Search Results (318)

The presence of aberrant double-stranded DNA (dsDNA) in the cytoplasm of cells is sensed by unique pattern recognition receptors (PRRs) to trigger innate immune response. The cyclic GMP–AMP synthase (cGAS)–stimulator of interferon genes (STING) signaling pathway is activated by the presence of non-self or mislocalized self-dsDNA from nucleus or mitochondria released in response to DNA damage or cellular stress in the cytoplasm. Activation of cGAS leads to the synthesis of the second messenger cyclic GMP–AMP (cGAMP), which binds and activates STING, triggering downstream signaling cascades that result in the production of type I interferons (IFNs) and proinflammatory cytokines. Here, we show that diverse immunostimulatory dsDNA ligands and chemotherapy agents like Doxorubicin and Taxol trigger the integrated stress response (ISR) by activating endoplasmic reticulum (ER) stress kinase, protein kinase RNA-like ER kinase (PERK), in addition to the canonical IFN pathways. PERK-mediated phosphorylation and inactivation of the alpha subunit of eukaryotic translation initiation factor-2 (eIF2α) result in the formation of stress granules (SGs). SG formation by dsDNA was significantly reduced in PERK knockout cells or by inhibiting PERK activity. Transcriptional induction of IFNβ and cytokines, ISR signaling, and SG formation by dsDNA was dampened in cells lacking PERK activity, STING, or key stress-granule nucleating protein, Ras-GAP SH3 domain-binding protein 1 (G3BP1), demonstrating an important role of the signal transduction pathway mediated by STING and SG assembly. Lastly, STING regulates reactive oxygen species (ROS) production in response to DNA damage, highlighting the crosstalk between DNA sensing and oxidative stress pathways. Together, our data identify STING–PERK–G3BP1 signaling axis that couples cytosolic DNA sensing to stress response pathways in maintaining cellular homeostasis. Full article

G protein-coupled receptors (GPCRs) are key regulators of cerebrovascular function, integrating vascular, inflammatory, and neuronal signaling within the neurovascular unit (NVU). Increasing evidence suggests that GPCR actions are highly dependent on cell type, signaling pathway, and disease stage, leading to distinct, and sometimes opposing, effects during acute ischemic injury and post-stroke recovery. In this review, we reorganize GPCR signaling mechanisms using a disease-stage-oriented and NVU-centered framework. We synthesize how GPCR-mediated intercellular communication among neurons, glial cells, and vascular elements dynamically regulates cerebral blood flow, neuroinflammation, blood–brain barrier (BBB) integrity, and neuronal circuit remodeling. Particular emphasis is placed on phase-dependent GPCR signaling, highlighting receptors whose functions shift across acute injury, secondary damage, and recovery phases. We further critically evaluated the translational implications of GPCR-targeted therapies, discussing why promising preclinical neuroprotection has frequently failed to translate into clinical benefit. By integrating molecular mechanisms with temporal dynamics and translational constraints, this review provides a framework for the rational development of cell-type and stage-specific GPCR-based therapeutic strategies in cerebrovascular disease. Full article

Background: This study systematically investigates the therapeutic effects of naringenin (NAR) and oleuropein (OLE) on prostate cancer through miR-155-5p regulation. Methods: Experimental studies conducted on MAT-LyLu prostate cancer cell lines revealed that the application of NAR (50 μM) and OLE (75 μM) significantly increased miR-155-5p expression by 2.89-fold and 1.74-fold, respectively (p < 0.05). Bioinformatics analyses have indicated that miR-155-5p interacts with critical oncogenic pathways such as KRAS, CDK2, NF-κB, and TGF-β/Smad2. Computational analyses have revealed that miR-155-5p interacts with 16 critical oncogenic targets, including KRAS and CDK2. Molecular docking studies showed that NAR binds to the Switch I/II region of KRAS with a binding energy of −8.2 kcal/mol, while OLE binds to the ATP-binding pocket of CDK2 with an affinity of −9.1 kcal/mol. Pharmacokinetic evaluations revealed that NAR indicated high oral bioavailability (93.763% HIA) and full compliance with Lipinski’s rules, while OLE required advanced formulation strategies due to its high polarity. Network pharmacology analyses have shown that NAR affects lysosomal functions and enzyme regulation, while OLE affects G protein-coupled receptors and oxidoreductase activity. Results: Results indicate that NAR and OLE exhibit antitumor effects through multiple mechanisms by increasing miR-155-5p expression and inhibiting critical oncogenic targets in prostate cancer. Conclusion: Findings suggest that the dietary intake of these natural compounds (citrus and olive products) should be considered in prostate cancer prevention strategies, shedding light on the epigenetic mechanisms of polyphenols in cancer treatment and contributing to the development of new therapeutic strategies. Full article

