Search Results (245)

CD19-chimeric antigen receptor (CAR) has shown promising outcomes in B-cell malignancies. However, relapses due to poor CAR-T persistence and antigen escape have occurred. CD37 is a potential alternative immunotherapy for CD19⁻ tumors. Inferior CAR-T cytotoxicity was observed in CD37CAR-T compared to CD19CAR-T model that was possibly due to lower CD37CAR affinity. To alleviate CD37CAR functions, we optimized the most prevalent linkers, Whitlow (18aaL) and glycine–serine (GS4L). CD37.GS4L CAR-T showed higher transduction efficiency and T-cell expansion contributed by minimizing T-cell fratricide. In chronic antigen stimulation, CD37.GS4L CAR demonstrated robust T-cell proliferation while preserving stemness and a decrease in induced exhaustion phenotype, which resulted in greater tumoricidal activity among various CD37⁺ malignancies. In silico analysis showed that CD37.GS4L scFv altered structural dynamic behaviors by facilitating variable heavy-chain region closer to CD37 receptor with higher binding affinity and less aggregation of negatively charged protein, which contributed to lower tonic signaling during CAR activation and diminished exhaustion. Ultimately, effective anti-tumor control with notable memory T-cell persistence was exhibited in Burkitt lymphoma mice treated with CD37.GS4L CAR-T. Additionally, CD37.GS4L CAR-T illustrated the potential in vivo cytotoxicity in myeloma-inoculated mice. In summary, the flexibility and affinity of glycine–serine linker of CD37CAR can potentiate CAR-T functionality. Full article

Amino acids are essential nutrients for both tumor growth and immune cell function. Cancer cells actively deplete intracellular and extracellular amino acid pools, and limited amino acid availability in the tumor microenvironment (TME) reinforces immunosuppression. Mitochondria are not merely adenosine triphosphate-producing organelles. Amino acid metabolism within mitochondria contributes to tumor progression and influences immune cell fate and effector function. These effects are mediated through biosynthetic precursor generation for lipid, nucleotide, and polyamine synthesis, maintenance redox homeostasis through glutathione and NAD⁺ metabolism, and regulation of gene expression through aryl hydrocarbon receptor signaling. In this review, we discuss four major mitochondrial amino acid metabolic pathways: glutamine-driven anaplerosis, serine/glycine-dependent one-carbon metabolism, arginine–ornithine metabolism, and tryptophan–kynurenine metabolism. We examine how these pathways are rewired in cancer cells, how they influence immune cell function through direct or mitochondria-associated mechanisms, and how such metabolic reprogramming promotes tumor progression while impairing antitumor immunity. Finally, we consider therapeutic strategies to improve cancer immunotherapy by targeting amino acid metabolism, including mitochondrial metabolic enzymes. This review may help guide the development of more effective metabolic biomarkers and mitochondria-based therapeutic strategies for cancer immunotherapy. Full article

Flavonoids exert antioxidant activity by scavenging free radicals, chelating metals, and modulating antioxidant enzymes. The root extract of Glycine tomentella Hayata (GTE), a traditional Chinese medicinal herb contains flavonoids, particularly, isoflavones. However, its neuroprotective effects against anxiety remain unclear. In this study, the effects of GTE on anxiety-like behavior and oxidative stress in male Balb/c mice were investigated. The mice were administered GTE orally once daily for 14 d and subsequently, the anxiolytic-like effects of the extract were observed via elevated plus maze and open field tests. Oxidative stress levels in the treated mice were also measured. The results obtained identified daidzein (9.19 mg/g dry extract) and daidzin (2.95 mg/g dry extract) as the key isoflavones in GTE. Furthermore, free radical scavenging assays confirmed that GTE shows strong antioxidant activity, with an IC50 value of 8.82 μg/mL. It also showed pronounced anxiolytic effects, attenuating reactive oxygen species production in a dose-dependent manner. Mechanistic studies attributed these effects to the estrogenic activity of daidzein, which possibly modulates emotional state via estrogen receptor activation and systemic oxidative stress mitigation. These findings suggest that isoflavone-enriched GTE is a natural resource with potential for use as an antioxidant for mitigating anxiety. Full article

