Search Results (125)

Angelman syndrome (AS) is a neurodevelopmental disorder caused by the loss of maternal UBE3A expression, leading to disrupted proteostasis and synaptic dysfunction. Adenosine is a ubiquitous neuromodulator whose G protein-coupled receptors (ARs) regulate neuronal differentiation and neurite outgrowth during development. Here, we investigated AR signaling and their influence on survival–autophagy balance and neuronal morphology in an AS cellular model. Using SH-SY5Y cells with silenced UBE3A, we found that UBE3A loss markedly decreased A1AR, A2BAR, and A3AR protein levels while significantly increasing A2AR expression. Ligand affinity was preserved across genotypes, but A1AR and A2AAR desensitization kinetics were significantly slower in UBE3A-deficient cells. These effects were associated with reduced recruitment of G protein-coupled receptor kinase 2 (GRK2) to the plasma membrane and decreased GRK2–AR association in UBE3A-deficient cells, suggesting a possible contribution of altered GRK2 dynamics to prolonged AR signaling. Functionally, A1AR and A2AR agonists preferentially promoted survival of UBE3A-deficient cells and modulated the MDM2–p53 axis and autophagy markers; A1R stimulation also increased neurite density in UBE3A-deficient cells. Together, these results identify AR-level alterations and defective desensitization machinery in AS neuronal cells and link receptor changes to downstream proteostasis and morphological phenotypes relevant to AS pathophysiology. Full article

The safe and precise regulation of therapeutic gene expression remains a major challenge for mammalian synthetic biology and cell-based therapies. Many existing inducible systems rely on non-mammalian regulatory components or ligands with limited clinical compatibility. Designer receptors exclusively activated by designer drugs (DREADDs) offer a human G protein-coupled receptor (GPCR)-based framework for pharmacological control of intracellular signaling, yet their application as clinically relevant gene-regulation platforms remains underexplored. Here, we report a clozapine-responsive gene switch that couples a designer GPCR to signaling-dependent transcriptional control. By linking clozapine-activated receptors to cyclic adenosine monophosphate (cAMP)- or calcium-responsive synthetic promoters, receptor activation is converted into robust transgene expression across a broad dynamic range, with sensitivity to sub-nanomolar to low-nanomolar clozapine concentrations. In vivo, alginate-encapsulated reporter cells implanted in C57BL/6J mice responded to systemic or local clozapine administration with efficient secretion of a reporter protein, achieving robust induction at low daily doses (0.3 mg/kg) following either oral administration or local delivery. Together, these results establish a human GPCR-based clozapine-responsive gene switch that integrates regulation by a clinically used small molecule with modular transcriptional outputs, providing an additional approach for pharmacologically controllable gene expression in mammalian cells and in vivo. Full article

Lung cancer remains the leading cause of cancer-related mortality worldwide, with non-small cell lung cancer accounting for the majority of cases and exhibiting persistent challenges related to therapy resistance and metastatic progression. Increasing evidence indicates that dysregulated G protein-coupled receptor signaling and ion channel activity function cooperatively as master regulators of tumor cell proliferation, migration, survival, and therapeutic response. Cannabinoids, including phytocannabinoids such as delta-9-tetrahydrocannabinol and cannabidiol, as well as endogenous endocannabinoids, are uniquely positioned to modulate both G protein-coupled receptors and ion channels, thereby influencing key oncogenic signaling networks. This review synthesizes current knowledge on the role of major ion channel families, including transient receptor potential channels, potassium channels, and sodium channels, and principal G protein-coupled receptor pathways involved in lung cancer progression. We further discuss how cannabinoids reprogram these interconnected signaling systems through canonical cannabinoid receptors, non-classical targets such as G protein-coupled receptor 55 and adenosine receptors, and direct modulation of ion channel activity. Special attention is given to G protein-coupled receptor–ion channel coupling within membrane microdomains and to the capacity of cannabinoids to act as biased ligands, redirecting downstream pathways, such as the phosphoinositide 3-kinase–protein kinase B–mechanistic target of rapamycin and epidermal growth factor receptor signaling, toward apoptosis and reduced metastatic potential. Emerging strategies, including cannabinoid-based combination therapies, selective receptor biasing, and targeted delivery systems, are also highlighted. Altogether, cannabinoid-driven rewiring of G protein-coupled receptor and ion channel signaling represents a promising mechanistic framework for developing innovative therapeutic approaches against lung cancer. Full article

