Search Results (793)

The glucagon-like peptide-1 receptor (GLP-1R), which belongs to the class B1 G protein-coupled receptor (GPCR) family, is an important target for treatment of metabolic disorders, including type 2 diabetes and obesity. The growing interest in GLP-1R-based therapies is driven by the development of various functional agonists as well as the huge commercial market. Thus, understanding the structural details of ligand-induced signaling are important for developing improved GLP-1R drugs. Here, we investigated the conformational dynamics of the receptor in complex with a selection of prototypical functional agonists, including CHU-128 (small molecule-biased), danuglipron (small molecule balanced), and Peptide 19 (peptide balanced), which exhibit unique, distinct binding modes and induced helix packing. Furthermore, our all-atom molecular dynamics (MD) simulations revealed atomic feature how different those ligands led to signaling pathway preference. Our findings offer valuable insights into the mechanistic principle of GLP-1R activation, which are helpful for the rational design of next-generation GLP-1R drug molecules. 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

When non-functioning pituitary adenomas (NFPAs) behave aggressively or recur after first-line surgical treatment, it can be challenging to decide whether and how to escalate therapy. Up to 47% of patients with residual tumor after transsphenoidal surgery will show disease recurrence or progression and may require an intervention. Repeat surgical resection can be attempted in select cases if the tumor is accessible; for the remainder of patients, non-surgical treatment options may need to be considered. Radiotherapy can control tumor growth in 75% of NFPAs, but confers increased risk of hypopituitarism and other disorders. Currently, there are no medical therapies approved for patients with recurrent or aggressive NFPA. However, several have been investigated, including temozolomide, somatostatin receptor ligands, dopamine agonists, immune checkpoint inhibitors, vascular endothelial growth factor inhibitors, and peptide receptor radionuclide therapy. We present a review of the available evidence to provide guidance for pituitary endocrinologists and neuro-oncologists when treating patients with recurrent or aggressive NFPA. Full article

TREM2 (triggering receptor expressed on myeloid cells 2) is a membrane-bound receptor primarily expressed on microglia in the central nervous system (CNS). TREM2 plays a crucial role in regulating immune responses, phagocytosis, lipid metabolism, and inflammation. Mutations in the TREM2 gene have been linked to various neurodegenerative diseases, including Alzheimer’s disease (AD), frontotemporal dementia (FTD), Parkinson’s disease (PD), and Nasu–Hakola disease (NHD). These mutations are suggested to impair microglial activation and reduce the ability to clear amyloid aggregates, leading to exacerbated neuroinflammatory responses and accelerating disease progression. This review provides an overview of TREM2 structure, functions, and known pathogenic variants—including Arg47His, Arg62His, His157Tyr, Tyr38Cys, and Thr66Met. Furthermore, the molecular and cellular consequences of TREM2 mutations are introduced, such as impaired ligand binding, altered protein folding and trafficking, enhanced TREM2 shedding, and dysregulated inflammatory signaling. We also highlight recent advances in therapeutic strategies aimed at modulating TREM2 signaling. These include monoclonal antibodies (e.g., AL002, CGX101), small molecule agonists, and gene/cell-based therapies that seek to restore microglial homeostasis, enhance phagocytosis, and reduce neuroinflammation. While these approaches show promise in in vivo/in vitro studies, their clinical translation may be challenged by disease heterogeneity and mutation-specific responses. Additionally, determining the appropriate timing and precise dosing will be essential. Full article

