteria. Temporal and spatial oscillations in biofilms are an emerging topic. In this paper, we describe the metabolic oscillations in Bacillus subtilis biofilms by applying the smallest theoretical chemical reaction system showing Hopf bifurcation proposed by Wilhelm and Heinrich in 1995. The system involves three differential equations and a single bilinear term. We specifically select parameters that are suitable for the biological scenario of biofilm oscillations. We perform computer simulations and a detailed analysis of the system including bifurcation analysis and quasi-steady-state approximation. We also discuss the feedback structure of the system and the correspondence of the simulations to biological observations. Our theoretical work suggests potential scenarios about the oscillatory behaviour of biofilms and also serves as an application of a previously described chemical oscillator to a biological system.

• Astrocyte LepR deletion reduces basal synaptic transmission in the hippocampus. • Astrocyte LepR modulate NMDA-induced LTD within the hippocampus. • Astrocyte LepR regulate the expression of the glutamate transporter GLT-1. • Astrocyte LepR are involved in glutamate uptake and neurotransmission. The aim of this study was to indentify the involvement of leptin receptors (LepR) in astrocytes in hippocampal synaptic transmission and plasticity and metabolism. To this end we used a genetic mouse model (GFAP-LepR−/−) of specific LepR ablation in GFAP positive cells and recorded excitatory postsynaptic potentials (fEPSPs) within the CA1 area. Glutamate (Glu) uptake and the expression of Glu transporters (EEAT3, GLT-1 and GLAST) and enzymes involved in Glu metabolism (glutamine synthase, GABA decarboxylase 65 and 67) were quantified. Modifications in the expression of GFAP, the glucose transporter (GLUT)-1, and the monocarboxylate transporters MCT-2 and MCT-4, were also analyzed. The results show that depletion of LepR in GFAP positive cells reduced basal synaptic transmission within the CA1 area and impaired N -methyl- d -aspartate (NMDA)-evoked long-term depression (NMDA-LTD). Hippocampal slices from GFAP-LepR−/− mice displayed lower Glu uptake efficacy together with up-regulation of GLT-1, glutamine synthase, GFAP and GLUT-1. In conclusion, astrocyte LepRs are involved in the maintenance of Glu homeostasis and Glu neurotransmission within the hippocampus. Our findings support a role of hippocampal LepRs in synaptic plasticity, which could have an impact on memory and learning processes. [ABSTRACT FROM AUTHOR]

Glutamate dehydrogenase (GDH) releases ammonia in a reversible NAD(P)+-dependent oxidative deamination of glutamate that yields 2-oxoglutarate (2OG). In current perception, GDH contributes to Glu homeostasis and plays a significant role at the junction of carbon and nitrogen assimilation pathways. GDHs are members of a superfamily of ELFV (Glu/Leu/Phe/Val) amino acid dehydrogenases and are subdivided into three subclasses, based on coenzyme specificity: NAD+-specific, NAD+/NADP+ dual-specific, and NADP+-specific. We determined in this work that the mitochondrial At GDH1 isozyme from A. thaliana is NAD+-specific. Altogether, A. thaliana expresses three GDH isozymes (At GDH1-3) targeted to mitochondria, of which At GDH2 has an extra EF-hand motif and is stimulated by calcium. Our enzymatic assays of At GDH1 established that its sensitivity to calcium is negligible. In vivo the At GDH1-3 enzymes form homo- and heterohexamers of varied composition. We solved the crystal structure of recombinant At GDH1 in the apo-form and in complex with NAD+ at 2.59 and 2.03 Å resolution, respectively. We demonstrate also that both in the apo form and in 1:1 complex with NAD+, it forms D 3-symmetric homohexamers. A subunit of At GDH1 consists of domain I, which is involved in hexamer formation and substrate binding, and of domain II which binds coenzyme. Most of the subunits in our crystal structures, including those in NAD+ complex, are in open conformation, with domain II forming a large (albeit variable) angle with domain I. One of the subunits of the At GDH1-NAD+ hexamer contains a serendipitous 2OG molecule in the active site, causing a dramatic (∼25°) closure of the domains. We provide convincing evidence that the N-terminal peptide preceding domain I is a mitochondrial targeting signal, with a predicted cleavage site for mitochondrial processing peptidase (MPP) at Leu17-Leu18 that is followed by an unexpected potassium coordination site (Ser27, Ile30). We also identified several MPD [(+/-)-2-methyl-2,4-pentanediol] binding sites with conserved sequence. Although At GDH1 is insensitive to MPD in our assays, the observation of druggable sites opens a potential for non-competitive herbicide design. [ABSTRACT FROM AUTHOR]