Neuronal synapses are the functional units of communication in the central nervous system. This review describes the molecular mechanisms regulating synaptic transmission, plasticity, and circuit refinement. At the presynaptic active zone, scaffolding proteins including bassoon, piccolo, RIMs, and munc13 organize vesicle priming and the localization of voltage-gated calcium channels. Neurotransmitter release is mediated by the SNARE complex, comprising syntaxin-1, SNAP25, and synaptobrevin, and triggered by the calcium sensor synaptotagmin-1. Following exocytosis, synaptic vesicles are recovered through clathrin-mediated, ultrafast, bulk, or kiss-and-run endocytic pathways. Postsynaptically, the postsynaptic density (PSD) serves as a protein hub where scaffolds such as PSD-95, shank, homer, and gephyrin anchor excitatory (AMPA, NMDA) and inhibitory (GABA-A, Glycine) receptors are observed. Synaptic strength is modified during long-term potentiation (LTP) and depression (LTD) through signaling cascades involving kinases like CaMKII, PKA, and PKC, or phosphatases such as PP1 and calcineurin. These pathways regulate receptor trafficking, Arc-mediated endocytosis, and actin-dependent remodeling of dendritic spines. Additionally, synapse formation and elimination are guided by cell adhesion molecules, including neurexins and neuroligins, and by microglial pruning via the complement cascade (C1q, C3) and “don’t eat me” signals like CD47. Molecular diversity is further expanded by alternative splicing and post-translational modifications. A unified model of synaptic homeostasis is required to understand the basis of neuropsychiatric and neurological disorders. Full article

Background/Objectives: The neurotransmitter glycine is involved in several physiological and pathological conditions in the Central Nervous System. Different biological structures, including glycine receptors and transporters, are under study as targets for potential drugs acting against serious neurological and psychiatric disorders. The regulation of glycine release from nerve terminals is only partially understood. We report here preliminary evidence of the modulation of glycine release through presynaptic metabotropic glutamate receptors 1 (mGlu1) from glycinergic nerve terminals in mouse hippocampi. Methods: Purified mouse hippocampal synaptosomes labeled with [³H]glycine were used to study glycine release under superfusion conditions. Results: The group I metabotropic glutamate receptor agonist 3,5-DHPG potentiated depolarization-evoked [³H]glycine release from hippocampal synaptosomes, an effect strongly counteracted by the selective mGlu1 antagonist LY 367385. 3,5-DHPG failed to increase [³H]glycine release in Grm1^crv4/crv4 mice, a mouse model lacking mGlu1. Although further research is needed to clarify these mechanisms, data suggest that glycine-releasing hippocampal nerve terminals are endowed with presynaptic mGlu1 receptors whose activation potentiates glycine release. Conclusions: Considering that in the hippocampus, glycine is relevant as a co-agonist of glutamate at NMDA receptors and that mGlu1 receptor ligands are under study as potential drugs, we propose that the possible effects of these agents on the release of glycine should be considered when studying these compounds. Full article

Ovarian cancer stem cells (OCSCs) possess stemness; differentiation capacity; and tolerance to oxidative, metabolic, and therapeutic stress, driving recurrence and chemoresistance. Emerging evidence highlights a synergistic interplay between redox homeostasis and amino acid metabolism in maintaining stemness and treatment resistance. This review integrates redox regulation, amino acid metabolic reprogramming, and tumor microenvironment (TME) signals into a unified “redox–amino acid–TME” framework. OCSCs balance signal transduction and antioxidant defense by fine-tuning reactive oxygen species (ROS) levels. Glutamine, serine/glycine, and sulfur amino acid metabolism collectively generate NADPH and glutathione, sustaining the GPX4/TRX antioxidant systems and suppressing ferroptosis. Branched-chain amino acid (BCAA)–mTOR and tryptophan (Trp)–aryl hydrocarbon receptor (AhR) axes couple amino acid sensing to redox signaling, stabilizing the stem-like phenotype. Under TME stress, including hypoxia, acidity, and nutrient competition, exosomes and stromal components reinforce stemness and immune evasion through metabolic and redox crosstalk. Therapeutically, targeting glutamine metabolism (ASCT2/GLS), serine biosynthesis (PHGDH/SHMT), or antioxidant defenses (xCT/GPX4) disrupts reducing power, increases oxidative stress, and enhances the efficacy of chemotherapy, PARP inhibition, and immunotherapy. Biomarkers such as xCT/GPX4 expression, PHGDH levels, Nrf2 activity, and GSH/NADPH ratios may guide patient stratification and response prediction. Overall, understanding the redox–amino acid metabolic network provides a mechanistic basis and translational opportunities for precision metabolic therapies in ovarian cancer. Full article

