Biology subjects

Sepe, V.

Publications and source records attributed to Sepe, V..

5 recordsLinked to original sources

bioRxiv2026

From Structure to Dynamics: Activation Mechanism of the G Protein-Coupled Bile Acid Receptor 1-Gs Complex

The G protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5) is a key mediator of bile acid signaling, exerting its physiological effects through coupling with the stimulatory G protein (Gs). This interaction is essential for stabilizing the receptors active conformation and triggering downstream signaling. Among endogenous ligands, lithocholic acid (LCA) is the most potent natural agonist. However, the dynamic features underlying its binding and activation mechanisms remain poorly defined. In this study, we investigated the molecular basis of the interaction between LCA and GPBAR1, as well as the functional consequences of this interaction on receptor activation by integrating homology modelling, molecular docking, and molecular dynamics (MD) simulations. Our calculations reveal that LCA binding stabilizes the active state of GPBAR1, biasing the conformational ensemble of TM5 and TM6, as well as the main microswitches. These ligand-induced rearrangements enhance the coupling interface with the 5 helix of Gs and facilitate allosteric communication between the orthosteric and intracellular sites. Overall, our findings provide dynamic insight into how LCA modulates GPBAR1 activation and G protein engagement, highlighting its role as a molecular effector in bile acid signaling, and furnishing molecular detail relevant to ongoing efforts in GPBAR1-targeted compound development.

bioinformatics↗

bioRxiv2024

A microbial derived bile acid acts as GPBAR1 agonist and RORγt inverse agonist and reverses inflammation in inflammatory bowel disease

The interplay between the dysbiotic microbiota and bile acids is a critical determinant for development of a dysregulated immune system in inflammatory bowel disease (IBD). Here we have investigated the fecal bile acid metabolome, gut microbiota composition, and immune responses in IBD patients and murine models of colitis and found that IBD associates with an elevated excretion of primary bile acids while secondary, allo- and oxo- bile acids were reduced in both human and mice models of IBD. These changes correlated with the disease severity, mucosal expression of pro-inflammatory cytokines and chemokines, and reduced inflow of anti-inflammatory macrophages and Treg in the gut. Analysis of bile acids metabolome in the feces allowed the identification of five bile acids: 3-oxo-DCA, 3-oxo-LCA, allo-LCA, iso-allo-LCA and 3-oxo-UDCA, whose excretion was selectively decreased in IBD patients and diseased mice. By transactivation assay and docking calculations all five bile acids were shown to act as GPBAR1 agonists and ROR{gamma}t inverse agonists, skewing Th17/Treg ratio and macrophage polarization toward an M2 phenotype. In a murine model of colitis, administration of 3-oxo-DCA suffices to reverse colitis development and intestinal dysbiosis in a GPBAR1-dependent manner. In vivo administration of 3-oxo-DCA to colitic mice also reserves disease severity and ROR{gamma}t activation induced by a ROR{gamma}t agonist and IL-23, a Th17 inducing cytokine. These results demonstrated intestinal excretion of 3-oxoDCA, a dual GPBAR1 agonist and ROR{gamma}t inverse agonist, is reduced in IBD and models of colitis and its restitution protects against colitis development, highlighting a potential role for this agent in IBD management.

immunology↗

bioRxiv2023

Bile Acids Serve As Endogenous Antagonists Of The Leukemia Inhibitory Factor (LIF) Receptor in Oncogenesis

The leukemia inhibitory factor (LIF) is member of IL-6 family of cytokines involved immune regulation, morphogenesis and oncogenesis. In cancer tissues, LIF binds a heterodimeric receptor (LIFR), formed by a LIFR{beta} subunit and glycoprotein(gp)130, promoting epithelial mesenchymal transition and cell growth. Bile acids are cholesterol metabolites generated at the interface of host metabolism and the intestinal microbiota. Here we demonstrated that bile acids serve as endogenous antagonist to LIFR in oncogenesis. The tissue characterization of bile acids content in non-cancer and cancer biopsy pairs from gastric adenocarcinomas (GC) demonstrated that bile acids accumulate within cancer tissues, with glyco-deoxycholic acid (GDCA) functioning as negative regulator of LIFR expression. In patient-derived organoids (hPDOs) from GC patients, GDCA reverses LIF-induced stemness and proliferation. In summary, we have identified the secondary bile acids as the first endogenous antagonist to LIFR supporting a development of bile acid-based therapies in LIF-mediated oncogenesis.