Background: Chemokine C–C motif ligand 2 (CCL2) is one of the most widely recognised proinflammatory chemokines in cognitive disorders. Currently, CCL2-targeting drugs are extremely limited. Thus, this study aimed to explore the neuroprotection afforded by naringin in CCL2-induced cognitive impairment in rats. Methods: Before the CCL2 intra-hippocampal injection, rats were treated with naringin for 3 consecutive days via intraperitoneal injection. Two days post-surgery, the Morris water maze (MWM) and novel object recognition (NORT) tests were performed to detect spatial learning and memory and object cognition, respectively. Nissl staining and dUTP nick-end labelling (TUNEL) staining were performed to assess histopathological changes in the hippocampus. Commercial kits were used to measure the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the content of malondialdehyde (MDA). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine the relative mRNA expression of interleukin 1β, (IL-1β), interleukin 6 (IL-6), glutamate/aspartate transporter (GLAST), glutamate transporter-1 (GLT-1), phosphate-activated glutaminase (PAG), cysteine aspartic acid-specific protease 8 (caspase-8), cysteine aspartic acid-specific protease 3 (caspase-3), cell lymphoma/leukaemia-2 (Bcl-2), and Bcl-2 associated X protein (Bax). Results: In the MWM, the average escape latency and average swimming distance were significantly reduced and the crossing times were increased in the naringin-treated groups, compared with the CCL2 group. The NORT results revealed that, compared with the CCL2 rats, the discrimination index in the naringin-treated rats increased significantly. Nissl and TUNEL staining revealed that naringin protected the structure and survival of the neurons in the CA1 zone of the hippocampus. In the naringin-treated groups, the SOD and GSH-Px activities were increased, whereas the MDA levels were decreased. Furthermore, in the naringin-treated groups, the relative mRNA expression of IL-1β and IL-6 was significantly decreased; GLAST and GLT-1 mRNA expression levels were increased, whereas PAG was decreased. In the naringin-treated groups, the relative mRNA expression levels of caspase-8, caspase-3, and Bax were decreased, whereas that of Bcl-2 was increased. Conclusion: Collectively, these data indicated that naringin alleviated the CCL2-induced cognitive impairment. The underlying mechanisms could be associated with the inhibition of neuroinflammation, oxidative stress, apoptosis, and the regulation of glutamate metabolism. [ABSTRACT FROM AUTHOR]

Abstract Background Glutamine and glutamate are known to play important roles in cancer biology. However, no detailed information is available in terms of their levels of involvement in various biological processes across different cancer types, whereas such knowledge could be critical for understanding the distinct characteristics of different cancer types. Our computational study aimed to examine the functional roles of glutamine and glutamate across different cancer types. Methods We conducted a comparative analysis of gene expression data of cancer tissues versus normal control tissues of 11 cancer types to understand glutamine and glutamate metabolisms in cancer. Specifically, we developed a linear regression model to assess differential contributions by glutamine and/or glutamate to each of seven biological processes in cancer versus control tissues. Results While our computational predictions were consistent with some of the previous observations, multiple novel predictions were made: (1) glutamine is generally not involved in purine synthesis in cancer except for breast cancer, and is similarly not involved in pyridine synthesis except for kidney cancer; (2) glutamine is generally not involved in ATP production in cancer; (3) glutamine’s contribution to nucleotide synthesis is minimal if any in cancer; (4) glutamine is not involved in asparagine synthesis in cancer except for bladder and lung cancers; and (5) glutamate does not contribute to serine synthesis except for bladder cancer. Conclusions We comprehensively predicted the roles of glutamine and glutamate metabolisms in selected metabolic pathways in cancer tissues versus control tissues, which may lead to novel approaches to therapeutic development targeted at glutamine and/or glutamate metabolism. However, our predictions need further functional validation.