Chronic alcohol exposure disrupts blood–brain barrier (BBB) integrity and promotes neuroinflammation, with P2X7 receptor (P2X7R) signaling playing a critical role. Our prior work in male mice linked P2X7R inhibition to reduced extracellular adenosine triphosphate (eATP) release, modulated extracellular vesicle (EV) cargo, and attenuated neuroinflammation in chronic intermittent ethanol (CIE)-exposed mice. However, sex-specific roles of P2X7R signaling and EV-mediated mechanisms in alcohol-induced neuroinflammation remain unclear. Male and female mice were exposed to ethanol vapor for three weeks and treated with Brilliant Blue G (BBG), a P2X7R inhibitor. Compared to their respective CIE-unexposed controls, brain gene expression of tumor necrosis factor–α (Tnf-α), interleukin-1 beta (Il-1b), interleukin-6 (Il-6), monocyte chemoattractant protein-1 (Mcp-1), and Fas ligand (Fasl) significantly increased in CIE-exposed males, while only Il-1b increased in females. P2X7R inhibition significantly reduced these cytokines. Pericyte immunostaining was decreased by CIE (indicating BBB injury) in male mice only and was restored by P2X7R inhibition with no difference between groups in females. Occludin staining (another BBB marker) did not differ between the treatment groups in male and female animals. Circulating cytokines (Macrophage inflammatory protein-1 alpha (MIP-1α), tumor necrosis factor–α (TNF-α), interleukin-1 beta (IL-1β), and interleukin-27 subunit p28/interleukin-30 (IL-27p28/IL-30) were significantly elevated in CIE-exposed males but not in females, with BBG treatment reducing cytokines in males. Circulating eATP, P2X7Rs, P-glycoprotein (P-gp), EVs, and EV-mtDNA, which we identified in our previous study, were increased in both sexes and partially decreased by P2X7R blockade. Spatial memory was impaired by CIE exposure in males but not females, and this deficit was reversed by BBG treatment. Our findings reveal sex differences in CIE-induced circulating cytokines, neuroinflammation, and memory impairment, with a stronger response in males. However, other markers of cell injury associated with CIE exposure were upregulated in both sexes; P2X7R inhibition effectively mitigated these effects, highlighting the functional relevance of targeting the P2X7R in alcohol-induced injury. Full article