Oral squamous cell carcinoma (OSCC) is a prevalent and aggressive malignancy with poor prognosis, largely due to its high metastatic potential and resistance to conventional therapies. Recent advances in cancer biology have underscored the significance of regulated cell death pathways, including apoptosis, autophagic cell death (ACD), necroptosis, pyroptosis, and ferroptosis, in modulating tumor progression and therapeutic responses. This review provides the current insights into the molecular mechanisms underlying these cell death pathways and explores their therapeutic relevance in OSCC. Restoration of apoptosis using BH3 mimetics, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptor agonists, and p53 reactivators shows promise for sensitizing OSCC cells to treatment. Autophagy plays context-dependent roles in cancer, acting as a tumor suppressor during early carcinogenesis by maintaining cellular homeostasis, and as a tumor promoter in established tumors by supporting cancer cell survival under stress. Targeting necroptosis and pyroptosis has emerged as a novel strategy for inducing cancer cell death, with compounds such as acetylshikonin and okanin demonstrating antitumor effects. Additionally, the induction of ferroptosis via lipid peroxidation and glutathione peroxidase 4 (GPX4) inhibition offers a promising avenue for overcoming drug resistance, with agents such as quercetin and trifluoperazine exhibiting preclinical success. Integration of these therapeutic approaches may enhance the OSCC treatment efficacy, reduce chemoresistance, and provide novel prognostic biomarkers for clinical management. Future studies should focus on optimizing combinatorial strategies that effectively leverage these pathways to improve OSCC patient outcomes. Full article

Neuropeptide FF (NPFF) receptor antagonists prevent morphine-mediated antinociceptive tolerance, and compounds with dual mu opioid receptor (MOR) agonist and NPFF antagonist activity produce antinociception without tolerance. Compounds synthesized showed affinities in radioligand competition binding assays in the nM and µM range at the opioid and NPFF receptors, respectively, and displayed substitution-dependent functional profiles in the [³⁵S]GTPγS functional assay. From six compounds screened in vivo for antinociception and ability to prevent NPFF-induced hyperalgesia in mouse warm water tail withdrawal tests, compound 22b produced dose-dependent MOR-mediated antinociception with an ED₅₀ value (and 95% confidence interval) of 6.88 (4.71–9.47) nmol, i.c.v., and also prevented NPFF-induced hyperalgesia. Meanwhile, 22b did not demonstrate the respiratory depression, hyperlocomotion, or impaired intestinal transit of morphine. Moreover, repeated treatment with 22b produced a 1.6-fold rightward shift in antinociceptive dose response, significantly less acute antinociceptive tolerance than morphine. Evaluated for microsomal stability in vitro and in vivo pharmacokinetic profile, 22b showed suitable microsomal stability paired in vivo with a large apparent volume of distribution and a clearance smaller than the hepatic flow in rats, suggesting no extra-hepatic metabolism. In conclusion, the present study confirms that dual-action opioid–NPFF ligands may offer therapeutic promise as analgesics with fewer liabilities of use. Full article

The development of orally bioavailable non-peptidomimetic glucagon-like peptide-1 receptor agonists (GLP-1RAs) offers a promising therapeutic avenue for the treatment of type 2 diabetes mellitus (T2DM) and obesity. An extensive in silico approach combining structure-based drug design and ligand-based strategies together with pharmacokinetic properties and drug-likeness predictions is implemented to identify novel non-peptidic GLP-1RAs from the COCONUT and Marine Natural Products (CMNPD) libraries. More than 700,000 compounds were screened by shape-based similarity filtering in combination with precision docking against the orthosteric site of the GLP-1 receptor (PDB ID: 6X1A). The docked candidates were further assessed with the molecular mechanics MM-GBSA tool to check the binding affinities; the final list of candidates was validated by running a 500 ns long MD simulation. Twenty final hits were identified, ten from each database. The hits contained compounds with reported antidiabetic effects but with no evidence of GLP-1 agonist activity, including hits 1, 6, 7, and 10. These findings proposed a novel mechanism for these hits through GLP-1 activity and positioned the other hits as potential promising scaffolds. Among the studied compounds—especially hits 1, 5, and 9—possessed strong and stable interactions with critical amino acid residues such as TRP-203, PHE-381, and GLN-221 at the active site of the 6X1A-substrate along with favorable pharmacokinetic profiles. Moreover, the RMSF and RMSD plots further suggested the possibility of stable interactions. Specifically, hit 9 possessed the best docking score with a ΔG_bind value of −102.78 kcal/mol, surpassing even the control compound in binding affinity. The ADMET profiling also showed desirable drug-likeness and pharmacokinetic characteristics for hit 9. The pipeline of computational integration underscores the potential of non-peptidic alternatives in natural product libraries to pursue GLP-1-mediated metabolic therapy into advanced preclinical validation. Full article

