Acta Pharmacologica Sinica最新文献

Enteric glial cells (EGCs) play an important role in the pathogenesis of irritable bowel syndrome (IBS). Phosphodiesterase-4 (PDE4) functions as a catalyzing enzyme targeting hydrolyzation of intracellular cyclic adenosine monophosphate (cAMP). Increased PDE4 activity promotes excessive production of pro-inflammatory cytokines and chemokines in various immune and epithelial cells, exacerbating immune cell activation and infiltration in inflamed tissues, inhibition of PDE4 has been proven to be an important strategy for inflammatory and autoimmune diseases. In this study we investigated the pathological role of PDE4 and the therapeutic effects of a PDE4 inhibitor apremilast in IBS. 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced IBS model was established in mice, the mice were treated with apremilast (50 mg/kg, i.g.) for 7 days. After treatment, the intestinal motility and visceral sensitivity were assessed. At the end of the study, the mice were euthanized and the blood and colon tissues were collected for analyses. We showed that apremilast treatment significantly ameliorated IBS symptoms in the mice, evidenced by improvement on delayed intestinal motility and visceral hypersensitivity. We found that EGCs were activated in the colon of IBS mice. We then demonstrated that apremilast (10 μM) significantly suppressed TNF-α/IFN-γ stimulated activation of rat EGC cell line CRL-2690 and primary EGCs in vitro, as well as the secretion of EGCs-derived pain mediators and inflammatory factors while ameliorating oxidative stress. These effects depended on the activation of the nuclear factor erythroid 2-related factor 2 (Nrf-2) signaling pathway, which was validated in Nrf-2 knockout EGCs. These results suggest that inhibition of PDE4 by apremilast suppresses EGCs activation by activating the Nrf-2 signaling pathway, leading to decreased expression of pain mediators and inflammatory factors while ameliorating oxidative stress, ultimately alleviating IBS.

Methotrexate (MTX) is frequently administered with the proton pump inhibitor omeprazole (OPZ) to relieve gastrointestinal adverse reactions of MTX, but the coadministration increases the risk of kidney injury. In this study, we investigated the mechanisms of combined OPZ and MTX-induced acute kidney injury (OPZ + MTX-AKI), which was induced in rats or mice by administration of OPZ plus MTX for 14 days. Analysis of the FAERS database revealed that AKI was the principal form of kidney injury when OPZ was administered with MTX. We showed that coadministration of OPZ and MTX to rats resulted in the development of AKI. We found that OPZ and MTX, by inhibiting the expression and activity of SERCA2 and IP3R, respectively, jointly disrupted Ca²⁺ homeostasis, thereby causing cell damage. Transcriptomic analysis of clinical samples revealed that G protein-coupled receptor kinase 2 (GRK2) served as a key protein in OPZ + MTX-AKI. In Grk2^+/- mice and in mice with renal tubular epithelial cell (RTEC)-specific Grk2 knockdown, the manifestations of kidney injury, along with the levels of oxidative stress and apoptosis in the context of OPZ + MTX-AKI, were notably ameliorated. Conversely, in mice with RTEC-specific Grk2 overexpression, the kidney injury was markedly aggravated. Administration of GRK2 inhibitor CP-25 (17.5, 35, 70 mg/kg/d, i.g.) for 14 days dose-dependently alleviated OPZ + MTX-AKI in mice with RTEC-specific Grk2 overexpression. This study elucidates a novel mechanism of AKI induced by the combination of OPZ and MTX and identifies potential therapeutic targets. We provide an essential theoretical foundation for the rational clinical application of OPZ and MTX, as well as for prevention and treatment of the related kidney injury.

Histamine H3 receptor (H3R) and H4 receptor (H4R) are key members of the histamine receptor family, with H3R as a potential target for narcolepsy treatments and H4R as a candidate for next-generation antihistamines for inflammatory and allergic diseases. Although progress has been made in understanding the structure of histamine receptors, the detailed mechanisms of ligand recognition and receptor antagonism for H3R and H4R remain unclear. In this study, using cryo-electron microscopy, we present an inactive structure of H4R bound to a selective antagonist, adriforant, and two Gi-coupled structures of H3R and H4R in complex with histamine. Our structural and mutagenesis analyses provide insights into the selective binding of adriforant to H4R and the recognition of histamine across histamine receptors. Our findings also uncovered distinct antagonistic mechanisms for H3R and H4R and identified the role of aromatic amino acids on extracellular loop 2 in modulating the constitutive activity of H3R and H4R. These findings advance our knowledge of the functional modulation of histamine receptors, providing a foundation for the development of targeted therapeutics for neurological and immune-related disorders.

