GPR17: Molecular modeling and dynamics studies of the 3-D structure and purinergic ligand binding features in comparison with P2Y receptors

<p>Abstract</p> <p>Background</p> <p>GPR17 is a G-protein-coupled receptor located at intermediate phylogenetic position between two distinct receptor families: the P2Y and CysLT receptors for extracellular nucleotides and cysteinyl-LTs, respectively. We previously showed that GPR17 can indeed respond to both classes of endogenous ligands and to synthetic compounds active at the above receptor families, thus representing the first fully characterized non-peptide "hybrid" GPCR. In a rat brain focal ischemia model, the selective <it>in vivo </it>knock down of GPR17 by anti-sense technology or P2Y/CysLT antagonists reduced progression of ischemic damage, thus highlighting GPR17 as a novel therapeutic target for stroke. Elucidation of the structure of GPR17 and of ligand binding mechanisms are the necessary steps to obtain selective and potent drugs for this new potential target. On this basis, a 3-D molecular model of GPR17 embedded in a solvated phospholipid bilayer and refined by molecular dynamics simulations has been the first aim of this study. To explore the binding mode of the "purinergic" component of the receptor, the endogenous agonist UDP and two P2Y receptor antagonists demonstrated to be active on GPR17 (MRS2179 and cangrelor) were then modeled on the receptor.</p> <p>Results</p> <p>Molecular dynamics simulations suggest that GPR17 nucleotide binding pocket is similar to that described for the other P2Y receptors, although only one of the three basic residues that have been typically involved in ligand recognition is conserved (Arg255). The binding pocket is enclosed between the helical bundle and covered at the top by EL2. Driving interactions are H-bonds and salt bridges between the 6.55 and 6.52 residues and the phosphate moieties of the ligands. An "accessory" binding site in a region formed by the EL2, EL3 and the Nt was also found.</p> <p>Conclusion</p> <p>Nucleotide binding to GPR17 occurs on the same receptor regions identified for already known P2Y receptors. Agonist/antagonist binding mode are similar, but not identical. An accessory external binding site could guide small ligands to the deeper principal binding site in a multi-step mechanism of activation. The nucleotide binding pocket appears to be unable to allocate the leukotrienic type ligands in the same effective way.</p

Extracellular vesicles in the urine: markers and mediators of tissue damage and regeneration

As in several body fluids, urine is a rich reservoir of extracellular vesicles (EVs) directly originating from cells facing the urinary lumen, including differentiated tubular cells, progenitor cells and infiltrating inflammatory cells. Several markers of glomerular and tubular damage, such as WT-1, ATF3 and NGAL, as well as of renal regeneration, such as CD133, have been identified representing an incredible source of information for diagnostic purposes. In addition, urinary extracellular vesicles (uEVs) appear to be involved in the cell-to-cell communication along the nephron, although this aspect needs further elucidation. Finally, uEVs emerge as potential amplifying or limiting factors in renal damage. Vesicles from injured cells may favour fibrosis and disease progression whereas those from cells with regenerative potential appear to promote cell survival. Here, we will discuss the most recent findings of the literature, on the light of the role of EVs in diagnosis and therapy for damage and repair of the renal tissue

Reproductive trend of White Stork, Ciconia ciconia, in the area of Vercelli and Biella

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Pulmonary toxicity in a renal transplant recipient treated with amiodarone and everolimus: a case of hypothetical synergy and a proposal for a screening protocol

Pneumotoxic drugs like amiodarone and m-TOR inhibitors (m-TORi) may be administered contemporaneously in therapy for patients who had renal transplants. We present a case of amiodarone pulmonary toxicity (APT) in a patient treated with amiodarone and everolimus. A 57-year-old Caucasian male, under treatment with both everolimus (for 3 years) and amiodarone (for 2 months), presented with fever, dyspnoea and a negative chest X-ray after his second kidney transplant with suboptimal serum creatinine (3 mg/dl). A non-contrastive high-resolution CT scan showed bilateral interstitial lung disease with an associated reduction in carbon monoxide diffusing capacity. Bronchoalveolar lavage (BAL) was negative for an infection, but BAL cytology was suitable for APT (50% of ‘foamy’ macrophages). A complete recovery was achieved after amiodarone interruption and an oral steroid therapy increase. Everolimus was continued. His kidney function remained unchanged in the upcoming months. In conclusion, we suggest a possible synergistic effect between m-TORi and amiodarone. Furthermore, we propose a diagnostic algorithm that can be used as a surveillance tool to identify a potential initial lung damage in patients treated with 1 or more pneumotoxic drugs