Skin aging is primarily driven by oxidative stress, mitochondrial dysfunction, and cell cycle dysregulation. This study investigated the anti-senescence effects of fermented porcine placenta (FPP) and its dipeptides, leucine–glycine (LG) and proline–hydroxyproline (PH), in human epidermal keratinocytes (HEKs), using nicotinamide mononucleotide (NMN) as a reference for nicotinamide adenine dinucleotide (NAD⁺)-related pathways. FPP suppressed senescence-associated β-galactosidase (SA-β-gal) activity and Cyclin-dependent kinase inhibitor 2A (p16) expression while enhancing adenosine triphosphate (ATP) production and sirtuin 1 (SIRT1)–peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) signaling. LG and PH exhibited distinct actions: LG improved redox balance by increasing the NAD⁺/NADH ratio and NAD(P)H quinone oxidoreductase 1 (NQO1) activity, whereas PH modulated cell cycle regulators and upregulated sirtuin 3 (SIRT3) expression. Although both peptides contributed to FPP’s effects, their combination did not fully replicate its overall activity, suggesting synergistic roles of multiple bioactive constituents. These findings highlight FPP as a multifactorial modulator of keratinocyte senescence, acting via mitochondrial and redox-related mechanisms. Full article

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) reprograms central carbon metabolism by switching pyruvate kinase expression from isoform M1 (Pkm1) to M2 (Pkm2), mediated by aryl hydrocarbon receptor (AhR) binding to a dioxin response element (DRE) located between exons 3 and 4 within the Pkm locus. To further investigate the consequences of Pkm isoform switching in TCDD elicited hepatotoxicity, we examined gene expression in primary hepatocytes isolated from mice with the Pkm locus DRE excised (Pkm^ΔDRE). Wild-type and Pkm^ΔDRE hepatocytes were treated with 10 nM TCDD for 2, 4, 8, 12, 24, 48, 72, 96 and 120 h. Central carbon metabolite changes were also assessed in WT and Pkm^ΔDRE mice treated with 30 µg/kg TCDD every 4 day for 28 days. While AHR target genes were comparably induced, some genes exhibited divergent expression patterns in Pkm^ΔDRE mice compared to wild-types following treatment with TCDD. Notably, antioxidant gene expression was delayed in Pkm^ΔDRE hepatocytes. Metabolomic analysis also revealed differences in glycolytic, TCA cycle and pentose phosphate pathway metabolite levels in TCDD-treated WT and Pkm^ΔDRE liver extracts. In addition, amino acid metabolism and serine/glycine synthesis were also elevated, especially in Pkm^ΔDRE. These findings indicate PKM2 induction affects the transcriptional and metabolic coordination of hepatic responses to TCDD. Full article

The current pharmacological approach for the treatment of opioid use disorder (OUD), as a result of prescription misuse or illicit opioids, utilises opioid ligands that have either an agonist or antagonist profile. In this context, methadone and buprenorphine act as opioid agonists, whereas naltrexone functions as an opioid antagonist. To decrease the reinforcing effects of illicit opioids, higher doses of methadone and buprenorphine have been recommended, but this is associated with increased side effects. Therefore, several preclinical efforts have been carried out over the last decades to find drugs that act on receptors other than opioid receptors. A large body of preclinical evidence has shown the ability of N-methyl-D-aspartate receptor (NMDAR) antagonists like ketamine to treat opioid addiction behaviours in animals. Indeed, ketamine by itself is an addictive drug; thus, the treatment of OUD is still a matter to be solved. Growing data position glycine transporter 1 as a possible therapeutic target for the treatment of substance use disorder. This transporter regulates the reuptake of glycine, which can modulate the function of both NMDARs and GPR158, a metabotropic glycine receptor (mGlyR); thus, it is worth investigating in the management of OUD. To gain insight into the role of glycinergic transmission in OUD, alongside NMDAR-mediated glutamatergic transmission, dopaminergic and GABAergic transmission were also reviewed. Full article

Glycine receptors (GlyRs) are essential for inhibitory neurotransmission in the central nervous system (CNS) and represent promising targets against neurological disorders. Several indole alkaloids from Gelsemium species have been shown to modulate GlyRs. Notably, the anxiolytic and analgesic properties of certain Gelsemium alkaloids appear to depend on GlyR modulation. However, prior studies have focused on only a few indole alkaloids, leaving the activity of other Gelsemium compound classes unexplored. This study employed an integrative in silico approach to investigate the interactions between GlyR α1 and α3 subtypes and 162 structurally diverse Gelsemium compounds. Physicochemical, pharmacokinetic, and toxicological analyses identified compounds with favorable bioavailability in the CNS. Molecular docking revealed that indolic alkaloids bind the GlyR orthosteric site with profiles comparable to the reference Gelsemium compound, gelsemine. Molecular dynamics simulations confirmed the stability and conformational integrity of selected ligand-receptor complexes. Overall, novel potential GlyR modulators were identified, with several compounds showing a promising selectivity profile towards GlyR α1 and α3 subtypes. These findings further support the therapeutic potential of Gelsemium alkaloids and provide a foundation for further pharmacological and toxicological validation. Full article