Autoinflammatory diseases involve recurrent systemic inflammation caused by dysregulated innate immunity, arising from genetic or multifactorial mechanisms, as seen in periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome. About 10% of PFAPA patients show autosomal dominant inheritance. We describe a three-generation family with a PFAPA-like recurrent fever syndrome displaying clear autosomal dominant transmission. All affected individuals tested negative on a diagnostic panel of 13 known autoinflammatory genes. Whole-exome sequencing was performed in two distantly related affected members, followed by variant filtering, segregation analysis, and phenotype-based prioritization. A single heterozygous missense variant in RXFP1, c.154G>A p.(Asp52Asn), co-segregated with disease in all affected relatives. This variant is extremely rare in population databases, absent from ClinVar, present in COSMIC, and predicted as damaging by REVEL and CADD. RXFP1, not previously implicated in autoinflammatory or innate immune disorders, encodes the relaxin family peptide receptor 1, a G protein–coupled receptor involved in extracellular matrix regulation, anti-fibrotic pathways, and modulation of inflammatory cytokine production. Protein network analysis showed interactions with RLXN1-3, inflammatory mediators, PTGDR, ADORA2B, and C1QTNF8, supporting an immunomodulatory function. This is the first report linking RXFP1 variation to a hereditary recurrent fever syndrome, identifying relaxin signalling as a potential immune regulatory pathway. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) involves early disturbances such as excessive lipid accumulation, sterile inflammation, and hepatocellular stress. The results of recent studies have highlighted extracellular ATP and its metabolite adenosine (Ado) as damage-associated molecular patterns (DAMPs) that drive inflammation, endoplasmic reticulum (ER) stress, and steatosis, contributing to MASLD progression. Although vitamin E is clinically used for its antioxidant and anti-inflammatory properties, it remains unclear whether its therapeutic effects involve modulation of DAMP-associated signaling. To address this gap, we used transgenic zebrafish expressing a liver-specific G-protein-coupled receptor activation-based adenosine sensor (GRAB_Ado). We found that a high-cholesterol diet markedly increased hepatic extracellular Ado levels, combined with inflammatory and ER stress-associated gene expression. Vitamin E significantly reduced extracellular Ado levels and hepatic lipid accumulation. Based on RNA sequencing results, vitamin E restored the expression of genes encoding calcium-handling proteins, including atp2a1 and atp1b1b. These genes encode components of the sarco/ER Ca²⁺-ATPase (SERCA) machinery, which is essential for maintaining ER Ca²⁺ homeostasis and preventing stress-induced hepatic injury. CDN1163-mediated SERCA activation phenocopied the protective effect of vitamin E, supporting a Ca²⁺-dependent mechanism. Together, these findings highlight extracellular Ado signaling and impaired SERCA-mediated Ca²⁺ regulation as early drivers of MASLD and demonstrate that vitamin E ameliorates steatosis by targeting both pathways. Full article