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths worldwide. Early diagnosis of the disease can greatly improve the clinical prognosis for patients with CRC. Unfortunately, there are no current simple and effective early diagnostic markers available. The transfer RNA (tRNA)-derived RNA fragments (tRFs) are a class of small non-coding RNAs (sncRNAs), which have been shown to play an important role in the development and prognosis of CRC. However, only a few studies on tRFs as early diagnostic markers in CRC have been conducted. In this study, previously ignored tRFs expression data were extracted from six paired small RNA sequencing data in the Sequence Read Archive (SRA) database using MINTmap. Three i-tRFs, derived from the tRNA that transports glutamate (i-tRF-Glu), were identified and used to construct a random forest diagnostic model. The model performance was evaluated using the receiver operating characteristic (ROC) curve and precision-recall (PR) curve. The area under the curves (AUC) for the ROC and PR was 0.941 and 0.944, respectively. We further verified the differences in expression of the these i-tRF-Glu in the tissue and plasma of both CRC patients and healthy subjects using quantitative real-time PCR (qRT-PCR). We found that the ROC-AUC of the three was greater than traditional plasma tumor markers such as CEA and CA199. Our bioinformatics analysis suggested that the these i-tRF-Glu are associated with cancer development and glutamate (Glu)-glutamine (Gln) metabolism. Overall, our study uncovered these i-tRF-Glu that have early diagnostic significance and therapeutic potential for CRC, this warrants further investigation into the diagnostic and therapeutic potential of these i-tRF-Glu in CRC., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

• An underivatized LC–MS/MS method for simultaneous determination of several neurotransmitters of Trp, Phe and Glu metabolism was developed. • The method was independently verified in urine, plasma and hippocampus according to FDA guideline for bioanalytical method validation. • The method was applied to determine the concentrations of the neurotransmitters in CUMS-induced depression rats' hippocampus, plasma and urine. • Tyr, Trp, 5-HT and QUIN levels were significantly altered in CNS and peripheral matrices. • The peripheral transformation of neurotransmitters may be directly or indirectly involved in pathological processes. Sensitive and comprehensive measurement of systemic metabolites of tryptophan, phenylalanine and glutamate metabolism in biological samples is effective for understanding the pathogenesis of depression and other neurological diseases. Therefore, this study developed an underivatized liquid chromatography tandem mass spectrometry (LC–MS/MS) method for simultaneous monitoring the 3 components of glutamate metabolism in rat hippocampus and 11 components of tryptophan and phenylalanine metabolism in rat hippocampus, plasma and urine, and applied it to investigate their changes in rats induced by chronic unpredictable mild stress (CUMS). The investigated analytes are as follows: tryptophan, serotonin, 5-hydroxyindoleacetic acid, kynurenine, kynurenic acid, xanthurenic acid, 3-hydroxyanthranilic acid, quinolinic acid, phenylalanine, tyrosine, tyramine, glutamate, glutamine and gamma-aminobutyric acid. The method was verified to be sensitive and effective with satisfactory linearity, accuracies in the range of 78.2%–120.4%, and precisions less than 17.8% for all identified analytes. A series of significant changes in CUMS-induced rats can be detected: tryptophan, serotonin and tyrosine levels decreased and quinolinic acid increased in both hippocampus and plasma. In addition, the kynurenine/tryptophan ratios increased in hippocampus and plasma, the kynurenic acid/quinolinic acid ratios of plasma and urine were significantly reduced. These findings demonstrated that the CUMS procedure could lead to the central and peripheral imbalances of tryptophan and phenylalanine metabolism. In conclusion, a LC–MS/MS method for simultaneous measurement of several neurotransmitters in rat hippocampus, plasma and urine was developed and successfully applied to investigation of the central and peripheral changes in CUMS-induced rats. The method would be expected to provide applicability to the study of the mechanisms of depression and other related diseases associated with these neurotransmitters. [ABSTRACT FROM AUTHOR]