Clinically nonfunctioning pituitary tumors (CNFPTs) typically do not cause hormonal excess, progress insidiously, and are often large and invasive at presentation. Complete resection is frequently not attainable; radiotherapy (RT) may effectively limit growth but carries a significant risk of hypopituitarism. Medical therapy with dopamine D2 receptor agonists and/or somatostatin analogs has been explored in CNFPTs but have yielded inconsistent results, and there is an unmet need for novel efficacious and safe medical therapies. The authors used the PubMed database to identify and review articles published from January 1982 to July 2024, that discussed the medical treatment of CNFPTs. The most commonly studied medical therapies were somatostatin receptor ligands (SRLs) and dopamine D2 receptor agonists. Of 111 patients with CNFPTs treated with SRLs, 31 (28%) exhibited tumor shrinkage. Following dopamine agonist treatment in 355 patients, tumor shrinkage occurred in 113 (32%), tumor stabilization in 182 (51%), and tumor growth in 60 (17%). The efficacy of other less commonly employed therapies such as GnRH analogs, PRRT, and temozolomide was also reviewed. Efficacious and safe medical therapies evaluated in robust randomized placebo-controlled clinical trials are needed to improve the management of CNFPTs. Full article

TRPA1 (Transient Receptor Potential Ankyrin 1), a cation channel predominantly expressed in sensory neurons, plays a critical role in detecting noxious stimuli and mediating pain signal transmission. As a key player in nociceptive signaling pathways, TRPA1 has emerged as a promising therapeutic target for the development of novel analgesics. Crotalphine (CRP), a 14-amino acid peptide, has been demonstrated to specifically activate TRPA1 and elicit potent analgesic effects. Previous cryo-EM (cryo-electron microscopy) studies have elucidated the structural mechanisms of TRPA1 activation by small-molecule agonists, such as iodoacetamide (IA), through covalent modification of N-terminal cysteine residues. However, the molecular interactions between TRPA1 and peptide ligands, including crotalphine, remain unclear. Here, we present the cryo-EM structure of ligand-free human TRPA1 consistent with the literature, as well as TRPA1 complexed with crotalphine, with resolutions of 3.1 Å and 3.8 Å, respectively. Through a combination of single-particle cryo-EM studies, patch-clamp electrophysiology, and microscale thermophoresis (MST), we have identified the cysteine residue at position 621 (Cys621) within the TRPA1 ion channel as the primary binding site for crotalphine. Upon binding to the reactive pocket containing C621, crotalphine induces rotational and translational movements of the transmembrane domain. This allosteric modulation coordinately dilates both the upper and lower gates, facilitating ion permeation. Full article

The active form of vitamin D₃, 1α,25-dihydroxyvitamin D₃ (1,25D₃), regulates a number of physiological and pathological processes, including cell proliferation and differentiation. Thousands of analogues of 1,25D₃ have been developed with the aim of selective effects for medical use. Here we describe the synthesis of two new unconventional vitamin D analogues bearing A-ring modifications with ortho-carborane (dicarba-o-closo-1,2-dodecaborane) units. The ligands function as agonists for VDR with similar antiproliferative activities as 1,25D₃. Whereas mice treated with the analogues 4 and 5 exhibited similar hypercalcemic activities as 1,25D₃, only compound 4 and 1,25D₃ induced the strong activation of CYP24A1 mRNA expression but not compound 5. Full article