Fibrosis manifests as an excessive accumulation of fibrillar collagen in tissues where secreted collagen exceeds degradation. Myofibroblasts are important contributors to the excessive collagen seen in fibrotic lesions. Accordingly, targeting signaling pathways that enhance collagen degradation and subdue myofibroblast differentiation has the potential to optimize collagen remodeling and improve organ fibrosis. One of the most promising molecular targets for therapeutic development is the G protein-coupled receptor (GPCR) family, which is diverse, cell-type-specific, multi-pass transmembrane receptors that participate in the regulation of extracellular matrix remodeling. GPCRs are categorized into multiple subclasses, some of which activate signaling cascades that can augment or reduce pro-fibrotic processes, depending on which Gα class is activated. Specifically, activation of Gαs GPCR stimulates production of the second messenger, cyclic adenosine monophosphate (cAMP), which generally inhibits pro-fibrotic mediators. A related, second approach for control of fibrosis is the blockade of a specific mechanosensitive, Ca²⁺-permeable channel that is implicated in fibrosis and contributes to myofibroblast differentiation, the transient receptor potential vanilloid type 4 (TRPV4). In health, TRPV4 activation regulates collagen remodeling, but when dysregulated, it promotes pro-fibrotic gene expression through mechanosensitive transcription factors. In this review, we focus on the functions of the Gαs GPCR pathway and TRPV4 activation through the interplay of the second messengers cAMP and Ca²⁺ ions. Ca²⁺ influx modulates cAMP levels by regulating phosphodiesterases and adenylyl cyclases. We consider evidence that Gαs GPCR and TRPV4 signaling pathways interact antagonistically to either promote collagen degradation or to increase the formation of myofibroblasts through signaling that involves cAMP and Ca²⁺ conductance. Coordinated activation of the Gαs GPCR pathway and inhibition of TRPV4 could provide a novel, bimodal approach to control tissue fibrosis. Full article

Taste receptor type 1 member 3 (TAS1R3) is a class C G protein-coupled receptor (GPCR) traditionally associated with taste perception. While its role in insulin secretion is established, its contribution to skeletal muscle glucose uptake, a process responsible for 70–80% of postprandial glucose disposal, remains unclear. TAS1R3 expression was assessed in skeletal muscle biopsies from non-diabetic and type 2 diabetes (T2D) donors using qPCR and immunoblotting. Functional studies in human LHCN-M2 myotubes involved TAS1R3 inhibition with lactisole or siRNA-mediated knockdown, followed by the measurement of insulin-stimulated glucose uptake using radiolabeled glucose assays. Rac1 activation and phospho-cofilin were analyzed by G-LISA and Western blotting, and Gαq/11 involvement was tested using YM-254890. TAS1R3 mRNA and protein levels were significantly reduced in T2D skeletal muscle. Pharmacological inhibition or the knockdown of TAS1R3 impaired insulin-stimulated glucose uptake in myotubes. TAS1R3 regulates skeletal muscle glucose uptake through a non-canonical insulin signaling pathway involving Rac1 and phospho-cofilin, independent of IRS1-AKT and Gαq/11 signaling. These findings identify TAS1R3 as a key determinant of Rac1-mediated glucose uptake and a potential therapeutic target for improving insulin sensitivity in T2D. Full article

Sphingosine-1-phosphate receptors (S1PRs) are a family of G protein-coupled transmembrane proteins that play essential roles across nearly all organ systems, including the regulation of pulmonary physiology and immune responses. Expressed across diverse lung cell types, S1PRs mediate critical biological processes such as vascular barrier integrity, immune cell trafficking, and inflammation. While the signaling pathways and physiological functions of S1PR1 and S1PR3 have been extensively characterized, the role of S1PR2 remains less clearly defined and context-dependent. In this review, we summarize current knowledge on S1PR2 signaling within major pulmonary cell populations and explore its contribution to lung homeostasis and disease. By synthesizing evidence from molecular, cellular and in vivo studies, this review aims to summarize the current understanding of S1PR2 signaling across major pulmonary cell populations and its roles in lung homeostasis and disease. The findings of this study could help develop new strategies for treating pulmonary disorders and other diseases by targeting S1PR2. Full article