Exposure to fluoride (F) during the development affects central nervous system of the offspring rats which results in the impairment of cognitive functions. However, the exact mechanisms of F neurotoxicity are not clearly defined. To investigate the effects of perinatal F exposure on memory ability of young rat offspring, dams were exposed to 5 and 10 mg/L F during gestation and lactation. Additionally, we evaluated the possible underlying neurotoxic mechanisms implicated. The results showed that the memory ability declined in 45-day-old offspring, together with a decrease of catalase and glutamate transaminases activity in specific brain areas. The present study reveals that exposure to F in early stages of rat development leads to impairment of memory in young offspring, highlighting the alterations of oxidative stress markers as well as the activity of enzymes involved in the glutamatergic system as a possible mechanisms of neurotoxicity. [ABSTRACT FROM AUTHOR]

Abstract The excitatory amino acid transporter type 2 (EAAT2) represents the major mechanism for removal of extracellular glutamate. In the hippocampus, there is some EAAT2 in axon-terminals, whereas most of the protein is found in astroglia. The functional importance of the neuronal EAAT2 is unknown, and it is debated whether EAAT2-expressing nerve terminals are present in other parts of the brain. Here we selectively deleted the EAAT2 gene in neurons (by crossing EAAT2-flox mice with synapsin 1-Cre mice in the C57B6 background). To reduce interference from astroglial EAAT2, we measured glutamate accumulation in crude tissue homogenates. EAAT2 proteins levels were measured by immunoblotting. Although synapsin 1-Cre mediated gene deletion only reduced the forebrain tissue content of EAAT2 protein to 95.5 ± 3.4% of wild-type (littermate) controls, the glutamate accumulation in homogenates of neocortex, hippocampus, striatum and thalamus were nevertheless diminished to, respectively, 54 ± 4, 46 ± 3, 46 ± 2 and 65 ± 7% of controls (average ± SEM, n = 3 pairs of littermates). GABA uptake was unaffected. After injection of U-13C-glucose, lack of neuronal EAAT2 resulted in higher 13C-labeling of glutamine and GABA in the hippocampus suggesting that neuronal EAAT2 is partly short-circuiting the glutamate-glutamine cycle in wild-type mice. Crossing synapsin 1-Cre mice with Ai9 reporter mice revealed that Cre-mediated excision occurred efficiently in hippocampus CA3, but less efficiently in other regions and hardly at all in the cerebellum. Conclusions: (1) EAAT2 is expressed in nerve terminals in multiple brain regions. (2) The uptake catalyzed by neuronal EAAT2 plays a role in glutamate metabolism, at least in the hippocampus. (3) Synapsin 1-Cre does not delete floxed genes in all neurons, and the contribution of neuronal EAAT2 is therefore likely to be larger than revealed in the present study. Highlights • Nerve terminals expressing EAAT2 are widely distributed in the brain and are not limited to the hippocampus. • Deletion of neuronal EAAT2 leads re-routing of extracellular glutamate. • Synapsin 1-Cre mice is not active in all neurons raising the question if there are more neuronal EAAT2 than detected here. [ABSTRACT FROM AUTHOR]

Competition for water between agricultural and non-agricultural economic sectors hampers agricultural production, especially in water-scarce regions. Understanding crop responses in terms of yield and quality to irrigation is an important factor in designing appropriate irrigation management for optimal crop production and quality. Pelargonium sidoides DC., often harvested from the wild, is in high demand in the informal market and for commercial formulations. Agricultural production of high-quality materials through cultivation can help reduce pressure on its wild populations. This study aimed at determining the effects of water and nitrogen on P. sidoides yield and metabolite production. The irrigation treatments applied were 30%, 50%, and 70% of an allowable depletion level (ADL), while the nitrogen (N) levels were 0 (control), 50, 100, and 150 kg ha−1. The 30% ADL resulted in a significantly higher biomass and root yield. Nitrogen at 50 and 100 kg ha−1 resulted in a significantly higher biomass yield, compared to the N control. An increase in sugars and citrate cycle components was observed for the well-watered 30% ADL treatment, whereas water-stressed (50% and 70% ADL) treatments increased alanine, aspartate, and glutamate metabolism, increasing levels of asparagine, 4-aminobutyrate, and arginine. The treatments had no significant effect on the root content of esculin, scopoletin, and umckalin. Water stress induced metabolite synthesis to mitigate the stress condition, whereas under no water stress primary metabolites were synthesized. Moreover, cultivation of P. sidoides as a conservation strategy can increase yield without affecting its bioactivity, while providing sustenance for the rural communities.