👤 Paola Orlandi

Understudied orphan GPCRs lack identified natural ligands, yet understanding their function is critical for therapeutic development. GPRC5B is a brain-enriched, retinoic acid (RA)-induced orphan GPCR. While RA is used to treat severe acne, chronic exposure is associated with depression, likely due to its inhibition of adult hippocampal neurogenesis. Here, we tested whether GPRC5B plays a role in the molecular and cellular mechanisms underlying RA-induced depressive-like behaviors in mice by suppressing adult hippocampal neurogenesis. We found that Gprc5b knockout (KO) mice were resilient to RA-induced behavioral effects and that RA increased GPRC5B expression in the hippocampal neurogenic subgranular zone. This correlated with RA-mediated inhibition of adult hippocampal neurogenesis, an effect absent in Gprc5b KO mice, which also exhibited a larger pool of proliferative neuronal stem cells. Collectively, these findings suggest that GPRC5B mediates RA-induced anti-neurogenic effects and depressive-like behaviors. Show less

Macrophages express numerous G protein-coupled receptors (GPCRs) that regulate adhesion, migration, and activation, but the function of orphan receptor GPRC5B in macrophages is unknown. Both resident peritoneal and bone marrow-derived macrophages from myeloid-specific GPRC5B-deficient mice show increased migration and phagocytosis, resulting in improved bacterial clearance in a peritonitis model. In other models such as myocardial infarction, increased myeloid cell recruitment has adverse effects. Mechanistically, we found that GPRC5B physically interacts with GPCRs of the prostanoid receptor family, resulting in enhanced signaling through the prostaglandin E receptor 2 (EP2). In GPRC5B-deficient macrophages, EP2-mediated anti-inflammatory effects are diminished, resulting in hyperactivity. Using in silico modelling and docking, we identify residues potentially mediating GPRC5B/EP2 dimerization and show that their mutation results in loss of GPRC5B-mediated facilitation of EP2 signaling. Finally, we demonstrate that decoy peptides mimicking the interacting sequence are able to reduce GPRC5B-mediated facilitation of EP2-induced cAMP signaling in macrophages. Show less

The aim of our study is to investigate in vitro and in vivo MC4R as a novel target in melanoma using the selective antagonist ML00253764 (ML) alone and in combination with vemurafenib, a B-rafV600E inhibitor. The human melanoma B-raf mutated A-2058 and WM 266-4 cell lines were used. An MC4R null A-2058 cell line was generated using a CRISPR/Cas9 system. MC4R protein expression was analysed by western blotting, immunohistochemistry, and immunofluorescence. Proliferation and apoptotic assays were performed with ML00253764, whereas the synergism with vemurafenib was evaluated by the combination index (CI) and Loewe methods. ERK1/2 phosphorylation and BCL-XL expression were quantified by western blot. In vivo experiments were performed in Athymic Nude-Foxn1 Show less

Pancreatic cancer is a highly lethal disease, often diagnosed at advanced stages, with a 5-year overall survival rate of around 10%. Current treatments have limited effectiveness, underscoring the need for new therapeutic options. This scoping review aims to identify and summarize preclinical and clinical studies on FGFR (Fibroblast Growth Factor Receptor) inhibitors, including tyrosine kinase inhibitors (TKIs) and FGFR-specific inhibitors, in pancreatic cancer with FGFR alterations. We included studies analyzing efficacy, safety, and survival outcomes in various populations. A comprehensive search across major databases identified 73 relevant studies: 32 preclinical, 16 clinical, and 25 from gray literature. The clinical trials focused primarily on efficacy (20 studies) and safety (14 studies), with fewer studies addressing survival outcomes. FGFR1 was the most studied alteration, followed by FGFR2 and FGFR4. Although FGFR alterations are relatively rare in pancreatic cancer, the available data, including promising real-life outcomes, suggest significant potential for FGFR inhibitors. However, more extensive research is needed to identify the correct genetic drivers and gather robust survival data. Ongoing and future trials are expected to provide more comprehensive insights, potentially leading to improved targeted therapies for pancreatic cancer patients with FGFR alterations. Show less

Orphan G Protein Coupled Receptors (GPCRs) are GPCRs whose endogenous ligands are unknown or still debated. Due to the lack of pharmacological modulators, the physiological function of orphan GPCRs is understudied. However, relevant physiological roles associated with orphan GPCRs have been revealed by analysis of animal models and genome wide association studies illuminating an untapped potential for drug discovery. G Protein Coupled Receptor class C Group 5 Member B (GPRC5B) is among the most expressed GPCRs in the central nervous system. Thus, the expression profiling of GPRC5B is an essential step toward understanding GPRC5B function in health and disease. In this study, we generated new GPRC5B polyclonal antibodies and investigated the expression levels of GPRC5B across different organs and brain regions. We identified high levels of GPRC5B glycosylation both in transfected cells and in mouse brain. Moreover, Show less

G protein coupled receptors (GPCRs) are the main mediators of signal transduction in the central nervous system. Therefore, it is not surprising that many GPCRs have long been investigated for their role in the development of anxiety and mood disorders, as well as in the mechanism of action of antidepressant therapies. Importantly, the endogenous ligands for a large group of GPCRs have not yet been identified and are therefore known as orphan GPCRs (oGPCRs). Nonetheless, growing evidence from animal studies, together with genome wide association studies (GWAS) and post-mortem transcriptomic analysis in patients, pointed at many oGPCRs as potential pharmacological targets. Among these discoveries, we summarize in this review how emotional behaviors are modulated by the following oGPCRs: ADGRB2 (BAI2), ADGRG1 (GPR56), GPR3, GPR26, GPR37, GPR50, GPR52, GPR61, GPR62, GPR88, GPR135, GPR158, and GPRC5B. Show less

HER2-overexpression promotes malignancy by modulating signalling molecules, which include PTPs/DSPs (protein tyrosine and dual-specificity phosphatases). Our aim was to identify PTPs/DSPs displaying HER2-associated expression alterations. HER2 activity was modulated in MDA-MB-453 cells and PTPs/DSPs expression was analysed with a DNA oligoarray, by RT-PCR and immunoblotting. Two public breast tumor datasets were analysed to identify PTPs/DSPs differentially expressed in HER2-positive tumors. In cells (1) HER2-inhibition up-regulated 4 PTPs (PTPRA, PTPRK, PTPN11, PTPN18) and 11 DSPs (7 MKPs [MAP Kinase Phosphatases], 2 PTP4, 2 MTMRs [Myotubularin related phosphatases]) and down-regulated 7 DSPs (2 MKPs, 2 MTMRs, CDKN3, PTEN, CDC25C); (2) HER2-activation with EGF affected 10 DSPs (5 MKPs, 2 MTMRs, PTP4A1, CDKN3, CDC25B) and PTPN13; 8 DSPs were found in both groups. Furthermore, 7 PTPs/DSPs displayed also altered protein level. Analysis of 2 breast cancer datasets identified 6 differentially expressed DSPs: DUSP6, strongly up-regulated in both datasets; DUSP10 and CDC25B, up-regulated; PTP4A2, CDC14A and MTMR11 down-regulated in one dataset. Several DSPs, mainly MKPs and, unexpectedly, MTMRs, were altered following HER2-modulation in cells and 3 DSPs (DUSP6, CDC25B and MTMR11) were altered in both cells and tumors. Among these, DUSP6, strongly up-regulated in HER2-positive tumors, would deserve further investigation as tumor marker or potential therapy target. Show less