Renal cell carcinoma (RCC) is a biologically heterogeneous malignancy accounting for 3% of adult cancers globally. Despite advances in immune checkpoint inhibitors (ICIs) and vascular endothelial growth factor (VEGF)-targeted therapies, durable disease control remains elusive for many patients. Increasing evidence implicates the acidic tumour microenvironment (TME) as a critical mediator of RCC progression, immune evasion, and therapeutic resistance. Solid tumours, including RCC, exhibit reversed pH gradients, characterised by acidic extracellular (pH 6.2–6.9) and alkaline intracellular conditions. This dysregulation arises from enhanced glycolysis, hypoxia-driven lactate accumulation, and the overexpression of pH-regulating enzymes such as carbonic anhydrase (CA9). Acidic TMEs impair cytotoxic T-cell and NK-cell activity, promote tumour-associated macrophage (TAM) polarisation towards an immunosuppressive phenotype, and upregulate alternative immune checkpoints. These mechanisms collectively undermine ICI efficacy and contribute to primary and secondary treatment resistance. Proton-sensing G-protein-coupled receptors (GPCRs), notably GPR65, have emerged as pivotal mediators linking extracellular acidosis to immune dysfunction. Preclinical studies demonstrate that GPR65 antagonists restore anti-tumour immune activity by reversing acidosis-driven immunosuppression and enhancing antigen processing. In RCC models, selective GPR65 inhibitors have shown the ability to reduce immunosuppressive cytokine IL-10 production, induce immunoproteasome activation, and synergise with anti-PD-1 therapy. The first-in-class GPR65 inhibitor, PTT-4256, is now under evaluation in the Phase I/II RAISIC-1 trial (NCT06634849) in solid tumours, including RCC. Targeting acid-sensing pathways represents a novel and promising therapeutic strategy in RCC, aiming to remodel the TME and overcome ICI resistance. Integrating GPR65 inhibition with existing immunotherapies may define the next era of RCC management, warranting continued translational and clinical investigation. Full article

Background: The gut microbiota plays a fundamental role in metabolic and immune homeostasis through the production of short-chain fatty acids (SCFAs). These metabolites influence mitochondrial biogenesis, muscle energetics, epithelial barrier stability, and inflammatory regulation via G-protein-coupled receptors, AMPK–PGC-1α signaling, and epigenetic remodeling. Objective: This review synthesizes current evidence on the gut–muscle–immune axis, emphasizing how dietary fermentable substrates, microbial cross-feeding interactions, and structured exercise modulate SCFA production and shape host physiological adaptation. Methods: We integrated findings from human and animal studies, multi-omic analyses, metabolomic and microbiome research, and exercise physiology to outline mechanistic links between microbial metabolism and systemic resilience. Results: Key mechanistic pathways connecting dietary fiber fermentation to mitochondrial function, redox regulation, immune homeostasis, and metabolic plasticity are summarized. We further present the Targeted Gut Protocol 2.0, a conceptual 12-week framework combining fiber-diversity targets, lactate-guided exercise periodization, biomarker monitoring, and adaptive feedback mechanisms to enhance endogenous SCFA availability. Conclusions: SCFA-driven metabolic plasticity provides an integrative model through which lifestyle behaviors can modulate host physiology. Future research should prioritize standardized sampling approaches, causal inference methods, multi-omic integration, and AI-supported personalization to refine mechanistic understanding and strengthen translational potential. Full article

Beta-arrestin 1 (ARRB1) is a multifunctional adaptor protein that regulates diverse signaling pathways beyond its canonical role in G-protein-coupled receptor desensitization. While ARRB1 has been implicated in cancer progression, its role in modulating host immunity against multiple myeloma (MM) remains unexplored. Here, we demonstrate that host ARRB1 deficiency significantly enhances anti-myeloma immunity and prolongs survival in a syngeneic murine MM model. Using Vk*MYC myeloma cells transplanted into wild-type and ARRB1 knockout mice, we show that ARRB1 deficiency in the host microenvironment promotes robust T cell infiltration and activation while reducing immunosuppressive myeloid populations. Notably, ARRB1 knockout mice exhibited markedly decreased programmed cell death protein-1 (PD-1) expression on both T cells and myeloid-derived suppressor cells, indicating reduced immune exhaustion. Furthermore, ARRB1 deficiency conferred protection against myeloma-induced bone disease, suggesting a dual role in immune regulation and bone homeostasis. These findings establish ARRB1 as a critical negative regulator of host anti-myeloma immunity and identify it as a potential therapeutic target for enhancing immunotherapy efficacy in MM. Full article