Recent bioassay studies have unexpectedly supported the high (computationally predicted) binding affinities of angiotensin receptor blockers (ARBs) at α-adrenergic receptors (αARs) in isolated smooth muscle. Computational predictions from ligand docking studies are consistent with very low concentrations of ARBs (e.g., sartans or bisartans) that partially reduce (20–50%) the contractile response to phenylephrine, suggesting that some ARBs may function as partial inverse agonists at αARs. Virtual ligand screening (docking) and molecular dynamics (MD) simulations were carried out to explore the binding affinities and stabilities of selected non-peptide ligands (e.g., ARBs and small-molecule opioids) for several G-protein coupled receptor (GPCR) types, including angiotensin II (AngII) type 1 receptor (AT₁R), α1AR, α2AR, and μ-(µOR) and ժ-opioid receptors (ժOR). Results: All ligands docked preferentially to the binding pocket on the cell surface domain of the GPCR types investigated. Drug binding was characterized by weak interactions (hydrophobic, hydrogen bonding, pi-pi) and stronger ionic and salt-bridge interactions (cation-pi and cation-anion interactions). Ligands specific to each GPCR category showed considerable cross-binding with alternative GPCRs, with small-molecule medications appearing less selective than their peptide or ARB functional equivalents. ARBs that exhibit higher affinities for AT₁R also demonstrate higher affinities for µORs and ժORs than opiate ligands, such as fentanyl and naltrexone. Moreover, ARBs had a higher affinity for αARs than either alpha agonists (epinephrine and phenylephrine) or inhibitors (prazosin and doxazosin). MD simulations of membrane-embedded ARB-GPCR complexes proved stable over nanosecond time scales and suggested that some ARBs may behave as agonists or antagonists depending on the GPCR type. Based on the results presented in this and related investigations, we propose that agonists bind to the resting A-site of GPCRs, while inverse agonists occupy the desensitizing D-site, which partial agonists like morphine and fentanyl share, contributing to addiction. ARBs block both AngII and alpha receptors, suggesting that they are more potent antihypertensive drugs than ACE inhibitors. ARBs have the potential to inhibit morphine tolerance and appear to disrupt receptor desensitization processes, potentially by competing at the D-site. Our results suggest the possible therapeutic potential of ARBs in treating methamphetamine and opiate addictions. Full article

Background: Glucocorticoid insensitivity is a problem for the therapy of chronic inflammatory lung diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Both are non-communicable chronic inflammatory lung diseases with worldwide increasing incidences. Only symptoms can be controlled by inhaled or systemic glucocorticoids, often combined with β2 agonists and/or muscarinic receptor antagonists. The therapeutic effect of glucocorticoids varies between individuals, and a significant number of patients do not respond well. It is believed that only protein-free circulating unbound glucocorticoids can enter cells by diffusion and achieve their therapeutic effect by binding to the intracellular glucocorticoid receptor (GR), encoded by the NR3C1 gene, for which over 3000 single-nucleotide polymorphisms have been described. In addition, various GR protein isoforms result from 11 transcription start sites, and differential mRNA splicing leads to further GR protein variants; each can be modified post-translational and alter steroid response. To add more variety, some GR isoforms are expressed cell-type specific or in a sub-cellular location. The GR only functions when it forms a complex with other intracellular proteins that regulate ligand binding, cytosol-to-nuclear transport, and nuclear and cytosolic action. Importantly, the timing of the GR activity can be cell type, time, and condition specific. These factors are rarely considered when assessing disease-specific loss or reduced GR response. Conclusions: Future studies should analyze the timing of the availability, activity, and interaction of all components of the glucocorticoid signaling cascade(s) and compare these factors between non-diseased and diseased probands, applying the combination of all omics methods (250). Full article