Background/Objectives: Stroke is the second leading cause of death worldwide. There is an unmet need to manage stroke pathophysiology, including L-glutamate (L-Glu)-mediated neurotoxicity. The acai berry (Euterpe sp.) contains phytochemicals with potentially nutraceutical content. The aim of this study was to assess the ability of acai berry extracts to counter L-Glu neurotoxicity using human differentiated TE671 cells. Methods: The cytotoxicity of L-Glu and acai berry extracts was quantified using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Mitochondrial function was examined by a quantitation of cellular ATP levels, the maintenance of the mitochondrial membrane potential (MMP), and the production of reactive oxygen species (ROS). Whole-cell patch-clamp recordings monitored the activation of N-methyl-D-aspartate receptors (NMDARs). Candidate phytochemicals from acai berry extracts were modeled in silico for NMDAR binding. Results: L-Glu significantly reduced cell viability, ATP levels, the MMP, and increased cellular ROS. Generally, acai berry extracts alone were not cytotoxic, although high concentrations were detrimental to ATP production, maintenance of the MMP, and elevated ROS levels. Whole-cell patch-clamp recordings revealed that the combined addition of 300 µM L-Glu and 10 µM glycine activated currents in differentiated TE671 cells, consistent with triggering NMDAR activity. Acai berry extracts ameliorated the L-Glu-induced cytotoxicity, mitochondrial dysfunction, elevated ROS levels, and limited the NMDAR-mediated excitotoxicity (p < 0.001–0.0001). Several virtual ligands from acai berry extracts exhibited high-affinity NMDAR binding (arginine, 2,5-dihydroxybenzoic acid, threonine, protocatechuic acid, and histidine) as possible candidate receptor antagonists. Conclusions: Acai berry phytochemicals could be exploited to reduce the L-Glu-induced neurotoxicity often observed in stroke and other neurodegenerative diseases. Full article

The proposed physiological roles of bile acids have expanded beyond the digestion of fats to encompass cell signaling via the activation of a variety of nuclear and plasma membrane receptors in multiple organ systems. The current in silico study was inspired by previous observations from our group and others that bile acids interact functionally with cardiac, pulmonary, and gastrointestinal muscarinic receptors and more recent work demonstrating allosteric binding of cholesterol, the parent molecule for bile acid synthesis, to M₁ muscarinic receptors (M₁R). Here, we computationally tested the hypothesis that bile acids can allosterically bind to M₁R and thereby modulate receptor activation. Utilizing de novo site identification by the ligand competitive saturation (SILCS) method, putative novel allosteric binding sites of bile acid targeting M₁R were identified. Molecular dynamics simulations were used to uncover the molecular details of the activation mechanism of M₁R due to agonist binding along with allosteric modulation of bile acids on M₁R activation. Allosteric binding of bile acids and their glycine and taurine conjugates to M₁R negatively impacts the activation process, findings consistent with recent reports that M₁R expression and activation inhibit colon cancer cell proliferation. Thus, bile acids may augment colon cancer risk by inhibiting the tumor suppressor actions of M₁R. When validated experimentally, these findings are anticipated to shed light on our understanding of how bile acids in the membrane microenvironment can allosterically modulate the function of M₁R and possibly other G protein-coupled receptors. Full article

Most amino acids contain a chiral center and thus, can exist as L- and D-isomers. For many years, it was thought that only the L-isomers were present in mammals. However, in recent decades it has been demonstrated that D-isomers are also present. Three of these amino acids, namely D-serine, D-aspartate, and D-alanine, have been proposed to play a role in the etiology of schizophrenia via interactions with glutamate receptors. D-Serine and D-alanine act at the glycine modulatory site on the NMDA receptor, while D-aspartate acts at the glutamate site on the same receptor. D-aspartate also acts on the mGlu5 receptor and can stimulate glutamate release presynaptically. Preclinical studies have reported that manipulations to reduce brain levels of D-serine, D-aspartate, or D-alanine lead to schizophrenia-relevant behaviors, and clinical studies have reported reduced levels of these D-amino acids in the brain tissue (postmortem) and/or body fluids from schizophrenia patients compared to those noted in controls, although there are some contradictory findings. The possible use of these amino acids and/or the manipulation of their relevant enzymes in the treatment of schizophrenia are described. D-Cysteine has been identified recently in human brain tissue, with the highest values in white matter; demonstration of its involvement in brain development has led to speculation that it could be involved in the etiology of schizophrenia, identifying it as a potential therapy in combination with antipsychotics. Future directions and potential problems that should be considered in studies on D-amino acids and their relevant enzymes in schizophrenia are discussed. Full article