Background/Objectives: Seasonal reproduction in mammals is primarily regulated by the hypothalamic–pituitary–ovarian (HPO) axis, yet its molecular mechanisms in subterranean rodents living in light-restricted environments remain poorly understood. This study aimed to characterize the transcriptional regulation of the HPO axis during seasonal estrus in the Manchurian zokor (Myospalax psilurus, M. psilurus), a fossorial rodent exhibiting distinct breeding cycles despite perpetual darkness. Methods: Hypothalamic, pituitary, and ovarian tissues were collected from female zokors during estrus and anestrus (n = 5 per group). RNA sequencing was performed, followed by de novo transcriptome assembly and bioinformatic analyses. Differentially expressed genes (DEGs) were identified using edgeR, and functional enrichment was assessed via GO and KEGG analyses. Key DEGs were validated by RT-qPCR. Results: A total of 513, 292, and 138 DEGs were identified in the hypothalamus, pituitary, and ovary, respectively. GO analysis highlighted enrichment in G-protein-coupled receptor signaling, oxidation–reduction processes, and calcium ion binding. KEGG pathway analysis revealed significant enrichment of the neuroactive ligand–receptor interaction pathway across all three tissues. Key candidate genes included Trh and Mc3r in the hypothalamus, Pitx2 and NR4A2 in the pituitary, and PTGER2 and Sphk1 in the ovary. Conclusions: This study provides the first comprehensive transcriptomic profile of the HPO axis in Manchurian zokors during seasonal estrus. The neuroactive ligand–receptor interaction pathway appears central to reproductive regulation, and several tissue-specific genes were identified as potential regulators of seasonal breeding. These findings enhance our understanding of reproductive adaptation in subterranean mammals and offer a foundation for further functional studies. Full article

Background/Objectives: Osteoporosis is caused by excessive osteoclast activation via the receptor activator nuclear factor kappa B ligand (RANKL), which is released from osteoblasts or osteocytes. RANKL regulates osteoclast activity by binding to the receptor activator of nuclear factor kappa B (RANK) in the canonical pathway or leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4) in the non-canonical pathway. In this study, we attempted to develop an intact small-fragment protein based on RANKL by removing the RANK-binding site and transforming the amino acid residues at crucial sites to inhibit osteoclast activity and treat osteoporosis. Methods: We expressed a small-fragment variant of RANKL as a soluble glutathione S-transferase (GST) or 6x histidine (His)-tagged fusion protein using a GST- or His-binding domain tag expression vector system. To generate an intact form of small-fragment RANKL, ribosome-inactivating protein–His-fusion RANKL was purified using HisTrap affinity chromatography and treated with tobacco etch virus nuclear inclusion endopeptidase to remove the His-tag fusion protein. Tartrate-resistant acid phosphatase (TRAP) and bone resorption pit formation assays were performed to analyze the inhibitory effects on osteoclast differentiation and activation. Results: The intact forms of 225RANKL295P and 225RANKL295A showed the strongest inhibitory effects on TRAP activity and bone resorption pit formation. Conclusions: Using an optimal construct design, a large and diverse range of small RANKL fragments could be generated. This suggests that the generation of small-fragment RANKL provides a promising avenue for the advancement of novel therapeutic approaches to osteoporosis. Full article

Sepsis is a life-threatening syndrome marked by a dysregulated host response to infection, resulting in systemic inflammation, organ dysfunction, and high mortality globally. Despite advancements in supportive care, effective immunomodulatory therapies remain elusive, necessitating exploration of novel biological pathways and subsequent therapeutic development. The endocannabinoid system (ECS), which regulates immune function and homeostasis, has emerged as a key modulator of immunological and metabolic pathways central to sepsis pathophysiology. The ECS mediates its effects through endogenous ligands, G-protein-coupled cannabinoid receptors (CB1 and CB1), and regulatory enzymes that control its synthesis and degradation. Following PRISMA-ScR guidelines, this scoping review synthesizes current evidence on the mechanistic roles of ECS components in experimental and clinical models of sepsis, identifies knowledge gaps, and delineates future areas of work. A comprehensive literature search across multiple databases without restrictions on date or publication type was executed to ensure broad coverage of original studies investigating ECS mechanisms and their intersection with sepsis and septic shock. Across 53 studies, CB2 receptor activation was consistently associated with anti-inflammatory process, organ-protective outcomes, and increased survival rates against septic challenges in preclinical rodent models. CB1 receptor activation trends, however, showed context dependent outcomes. Central antagonism improved hemodynamics and survival rate, but peripheral effects varied with cell type and timing. Non-canonical ECS components (TRPV1, GPR55, PPAR-α, FAAH, MAGL) also contributed to neuroimmune and metabolic regulation. Limited clinical data linked ECS lipid profiles and gene expression with sepsis severity and outcomes. Collectively, ECS modulation, particularly CB2 agonism, TRPV1 activation, and FAAH/MAGL inhibition, shows promise in mitigating sepsis-induced inflammation and organ dysfunction. However, complex, context-dependent effects, especially involving CB1, highlight the need for precision-targeted therapeutic approaches. Further preclinical research is needed to expand generalizable trends to allow translational research to refine ECS-based interventions for sepsis management. Full article