Astrocytes and microglia constitute nearly half of all central nervous system cells and are indispensable for its proper function. Both exhibit striking morphological and functional heterogeneity, adopting either neuroprotective (A2, M2) or proinflammatory (A1, M1) phenotypes in response to cytokines, pathogen-associated molecular patterns (PAMPs)/damage-associated molecular patterns (DAMPs), toll-like receptor 4 (TLR4) activation, and NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signaling. Crucially, many of these phenotypic transitions arise during the earliest stages of neurodegeneration, when glial dysfunction precedes overt neuronal loss and may act as a primary driver of disease onset. This review critically examines glial-centered hypotheses of neurodegeneration, with emphasis on their roles in early disease phases: (i) microglial polarization from an M2 neuroprotective state to an M1 proinflammatory state; (ii) NLRP3 inflammasome assembly via P2X purinergic receptor 7 (P2X7R)-mediated K⁺ efflux; (iii) a self-amplifying astrocyte–microglia–neuron inflammatory feedback loop; (iv) impaired microglial phagocytosis and extracellular-vesicle–mediated propagation of β-amyloid (Aβ) and tau; (v) astrocytic scar formation driven by aquaporin-4 (AQP4), matrix metalloproteinase-9 (MMP-9), glial fibrillary acidic protein (GFAP)/vimentin, connexins, and janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling; (vi) cellular reprogramming of astrocytes and NG2 glia into functional neurons; and (vii) mitochondrial dysfunction in glia, including Dynamin-related protein 1/Mitochondrial fission protein 1 (Drp1/Fis1) fission imbalance and dysregulation of the sirtuin 1/peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Sirt1/PGC-1α) axis. Promising therapeutic strategies target pattern-recognition receptors (TLR4, NLRP3/caspase-1), cytokine modulators (interleukin-4 (IL-4), interleukin-10 (IL-10)), signaling cascades (JAK2–STAT, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), phosphoinositide 3-kinase–protein kinase B (PI3K–AKT), adenosine monophosphate-activated protein kinase (AMPK)), microglial receptors (triggering receptor expressed on myeloid cells 2 (TREM2)/spleen tyrosine kinase (SYK)/ DNAX-activating protein 10 (DAP10), siglec-3 (CD33), chemokine C-X3-C motif ligand 1/ CX3C motif chemokine receptor 1 (CX3CL1/CX3CR1), Cluster of Differentiation 200/ Cluster of Differentiation 200 receptor 1 (CD200/CD200R), P2X7R), and mitochondrial biogenesis pathways, with a focus on normalizing glial phenotypes rather than simply suppressing pathology. Interventions that restore neuroglial homeostasis at the earliest stages of disease may hold the greatest potential to delay or prevent progression. Given the complexity of glial phenotypes and molecular isoform diversity, a comprehensive, multitargeted approach is essential for mitigating Alzheimer’s disease and related neurodegenerative disorders. This review not only synthesizes pathogenesis but also highlights therapeutic opportunities, offering what we believe to be the first concise overview of the principal hypotheses implicating glial cells in neurodegeneration. Rather than focusing on isolated mechanisms, our goal is a holistic perspective—integrating diverse glial processes to enable comparison across interconnected pathological conditions. Full article

Background/Objectives: Semen Ziziphi Spinosae (SZS), a medicinal and edible traditional Chinese herb, has been widely used to treat insomnia. As critical regulators of the central nervous system, astrocytes play a pivotal role in maintaining sleep homeostasis. However, the mechanisms by which SZS modulates astrocytic function to improve sleep remain unclear. Methods: In this study, we employed an integrated transcriptomics and metabolomics approach to investigate the protective effects of SZS extract against lipopolysaccharide (LPS)-induced inflammatory injury and metabolic dysfunction in astrocytes. Results: Transcriptomic analysis revealed that SZS ameliorates cellular damage (including apoptosis, autophagy, and cell cycle dysregulation) through a FOXO3-centric signaling network. Concurrently, SZS restored cellular energy metabolism by increasing ATP production and reducing Ca²⁺ overload, thereby activating the AMPK signaling pathway to support normal astrocytic function. Metabolomic profiling further demonstrated that SZS-mediated restoration of energy homeostasis sustains ABC transporter activity, which in turn modulates neurotransmitter (serotonin, L-glutamic acid, adenosine), metabolic mediators (leukotrienes, palmitoylethanolamide, succinic acid), and nucleotide (uridine 5′-diphosphate). These coordinated changes normalized GABAergic synapse activity and neuroactive ligand receptor interactions, ultimately resolving neural metabolic network disturbances. Conclusions: Our findings elucidate a novel FOXO3-energy metabolism-ABC transporter axis through which SZS extract attenuates neuroinflammation and metabolic dysfunction in astrocytes and exerts sleep-promoting and neuroprotective effects. This study provides a scientific foundation for understanding the modern pharmacological mechanisms of traditional Chinese medicine in insomnia treatment, highlighting astrocytic regulation as a potential therapeutic target. Full article

