Synovial tissue infiltration by pro-inflammatory macrophages is a critical factor in the pathogenesis of rheumatoid arthritis (RA), correlating strongly with high disease activity scores in affected joints and often lead to progressive joint damage and disability. Methotrexate (MTX) is the frontline therapeutic drug for RA, but its efficacy is hampered by short plasma half-life, reduced bioavailability, and severe adverse effects. To address these limitations, we developed an injectable polymer-nanomedicine supramolecular hydrogel (PNSH) with dynamic mechanical properties and morphology tailored for intra-articular administration and sustained drug release with minimized off-target toxicity. The hydrogel was assembled from MTX-loaded polymeric nanoparticles chemically conjugated with partially oxidized glucomannan. In vitro and in vivo studies demonstrate that PNSH exhibits low cytotoxicity and superior biocompatibility. It supports the sustained release of MTX, which promotes M1 macrophage remodeling towards the M2 macrophage via switching IRF5 and IRF8 to IRF3 and IRF4 through the adenosine A2A receptor (A2AR) signaling pathway. In a rat arthritis model, PNSH effectively mitigated tissue-damaging inflammation and restored the articular immune homeostasis, thereby inhibiting arthritis progression. Notably, PNSH also upregulated CD73 and A2AR, key components of the extracellular purinergic signaling pathway, promoted the transcriptional expression of IRF3 and IRF4, and significantly decreased the transcriptional expression of IRF5 and IRF8, driving macrophage re-polarization towards M2 phenotype. These findings suggest that PNSH has the potential to serve as a novel drug delivery system for regulating inflammation and treating RA.
© 2025 The Authors.

G protein-coupled receptors (GPCRs) are major drug targets and key regulators of cell signaling. The basis of functional diversification between individual GPCRs and families of GPCRs can be revealed by investigating evolutionary conservation patterns. In this study, we investigated the functional role of specifically conserved residues in the TM1/TM7/H8 dimerization interface of beta-adrenergic receptors (BARs). Residues specifically conserved for B2AR compared to B1AR and B3AR subtypes were identified via phylogenetic analysis. The significance of residues differentially conserved between receptor subtypes at the TM1/TM1 interface was investigated using molecular dynamics (MD) simulations in combination with biophysical and functional studies. Our findings suggest that differentially conserved residues within TM1 of BARs modulate receptor conformation without disrupting dimerization to impact cell surface expression, basal activity, and endocytosis. This highlights the importance of TM1 in modulating receptor function and provides new insights into the evolutionary and functional differences among beta-adrenergic receptor subtypes.
© 2026 The Authors.

Phosphodiesterase-4B (PDE4B) regulates intracellular cAMP and drives pro-inflammatory cytokine production. Novel small-molecule PDE4B inhibitors with improved isoform selectivity are needed to broaden therapeutic options. We report the discovery and validation of SIP0401, a ChemBridge-derived small molecule prioritized via an integrated in silico pipeline combining pharmacophore modeling, molecular docking, and dynamics-based scoring.
SIP0401 was identified through virtual screening and ligand efficiency-guided filtering against the PDE4B catalytic domain. Experimental profiling included PDE-Glo™, HTRF cAMP, and differential scanning fluorimetry (DSF) with recombinant human PDE4B. Isoform preference (PDE4A/C/D) was assessed by PDE-Glo™. Aggregation, solubility, and luciferase interference were evaluated. Cellular assays included cAMP (HTRF) and TNF-α ELISA in THP-1 macrophages, and cytotoxicity (MTT) in BEAS-2B cells. Curve fitting used GraphPad Prism.
SIP0401 showed high predicted binding affinity (ΔG = - 8.6 kcal/mol) and favorable interaction stability in dynamics. It inhibited PDE4B with IC₅₀ = 282 nM (PDE-Glo) and 338.4 nM (HTRF); rolipram controls gave 91.5 nM and 106.6 nM. DSF showed Tₘ shift + 4.2 °C; luciferase interference was ≤ 6%. SIP0401 was selective for PDE4B over PDE4A/C/D (IC₅₀s 1.16-1.97 µM; 5.3-7.0×). In THP-1 cells, SIP0401 increased cAMP (EC₅₀ = 2.52 µM) and inhibited TNF-α (IC₅₀ = 3.24 µM). BEAS-2B viability > 90% up to 50 µM.
SIP0401, identified by structure-guided virtual screening, demonstrated moderate biochemical preference for PDE4B over other PDE4 isoforms under the tested conditions. Additionally, the observed cellular activity and favorable colloidal/solubility profiles supports its further optimization and in vivo assessment.
© 2026. The Author(s), under exclusive licence to Springer Nature B.V.

Hyperkinetic movement disorders, like dystonia, chorea, myoclonus, dyskinesia, and tremor, can be extremely disabling, impairing quality of life. Our translational approach in humans and mice investigates the link between cyclic AMP (cAMP) signaling pathway alterations in striatal neurons and hyperkinetic movement disorders. ADCY5 encodes adenylyl cyclase 5, key enzyme for striatal cAMP synthesis. Pathogenic variants result in mixed hyperkinetic movement disorders (MxMD-ADCY5). We prove caffeine therapeutic effect in a prospective trial in two patients with MxMD-ADCY5 and generated an Adcy5 R419W mouse model harboring the most frequent human pathogenic variant to understand underlying mechanisms. In patients, movements' severity is increased in absence of caffeine. In mice, caffeine improves motor symptoms through adenosine A2A receptor blockade. Mutation increases cAMP signaling in striatal projection neurons, an effect selectively corrected by A2A receptor antagonism in indirect pathway neurons. Fine modulation of neuronal cAMP levels represents a key target to treat hyperkinetic disorders, especially dystonia/dyskinesia.
© 2025 The Authors.

The mechanism underlying the crosstalk between Gαq-coupled bombesin receptor subtype-3 (BRS3) and Gαi-coupled E-prostanoid 3 receptor (EP3) remains unknown. Here, we report that BRS3 and EP3 form dimers in the membrane of living HEK-293T cells. BRS3-EP3 dimers switched to couple Gαs protein upon PGE2 stimulation, which provoked cAMP accumulation and enhanced P38 phosphorylation. Quantitative proteomics analysis revealed that the activation of BRS3-EP3 dimers was associated with cell migration. B16 melanoma cell line, which endogenously expresses BRS3 and EP3, was selected to investigate the function of BRS3-EP3 dimers. The results demonstrated that the presence of BRS3 inhibited the migration of B16 melanoma cells upon PGE2 stimulation. Utilizing inhibitors of Gαs and P38, we found that BRS3 interacted with EP3 and switched to couple Gαs protein, causing P38 phosphorylation to inhibit F-actin rearrangement and ultimately suppressed cell migration. Our study reveals the crosstalk between the orphan receptor BRS3 and EP3, and provides a potential novel target for disease treatment.
© 2024 The Authors.