Phosphorylation-induced conformation of beta(2)-adrenoceptor related to arrestin recruitment revealed by NMR

The C-terminal region of G-protein-coupled receptors (GPCRs), stimulated by agonist binding, is phosphorylated by GPCR kinases, and the phosphorylated GPCRs bind to arrestin, leading to the cellular responses. To understand the mechanism underlying the formation of the phosphorylated GPCR-arrestin complex, we performed NMR analyses of the phosphorylated beta(2)-adrenoceptor (beta(2)AR) and the phosphorylated beta(2)AR-beta-arrestin 1 complex, in the lipid bilayers of nanodisc. Here we show that the phosphorylated C-terminal region adheres to either the intracellular side of the transmembrane region or lipids, and that the phosphorylation of the C-terminal region allosterically alters the conformation around M215(5.54) and M279(6.41), located on transemembrane helices 5 and 6, respectively. In addition, we found that the conformation induced by the phosphorylation is similar to that corresponding to the beta-arrestin-bound state. The phosphorylation-induced structures revealed in this study propose a conserved structural motif of GPCRs that enables beta-arrestin to recognize dozens of GPCRs.Peer reviewe

Management of Diabetes Associated with Nephrotic Syndrome: Therapeutic Potential of Dapagliflozin for Protracted Volume Retention

A 48-year-old female was admitted to our hospital presenting with a chief complaint of progressive swelling because of diabetic nephrotic syndrome. Dapagliflozin seemed to play a role in accelerating the patient's urinary sodium excretion as well as reducing gross fluid retention despite the fact that her nephrotic condition was resistant to furosemide. Our experience emphasizes a potential novel approach to overcoming loop diuretic resistance using this agent among some subsets of type 2 diabetic subjects complicated with severe volume accumulation. We believe that combination treatment consisting of dapagliflozin and furosemide may produce diuretic synergy via sequential nephron blockade. The accumulation of more experience with additional cases similar to ours requires continuous and careful attention

Effluent Tenascin-C Levels Reflect Peritoneal Deterioration in Peritoneal Dialysis: MAJOR IN PD Study

Peritoneal deterioration causing structural changes and functional decline is a major complication of peritoneal dialysis (PD). The aim of this study was to explore effluent biomarkers reflecting peritoneal deterioration. In an animal study, rats were intraperitoneally administered with PD fluids adding 20 mM methylglyoxal (MGO) or 20 mM formaldehyde (FA) every day for 21 days. In the MGO-treated rats, tenascin-C (TN-C) levels in the peritoneal effluents were remarkably high and a cluster of TN-C-positive mesothelial cells with epithelial-to-mesenchymal transition- (EMT-) like change excessively proliferated at the peritoneal surface, but not in the FA-treated rats. Effluent matrix metalloproteinase-2 (MMP-2) levels increased in both the MGO- and FA-treated rats. In a clinical study at 18 centers between 2006 and 2013, effluent TN-C and MMP-2 levels were quantified in 182 PD patients with end-stage renal disease. Peritoneal function was estimated using the peritoneal equilibration test (PET). From the PET results, the D/P Cr ratio was correlated with effluent levels of TN-C (ρ = 0.57, p<0.001) and MMP-2 (ρ = 0.73, p<0.001). We suggest that TN-C in the effluents may be a diagnostic marker for peritoneal deterioration with EMT-like change in mesothelial cells in PD

Therapeutic Challenges to End-Stage Kidney Disease in a Patient with Tetralogy of Fallot

In this report, we describe the case of an end-stage kidney disease patient with tetralogy of Fallot (TOF). A 33-year-old female with TOF was admitted to our hospital with complaints of general fatigue and appetite loss probably due to uremic milieu. She was ultimately treated with peritoneal dialysis (PD) with a favorable clinical course. TOF patients with chronic kidney disease are not exceptional, although the currently available information regarding the association between TOF and renal failure severe enough to require dialysis treatment is limited. We also discuss the complex processes of how and why PD was selected as a mode of chronic renal replacement therapy in this case

Performing Anticoagulation: A Puzzling Case of Cholesterol Embolization Syndrome

The avoidance of any form of anticoagulation is advised in cases of cholesterol embolization syndrome (CES). We herein describe a case of CES in a man with a history of unprovoked pulmonary embolism for which warfarinization was performed. Despite anecdotal reports of successful anticoagulation in CES patients with certain indications, irreversible renal failure, which was sufficiently severe to require chronic hemodialysis, eventually developed in our patient. Our results emphasize the pitfalls of this procedure, which imply its limited feasibility and safety. Several therapeutic concerns associated with this case are also discussed