This study investigates the development and evaluation of anti-photoaging creams enriched with natural extracts from avocado, apple, and kiwi by-products, with and without nanobubbles (NBs), focusing on their antioxidant, photoprotective, anti-inflammatory, and antiplatelet properties. Extract-containing creams showed significantly higher antioxidant capacity, particularly in the ferric reducing antioxidant power (FRAP) assay (S: 710.4 ± 344.3, NB: 566.3 ± 185.0, X: 202.8 ± 145.6 μmol TE/g DW at production; S: 631.7 ± 277.8, NB: 1019.3 ± 574.0, X: 449.8 ± 43.9 μmol TE/g DW after 1 month; p < 0.05), indicating up to a 250% improvement compared to the base cream and stable antioxidant activity during storage. The sun protection factor (SPF) increased in extract-containing creams after storage (8.7 ± 0.8 → 9.5 ± 0.6; p < 0.05). Attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) with Strat-M^® membranes revealed enhanced penetration of active compounds in enriched creams, while NBs did not significantly change absorption profiles. Platelet aggregation assays showed markedly lower half maximal inhibitory concentration (IC50) values in extract-enriched creams compared to the base cream for both the platelet-activating factor (PAF) pathway (S: 300.0 ± 42.0, NB: 258.0 ± 31.0 vs. X: 685.0 ± 35.0; after 1 month S: 325.0 ± 50.0, NB: 275.0 ± 42.0 vs. X: 885.0 ± 112.0; p < 0.05) and the adenosine diphosphate (ADP) pathway (S: 450.0 ± 65.0, NB: 400.0 ± 31.0 vs. X: 880.0 ± 58.0; after 1 month S: 470.0 ± 52.0, NB: 412.0 ± 42.0 vs. X: 1102.0 ± 125.0; p < 0.05). In silico analysis was also performed to demonstrate the ligand/protein complex with the strongest affinity to the PAF receptor. Overall, these findings highlight the potential of fruit by-products as sustainable, multifunctional cosmetic ingredients supporting circular economy principles. Full article

Adenosine receptor (AR) antagonists have attracted considerable interest due to their therapeutic potential in a wide range of pathological conditions, including neurological, cardiovascular, and inflammatory disorders. Although a large number of AR antagonists have been developed worldwide, the interest in new derivatives remains high, and achieving subtype selectivity continue to be a major challenge. This review summarizes our research on adenosine receptor antagonists, highlighting the discovery of potent and selective compounds for the diverse AR subtypes across various chemical classes. Specifically, the paper focuses on the study of the triazolo[4,3-a]quinoxalin-1-one (TQX) and pyrazolo[3,4-c]quinoline (PQ) series, along with their simplified analogues, which have yielded highly potent and selective AR antagonists. An overview of the structure–activity relationship (SAR) studies and molecular docking investigations is provided, emphasizing the structural requirements for A_2A and A₃ receptor–ligand interaction. In addition, we present pharmacological studies of selected AR antagonists, in various in vitro and in vivo models of pain, depression, neuroinflammation-related diseases, and cancer. Full article

Ischemic heart disease (IHD) represents a leading cause of global morbidity and mortality. Despite significant advances in treatment achieved over recent decades, as well as various therapeutic strategies available to manage IHD progression currently, the global incidence of this disorder remains high. This review examines essential cell biology aspects of adenosine receptors (ARs), along with the effects of known synthetic small-molecule AR ligands, to provide an up-to-date view on the therapeutic potential towards IHD treatment. In particular, we report here advancements made on a selection of AR synthetic ligands that have demonstrated efficacy in pre-clinical or clinical studies, thereby holding promise as new therapeutic candidates in the field of IHD. Although this work adds further evidence that clinically valid small-molecule therapeutic agents targeting ARs exist, their use represents an emerging area, with most drug prototypes still in the pre-clinical developmental stage and many lacking large-scale clinical trials. The future lies in identifying improved AR synthetic ligands with enhanced efficacy and selectivity, as well as reduced adverse side effects, along with establishing a platform of specific and diversified pre-clinical tests, to inform in turn the resulting clinical investigations. Full article