The global obesity epidemic and its associated metabolic disorders urgently require more effective therapeutic interventions, particularly multi-pathway targeting therapies. Cagrilintide (Cagri), functioning as a dual amylin receptor (AMYRs) and calcitonin receptor (CTR) agonist (DACRA), demonstrates significant efficacy in obesity treatment, although its structural activation mechanism remains unclear. This study elucidates the non-selective activation mechanism by determining cryo-EM structures of Cagri bound to AMY₁R-G_s and CTR-G_s complexes. Cagri adopts similar "bypass" binding modes in both receptors, which is distinct from other existing DACRAs that primarily achieve extended half-life through N-terminal lipid modification. Key molecular features include the F23^Cagri residue anchoring the peptide at the receptor transmembrane (TM) bundle level and the micelle, an E14-R17 intramolecular salt bridge enhancing helical stability, and C-terminal P37^Cagri interaction with the receptor ECD. These features collectively enable non-specific binding and activation across different receptors. Both structural and functional analyses revealed Cagri's non-selective activation of G_s signaling pathways through CTR and AMY₁R. These findings provide a comprehensive structural framework for developing next-generation anti-obesity drugs based on dual receptor activation mechanisms.

Negative-stranded segmented RNA viruses (NSVs) employ a cap-snatching mechanism for transcription, which makes cap-dependent endonuclease (CEN) an attractive target for drug development. Pathogenic arenaviruses pose a serious threat to humans, yet no approved treatments exist, underscoring the importance of discovering novel compounds targeting arenaviral CENs. Therefore, this study aimed to identify novel CEN inhibitors for arenaviruses and investigate their antiviral mechanisms. A high-throughput screening system based on enzymatic activity of CEN was established for discovering inhibitors of lymphocytic choriomeningitis virus (LCMV). Several hit compounds were screened from a vast natural product library, and then evaluated for both toxicity and inhibition through cellular and animal experiments. One candidate compound was finally identified, and its mechanism of action on CEN was elucidated through simulation analysis and biochemical studies. Moreover, its broad-spectrum effects were investigated among pathogenic arenaviruses as well as representative NSVs. Consequently, salvianolic acid A (SAA) from Salvia miltiorrhiza was identified as a promising compound that effectively inhibited LCMV infection and significantly reduced the viral load via intravenous administration. It was shown to bind to the active pocket of arenaviral CENs while chelating their metal ions through its acid carboxyl group, acting in a substrate-competitive manner. Additionally, SAA exhibited broad-spectrum inhibition of pathogenic arenaviruses as well as representative viruses from the order Bunyavirales. This study identified SAA as a novel CEN inhibitor, particularly for pathogenic arenaviruses, showcasing its promise for antiviral drug development.

Parkinson's disease (PD) involves α-synuclein (αSyn) oligomerization and aggregation, processes facilitated by glycosphingolipids. Defective glycosphingolipid transport and degradation-especially via the lipid-degrading enzyme glucocerebrosidase 1 (GCase, gene GBA1)-aggravate PD and increase dementia risk. Ambroxol is a mucolytic drug and has emerged as a promising add-on therapy for PD since it acts as a chaperone for misfolded GCase, thereby increases the likelihood that mutated and misfolded GCase eludes ER-associated degradation (ERAD) and is transported to its destination, the lysosome. In this study we investigated whether and how ambroxol provided therapeutic benefits for PD irrespective of the GBA1 mutation status. Pink1^-/-/SNCA^A53T double mutant PD mice were administered ambroxol either via the drinking water (120-150 mg·kg^-1·d^-1) or via food pellets (75-100 mg·kg^-1·d^-1) for approximately 6 months. During the treatments mice were observed in IntelliCages; and in motor, sensory and cognitive functions tests. After mice were euthanized, tissues were dissected for protein, lipidomic and metabolomic analyses. We showed that high-dose long-term ambroxol was well tolerated and led to mild behavioral and metabolic improvements but had adverse effects on brain sulfatides, lysosomal functions and mitochondrial cardiolipins. Notably, brain levels of glucosylceramides (GlcCer 16:0) were normalized, while sulfatides (SHexCer) further increased. Western blots revealed a modest reduction of αSyn and phosphorylated αSyn (P-Ser129). IntelliCage assessments showed increased exploratory activity with ambroxol, suggesting reduced bradykinesia, though sensory and motor functions remained unchanged. Lipidomic profiles of mitochondria showed accumulation of HexCer and triglycerides in PD mitochondria, regardless of treatment, while ambroxol led to an additional decline of cardiolipins including the most abundant tetralinoleoyl cardiolipins. In HT22 hippocampal neurons preloaded with αSyn pre-formed fibrils, ambroxol accumulated within lysosomes, increased lysosomal mass and sphingolipid content and promoted lysosomal enzyme release. Collectively, these results suggest that ambroxol confers transient behavioral benefits and modestly reduces αSyn pathology, albeit with potential drawbacks. In addition, its lysosomal accumulation may further disrupt sphingolipid metabolism and impair mitochondrial compensatory mechanisms. Ambroxol-induced lysosomal exocytosis may transiently relieve αSyn burden, but further interventions would be required to ensure αSyn clearance from the brain.