This study investigated the interactive effects of dietary vitamin A (VA) and all-trans retinoic acid (ATRA) on growth performance and intestinal health in broilers. A total of 432 one-day-old male Arbor Acres chicks were assigned to a 2 × 3 factorial design with two VA levels (2000 and 6000 IU/kg) and three ATRA levels (0, 0.25, and 0.50 mg/kg). The maize–soybean meal basal diet contained 180 IU/kg VA without extra VA supplementation. Results showed that compared with 0 mg/kg ATRA, 0.50 mg/kg ATRA enhanced average daily gain (ADG) during days 1–21 (p < 0.05). Compared with 2000 IU/kg VA, 6000 IU/kg VA improved body weight on day 35 as well as ADG and feed intake during days 22–35 and reduced feed conversion ratio over the entire trial (p < 0.05). There were VA × ATRA interactions for the ratio of villus height (VH) to crypt depth (CD) in duodenum as well as VH and CD in ileum on day 21 (p < 0.05). The 0.25 mg/kg ATRA decreased duodenal VH/CD and ileal VH in broilers fed 2000 and 6000 IU/kg VA, respectively (p < 0.05). The 0.50 mg/kg ATRA increased ileal VH in broilers fed both 2000 and 6000 IU/kg VA (p < 0.05). When birds were fed 6000 IU/kg VA, 0.50 mg/kg ATRA increased ileal CD compared with 0.25 mg/kg CD (p < 0.05). On day 35, compared with 0 mg/kg ATRA, 0.25 mg/kg ATRA increased ileal VH while 0.50 mg/kg ATRA decreased ileal CD, and both of them increased ileal VH/CD (p < 0.05). The VA × ATRA interactions for mRNA expression of jejunal Mucin5ac on day 21 and jejunal Occludin, Claudin-1, Mucin 2, leucine-rich-repeat-containing G-protein-coupled receptor 5⁺ (Lgr5⁺), zinc and ring finger 3 (Znrf3), and secreted phosphoprotein 1 (SPP1) on day 35 were detected (p < 0.05). Dietary 0.50 mg/kg ATRA up-regulated jejunal Mucin5ac expression in broilers fed 6000 IU/kg VA on day 21 as well as Claudin-1, Znrf3, and SPP1 expression broilers fed 2000 IU/kg VA on day 35 (p < 0.05). The 0.25 mg/kg ATRA down-regulated Occludin expression in broilers fed 6000 IU/kg VA on day 35 (p < 0.05). The 0.25 mg/kg ATRA decreased and increased Lgr5⁺ expression on day 35 in broilers fed 2000 and 6000 IU/kg VA, respectively (p < 0.05). Both 0.25 and 0.50 mg/kg ATRA down-regulated Mucin-2 expression in broilers fed 2000 IU/kg VA on day 35 (p < 0.05). The VA × ATRA interactions were observed for jejunal retinol dehydrogenase 10 (RDH10), cytochrome P450, family 26, subfamily A, polypeptide 1 (CYP26A1), retinoic acid receptor (RAR) α, and RARβ expression on days 21 and 35 (p < 0.05). Both 0.25 and 0.50 mg/kg up-regulated RDH10, CYP26A1, and RARβ expression in broilers fed 6000 IU/kg VA (p < 0.05). The RARα expression was up-regulated by 0.50 and 0.25 mg/kg ATRA on days 21 and 35, respectively (p < 0.05). Plasma metabolomics identified 269 VA- and 185 ATRA-associated differential metabolites, primarily enriched in lipid metabolism, vitamin digestion and absorption, and bacterial infection pathways. In conclusion, dietary 0.50 mg/kg ATRA and 6000 IU/kg VA enhanced growth performance, intestinal integrity, and VA metabolism, partly through activation of retinoic acid receptors and modulation of plasma lipid metabolism. Full article