Spurred by the enormous therapeutic success of glucagon-like peptide-1 receptor (GLP-1R) agonists (GLP1-RAs) against diabetes and obesity, glucagon family receptor pharmacology has garnered a tremendous amount of interest. Glucagon family receptors, e.g., the glucagon receptor itself (GCGR), the GLP-1R, and the glucose-dependent insulinotropic peptide receptor (GIPR), belong to the incretin receptor superfamily, i.e., receptors that increase blood glucose-dependent insulin secretion. All incretin receptors are class B1 G protein-coupled receptors (GPCRs), coupling to the G_s type of heterotrimeric G proteins which activates adenylyl cyclase (AC) to produce cyclic adenosine monophosphate (cAMP). Most GPCRs undergo desensitization, i.e., uncouple from G proteins and internalize, thanks to interactions with the βarrestins (arrestin-2 and -3). Since the βarrestins can also mediate their own G protein-independent signaling, any given GPCR can theoretically signal (predominantly) either via G proteins or βarrestins, i.e., be a G protein- or βarrestin-“biased” receptor, depending on the bound ligand. A plethora of experimental evidence suggests that the GLP-1R does not undergo desensitization in physiologically relevant tissues in vivo, but rather, it produces robust and prolonged cAMP signals. A particular property of constant cycling between the cell membrane and caveolae/lipid rafts of the GLP-1R may underlie its lack of desensitization. In contrast, GIPR signaling is extensively mediated by βarrestins and the GIPR undergoes significant desensitization, internalization, and downregulation, which may explain why both agonists and antagonists of the GIPR exert the same physiological effects. Here, we discuss this evidence and make a case for the GLP-1R being a phenotypically or functionally G_s-selective receptor. We also discuss the implications of this for the development of GLP-1R poly-ligands, which are increasingly pursued for the treatment of obesity and other diseases. Full article

Background/Objectives: Kidneys are fatty acid (FA)-consuming organs that use adenosine triphosphate (ATP) for tubular functions, including endocytosis for protein reabsorption to prevent urinary protein loss. Peroxisome proliferator-activated receptor α (PPARα) is a master regulator of FA metabolism and energy production, with high renal expression. Although polyunsaturated fatty acids (PUFAs) are essential nutrients that are natural PPARα ligands, their role in tubular protein reabsorption remains unclear. As clinical PUFA deficiency occurs in humans under various conditions, we used a mouse model that mimics these conditions. Methods: We administered a 2-week intraperitoneal protein-overload (PO) treatment to mice that had been continuously fed a PUFA-deficient diet. We compared the phenotypic changes with those in mice fed a standard diet and those in mice fed a PUFA-deficient diet with PUFA supplementation. Results: In the absence of PO, the PUFA-deficient diet induced increased lysosomal autophagy activation; however, other phenotypic differences were not detected among the diet groups. In the PO experimental condition, the PUFA-deficient diet increased daily urinary protein excretion and tubular lysosomes; suppressed adaptive endocytosis activation, which was probably enhanced by continuous autophagy activation; and worsened FA metabolism and PPARα-mediated responses to PO, which disrupted renal energy homeostasis. However, these changes were attenuated by PUFA supplementation at the physiological intake level. Conclusions: PUFAs are essential nutrients for the tubular adaptive reabsorption response against urinary protein loss. Therefore, active PUFA intake may be important for patients with kidney disease-associated proteinuria, especially those with various PUFA deficiency-inducing conditions. Full article