Background/Objectives: Disruptions in adipose tissue dynamics contribute to obesity-related metabolic disorders, emphasizing the need for targeted therapies focusing on adipose tissue cells, including progenitor cells and adipocytes. Peroxisome proliferator-activated receptor gamma (PPARG) ligands are potent insulin sensitizers used in type 2 diabetes treatment. This study investigated the effects of rosiglitazone, a PPARG agonist, and betulinic acid, a PPARG antagonist, on adipogenesis and apoptosis in 3T3-L1 pre-adipocytes. Method: 3T3-L1 pre-adipocytes were treated with rosiglitazone or betulinic acid during adipogenic differentiation. Lipid droplet formation was used to evaluate adipogenesis. Cell growth and cell death were assessed using the resazurin-based cell viability assay, trypan blue exclusion assay, LDH assay, and Annexin V/PI staining. Quantitative PCR was conducted to examine the expression of genes associated with adipogenesis and apoptosis. Results: Betulinic acid reduced adipogenesis only when administered daily for eight days. Rosiglitazone did not alter the overall lipid quantity; however, it promoted a shift toward fewer but larger lipid droplets. Both compounds increased Adipoq and Cfd expression, and betulinic acid also elevated Fabp4. Rosiglitazone induced stronger cell aggregation. Despite increased cell death, overall viability was maintained. Apoptotic cell death was enhanced by both compounds and confirmed via Annexin V/PI staining and flow cytometry, accompanied by downregulation of Ccnd1 and Bcl2. Additionally, rosiglitazone markedly increased the expression of Cebpa, a key regulator that can modulate lipid droplet formation and the balance between cell growth and death. Conclusions: Rosiglitazone and betulinic acid differentially modulate adipogenesis and apoptosis in 3T3-L1 cells, revealing a complex interplay between lipid accumulation and programmed cell death. Together, the findings underscore the potential of dual PPARG-targeting approaches for metabolic disease interventions. Full article

CB₁ and CB₂ cannabinoid receptors are members of the GPCR superfamily that modulate the effects of endocannabinoids. CB₁ is the most abundant CB receptor in the central nervous system, while CB₂ is present both peripherally and in the brain. CB₂ plays a role in inflammation, as well as neurodegenerative and psychiatric disorders. To identify new ligands for CB₂, we screened a library of FDA-approved drugs for activity at the receptor using a thallium flux assay, resulting in the discovery of the immunosuppressant mycophenolate mofetil as a potent, selective activator of CB₂. Further characterization of the compound confirmed agonist activity in a variety of complementary assays, including PI hydrolysis, cAMP inhibition, and β-arrestin recruitment. Radioligand binding assays established a non-competitive interaction with the site occupied by [³H]CP55,940. CB₂ agonists GW-842,166X and MDA7 were also profiled, revealing that GW-842,166X exhibits a similar activity profile to mycophenolate mofetil, whereas MDA7 presents a distinct profile. These differences provide insight into the complex CB₂ pharmacology impacting preclinical and clinical studies, and ultimately, new treatment strategies for brain disorders. Full article

The kisspeptin/kisspeptin receptor (KISS1/KISS1R) system has emerged as a vital regulator of various physiological processes, including cancer progression, metabolic function, and reproduction. KISS1R, a member of the G protein-coupled receptor family, is crucial for regulating the hypothalamic/pituitary/gonadal axis. A growing number of KISS1R agonists are currently being investigated in clinical trials, whereas the number of antagonists remains limited. Most existing ligands are synthetic peptides, with only a few small-molecule compounds, such as musk ambrette, having been identified. In this article, we provide an overview of the KISS1/KISS1R system and its involvement in diseases such as reproductive disorders, cancer, diabetes, and cardiovascular disease. We also highlight the various technologies used to identify KISS1R ligands, including radioligand binding assays, calcium flux assays, IP1 formation assays, ERK phosphorylation assays, qRT-PCR, and AI-based virtual screening. Furthermore, we discuss the latest advances in identifying KISS1R agonists and antagonists, highlighting ongoing challenges and future directions in research. These insights lay the groundwork for future research aimed at leveraging this system for developing innovative therapeutic strategies across a range of medical conditions. Full article