cancer biology↗

bioRxiv2021

Analysis of gastric cancer transcriptome allows the identification of histotype specific molecular signatures with prognostic potential

Gastric cancer is the fifth most common malignancy but the third leading cause of cancer-associated mortality worldwide. Therapy for gastric cancer remain largely suboptimal making the identification of novel therapeutic targets an urgent medical need. In the present study we have carried out a high-throughput sequencing of transcriptome expression in patients with gastric cancers. Twenty-four patients, among a series of 53, who underwent an attempt of curative surgery for gastric cancers in a single center, were enrolled. Patients were sub-grouped according to their histopathology into diffuse and intestinal types, and the transcriptome of the two subgroups assessed by RNAseq analysis and compared to the normal gastric mucosa. The results of this investigation demonstrated that the two histopathology phenotypes express two different patterns of gene expression. A total of 2064 transcripts were differentially expressed between neoplastic and non neoplastic tissues: 772 were specific for the intestinal type and 407 for the diffuse type. Only 885 transcripts were simultaneously differentially expressed by both tumors. The per pathway analysis demonstrated an enrichment of extracellular matrix and immune dysfunction in the intestinal type including CXCR2, CXCR1, FPR2, CARD14, EFNA2, AQ9, TRIP13, KLK11 and GHRL. At the univariate analysis reduced levels AQP9 was found to be a negative predictor of 4 years survival. In the diffuse type low levels CXCR2 and high levels of CARD14 mRNA were negative predictors of 4 years survival. In summary, we have identified a group of genes differentially regulated in the intestinal and diffuse histo-types of gastric cancers with AQP9, CARD14 and CXCR2 impacting on patients prognosis, although CXCR2 is the only factor independently impacting overall survival. Simple summaryGastric cancer is the fifth most common malignancy and the third leading cause of cancer-associated mortality worldwide. Although several new pharmacological approaches are currently developed, surgery remains the unique valid option of treatment but survival remains very poor over the last decades. Therefore, understanding the underlying molecular mechanisms of the gastric carcinogenesis and identifying sensitive biomarkers could be helpful for the prevention and treatment of the disease. Currently, the high-throughput sequencing techniques, in particular the transcriptomic analysis (RNA-seq) represents a validated technique to obtain a molecular characterization of human cancers. Moreover, it has been established that genetic susceptibility and environmental factors, such as microbial infections may contribute to carcinogenesis. We have characterized the different patterns of gene expression, using RNA-seq analysis and correlated these findings with gastric cancer histological subtypes.

cancer biology↗

bioRxiv2020

Hijacking SARS-Cov-2/ACE2 receptor interaction by natural and semi-synthetic steroidal agents acting on functional pockets on receptor binding region

The coronavirus disease 2019 (COVID-19) is a respiratory tract infection caused by the severe acute respiratory syndrome coronavirus (SARS)-CoV-2. In the light of the urgent need to identify novel approaches to be used in the emergency phase, a largely explored strategy has been the repurpose of clinically available drugs as new antivirals, by targeting different viral proteins. In this paper, we describe a drug repurposing strategy based on a virtual screening of druggable pockets located in the central β-sheet core of the SARS-CoV-2 Spike protein RBD supported by in vitro tests identifying several steroidal derivatives as SARS-CoV-2 entry inhibitors. Our results demonstrate that several potential binding sites exist in the SARS CoV-2 S protein, and that the occupancy of these pockets reduces the ability of the S protein RBD to bind to the ACE2 consensus in vitro. In particular, natural occurring and clinically available steroids as glycyrrhetinic and oleanolic acids, as well as the bile acids derivatives glyco-UDCA and obeticholic acid have been shown to be effective in preventing virus entry in the case of low viral load. All together, these results might help to define novel approaches to reduce the viral load by using SARS-CoV-2 entry inhibitors.Competing Interest StatementThis paper was supported by a research grant by BAR Pharmaceuticals S.r.L. to the Department of Pharmacy of the University of Napoli Federico II and to the Department of Surgical and Biomedical Sciences, University of Perugia. The authors declare the following competing financial interest(s): S.F., A.Z. and B.C. have filed an Italian patent application no.102020000011092 in the name of BAR Pharmaceuticals S.r.L. on the compounds described in this paper. View Full Text

pharmacology and toxicology↗