Equine follicle-stimulating hormone receptor (eFSHR) contains four extracellular N-linked glycosylation sites, which play important roles in agonist-induced signal transduction. Glycosylation regulates G protein-coupled receptor mechanisms by influencing folding, ligand binding, signaling, trafficking, and internalization. Here, we examined whether the glycosylated sites in eFSHR are necessary for cyclic adenosine monophosphate (cAMP) signal transduction and the phosphate extracellular signal-regulated kinase 1/2 (pERK1/2) response. We constructed mutants (N191Q, N199Q, N268Q, and N293Q) of the four N-linked glycosylation sites in eFSHR using site-directed mutagenesis. In wild-type (wt) eFSHR, the cAMP response gradually increased dose-dependently, displaying a strong response at the EC₅₀ and Rmax. Two mutants (N191Q and N199Q) considerably decreased the cAMP response. Both EC₅₀ values were approximately 0.46- and 0.44-fold compared to that of the eFSHR-wt, whereas Rmax levels were 0.29- and 0.45-fold compared to eFSHR-wt because of high-ligand treatment. Specifically, the EC₅₀ and Rmax values in the N268Q mutant were increased 1.23- and 1.46-fold, respectively, by eFSHR-wt. pERK1/2 activity in eFSHR-wt cells was rapid, peaked within 5 min, consistently sustained until 15 min, and then sharply decreased. pERK1/2 activity in the N191Q mutant showed a pattern similar to that of the wild type, despite impaired cAMP responsiveness. The N199Q mutant showed low pERK1/2 activity at 5 and 15 min. Interestingly, pERK1/2 activity in the N268Q and N298Q mutants was similar to that of eFSHR-wt at 5 min, but neither mutant showed any signaling at 15 min, despite displaying high cAMP responsiveness. Overall, eFSHR N-linked glycosylation sites can signal to pERK1/2 via PKA and the other signals, dependent on G protein coupling and β-arrestin-dependent recruitment. Our results provide strong evidence for a new paradigm in which cAMP signaling is not activated, yet pERK1/2 cascade remains strongly induced. Full article

Parkinson’s disease (PD) represents a growing challenge to global health, as it involves millions of people. The high grade of disability is due to the loss of dopaminergic neuron activity, and levodopa is the gold-standard therapy used to restore dopamine in the dopamine-denervated regions. Another therapeutic approach is the use of A_2A adenosine receptor antagonists and, among them, istradefylline is the only one currently approved for therapy in association with levodopa. In this work, we synthesized A_2A adenosine receptor antagonists represented by 9-ethyl-2,8-disubstituted adenine derivatives, which were tested at human adenosine receptors in binding and functional assays. These compounds showed A_2A adenosine receptor-binding affinities in the low nanomolar range and 1, 4, and 5 exhibited good potency in the functional assays. Hence, they were evaluated in in vivo rat models of PD, where they were demonstrated to revert haloperidol-induced catalepsy and potentiate levodopa-induced contralateral rotations in 6-hydroxydopamine-lesioned rats. The most potent derivative, 4, was then evaluated in the tacrine model, where it reduced the tremulous jaw movements, therefore demonstrating an action on parkinsonian tremor. These data revealed 8-ethoxy-2-phenethoxy-9-ethyladenine (4) as an A_2A adenosine receptor antagonist endowed with antiparkinsonian effects and as a good candidate to treat the disease. Full article

Glioblastoma (GBM) is the most common malignant primary brain tumor, resulting in poor survival despite aggressive therapies. GBM is characterized by a highly heterogeneous and immunosuppressive tumor microenvironment (TME) made up predominantly of infiltrating peripheral immune cells. One significant immune cell type that contributes to glioma immune evasion is a population of immunosuppressive cells, termed myeloid-derived suppressor cells (MDSCs). Previous studies suggest that a subset of myeloid cells, expressing monocytic (M)-MDSC markers and dual expression of chemokine receptors CCR2 and CX3CR1, utilize CCR2 to infiltrate the TME. This study evaluated the mechanism of CCR2⁺/CX3CR1⁺ M-MDSC differentiation and T cell suppressive function in murine glioma models. We determined that bone marrow-derived CCR2⁺/CX3CR1⁺ cells adopt an immune suppressive cell phenotype when cultured with glioma-derived factors. Glioma-secreted CSF1R ligands M-CSF and IL-34 were identified as key drivers of M-MDSC differentiation while adenosine and iNOS pathways were implicated in the M-MDSC suppression of T cells. Mining a human GBM spatial RNAseq database revealed a variety of different pathways that M-MDSCs utilize to exert their suppressive function that is driven by complex niches within the microenvironment. These data provide a more comprehensive understanding of the mechanism of M-MDSCs in glioblastoma. Full article