Activated protein C (APC) exerts anticoagulant and cytoprotective cell signaling activities. APC’s cell signaling requires protease-activated receptor (PAR) PAR1 and PAR3, and APC’s PAR cleavages generate peptides capable of agonizing biased G-protein coupled receptor (GPCR) cytoprotective signaling, resulting in anti-inflammatory and anti-apoptotic activities and endothelial barrier stabilization. The PAR-sequence-derived 34-residue “G10 peptide” comprising PAR1 residues 47–55 covalently attached by a 10-glycine linker to PAR3 residues 51–65 is an orthosteric/allosteric bivalent GPCR agonist that potently mimics APC’s anti-inflammatory activity and endothelial barrier stabilization activity. The objective of this study was to determine whether the G10 peptide mimics APC’s anti-apoptotic activity using cultured murine neurons challenged by N-methyl-d-aspartate that provokes neuronal apoptosis. In these new studies, the G10 peptide mimicked APC’s anti-apoptotic activity. Thus, the PAR-derived 34-residue G10 peptide mimics APC’s three major cytoprotective activities, namely anti-inflammatory and anti-apoptotic activities and endothelial barrier stabilization. Peptides that agonize GPCRs provide promising and currently approved drugs; e.g., semaglutide and tirzepatide that contain 31 and 39 amino acid residues, respectively. Thus, this new study adds to the rationale for pursuing further studies of the G10 peptide for potential therapeutic value for multiple pathologies where APC or signaling-selective APC variants are therapeutic in preclinical animal studies. Full article

Glioblastoma multiforme (GBM) remains one of the most aggressive and treatment-resistant brain tumors, with poor prognosis and limited therapeutic options. Background/Objectives: Integrin α_vβ₃, a cell surface receptor overexpressed in GBM, specifically binds to cyclic arginine-glycine-aspartate-D-phenylalanine-lysine (c(RGDfK)) motif, making it a valuable target for tumor-specific delivery and PET imaging. This study explores a novel radiotheranostic agent, [⁶⁴Cu]Cu-NOTA-TP-c(RGDfK), which combines the imaging and therapeutic capabilities of copper-64 (⁶⁴Cu) and the cytotoxic activity of a terpyridine-platinum (TP) complex, conjugated to c(RGDfK). Methods: A robust protocol was developed for the small-scale preparation of NOTA-TP-c(RGDfK). Comparative cellular studies were conducted using U87 MG glioblastoma (GBM) cells and SVG p12 human astrocytes to evaluate the performance of [⁶⁴Cu]Cu-NOTA-TP-c(RGDfK) relative to [⁶⁴Cu]Cu-NOTA-c(RGDfK), [⁶⁴Cu]Cu-NOTA-TP, ^natCu-NOTA-TP-c(RGDfK), cisplatin, and temozolomide. Results: ⁶⁴Cu-radiolabeling of NOTA-TP-c(RGDfK) was achieved with >99% radiochemical purity, and competition assays confirmed high binding affinity to integrin α_vβ₃ (IC₅₀ = 16 ± 8 nM). Cellular uptake, internalization, and retention studies demonstrated significantly higher accumulation of [⁶⁴Cu]Cu-NOTA-TP-c(RGDfK) in U87 MG cells compared to control compounds, with 38.8 ± 1.8% uptake and 28.0 ± 1.0% internalization at 24 h. Nuclear localization (6.0 ± 0.5%) and stable intracellular retention further support its therapeutic potential for inducing localized DNA damage. Importantly, [⁶⁴Cu]Cu-NOTA-TP-c(RGDfK) exhibited the highest cytotoxicity in U87 MG cells (IC₅₀ = 10 ± 2 nM at 48 h), while maintaining minimal toxicity in normal SVG p12 astrocytes. Conclusions: These results highlight [⁶⁴Cu]Cu-NOTA-TP-c(RGDfK) as a promising targeted radiotheranostic agent for GBM, warranting further preclinical development Full article