For several decades, the glutamate delta-1 receptor (GluD1) has remained an enigmatic entity among ionotropic glutamate receptors (iGluRs), primarily due to its lack of classical ion channel activity. Recent advancements have redefined GluD1 as a multifunctional synaptic organizer, essential for the development, plasticity, and behavioral regulation of both excitatory and inhibitory circuits. In this review, we synthesize recent progress at the structural, molecular, and circuit levels to reconceptualize GluD1 as a pivotal signaling scaffold that functions through non-ionotropic mechanisms. We emphasize the modular architecture of GluD1, encompassing the amino-terminal domain, ligand-binding domain, transmembrane region, and C-terminal domain to elucidate how each component uniquely contributes to synaptic function. Evidence from genetic models and structural biology underscores GluD1's involvement in transsynaptic adhesion, ligand-dependent conformational signaling, and intracellular pathway modulation. Additionally, we discuss its emerging clinical significance, with GRID1 mutations associated with neurodevelopmental and psychiatric disorders, and recent findings implicating GluD1 dysfunction in chronic pain. Finally, we explore domain-specific therapeutic strategies, including peptide mimetics, synthetic organizers, and non-ionotropic modulators, positioning GluD1 as a promising target for circuit-level intervention in brain disorders.

Peptide-drug conjugate (PDC) represents a special therapeutic strategy to enhance drug delivery by targeting tumor cell receptors while minimizing off-target effects. Comparing the antibody-drug conjugate (ADC), the targeting peptide constitutes the pivotal component of PDC, especially with easy optimization of peptides to promote their in vivo stability, and with the agonist stimulated GPCR internalization to facilitate drug distribution into tumor cell plasma. Herein, we have optimized a highly stable peptide molecule LanTC targeting somatostatin receptor 2 (SSTR2), through amino acid substitution and disulfide bond modification from an FDA proved peptide drug Lanreotide. The LanTC based PDC was constructed through conjugation of the cytotoxic drug emtansine (DM1). The LanTC-DM1 PDC exhibited high stability and high agonist affinity to SSTR2. Subsequent in vitro and in vivo pharmacological data revealed that LanTC-DM1 PDC exhibited antitumor activity in small cell lung cancers (SCLC) which was known to have over-expressing SSTR2. The LanTC-DM1 PDC with specific targeting and antitumor activity provides a solid basis not only for advancing SSTR2-targeted PDCs as a promising therapy for SCLC, but also for other PDC developments targeting GPCRs in plasma membrane of tumor cells.

Cancer metastasis and drug resistance are intricately linked processes that drive cancer progression and poor prognosis. One of the hallmarks of cancer is metabolic reprogramming, which evolves at various stages of tumor metastasis and drug resistance progression. This reprogramming involves the dysregulation of metabolic enzymes, which not only regulate the metabolic status in cancer cells, but also play multifunctional roles through influencing downstream signaling networks, acting as protein kinases, post-translational modifications and multiple biological processes, thereby exacerbating cancer malignancy. This review focuses on the metabolic enzyme-associated protein-protein interactions (mPPIs) during tumor metastasis and therapeutic resistance, and discusses the roles of key enzymes in glycolysis, the serine synthesis pathway, the pentose phosphate pathway, the glucuronate pathway and the sorbitol pathway. Understanding the distinct multifunctionality of these metabolic enzymes is crucial for gaining valuable insights into cancer pathogenesis and identifying potential therapeutic vulnerability to combat metastatic progression and overcome therapy resistance.