Elucidation of Distinct Modular Assemblies of Smoothened Receptor by Bitopic Ligand Measurement.

Class F G protein-coupled receptors are characterized by a large extracellular domain (ECD) in addition to the common transmembrane domain (TMD) with seven α-helixes. For smoothened receptor (SMO), structural studies revealed dissected ECD and TMD, and their integrated assemblies. However, distinct assemblies were reported under different circumstances. Using an unbiased approach based on four series of cross-conjugated bitopic ligands, we explore the relationship between the active status and receptor assembly. Different activity dependency on the linker length for these bitopic ligands corroborates the various occurrences of SMO assembly. These results reveal a rigid "near" assembly for active SMO, which is in contrast to previous results. Conversely, inactive SMO adopts a free ECD, which would be remotely captured at "far" assembly by cholesterol. Altogether, we propose a mechanism of cholesterol flow-caused SMO activation involving an erection of ECD from far to near assembly.

Arginyl-fructosyl-glucose, a Major Maillard Reaction Product of Red Ginseng, Attenuates Cisplatin-Induced Acute Kidney Injury by Regulating Nuclear Factor κB and Phosphatidylinositol 3-Kinase/Protein Kinase B Signaling Pathways.

Recently, although ginseng ( Panax ginseng C. A. Meyer) and its main component saponins (ginsenosides) have been reported to exert protective effects on cisplatin (CDDP)-induced acute kidney injury (AKI), the beneficial activities of non-saponin on CDDP-induced AKI is little known. This research was designed to explore the protective effect and underlying mechanism of arginyl-fructosyl-glucose (AFG), a major and representative non-saponin component generated during the process of red ginseng, on CDDP-caused AKI. AFG at doses of 40 and 80 mg/kg remarkably reversed CDDP-induced renal dysfunction, accompanied by the decreased levels of serum creatinine and blood urea nitrogen. Interestingly, all of oxidative stress indices were ameliorated after pretreatment with AFG continuously for 10 days. Importantly, AFG relieved CDDP-induced inflammation and apoptosis in part by mitigating the cascade initiation steps of nuclear factor κB signals and regulating the participation of the phosphatidylinositol 3-kinase/protein kinase B signal pathway. In conclusion, these results clearly provide strong rationale for the development of AFG to prevent CDDP-induced AKI.

Platycodon grandiflorum Saponins Ameliorate Cisplatin-Induced Acute Nephrotoxicity through the NF-κB-Mediated Inflammation and PI3K/Akt/Apoptosis Signaling Pathways.

Although cisplatin is a potent chemotherapeutic agent against cancers, its clinical application is seriously limited by its severe side effects of nephrotoxicity. Previous studies reported that saponins isolated from the roots of Platycodon grandiflorum (PGS) exerted protective effects in various animal models of renal injury, with no confirmation on cisplatin-induced injury. This study was designed to investigate the protective effect of PGS (15 and 30 mg/kg) on cisplatin-induced kidney injury in mice. The levels of serum creatinine (CRE) and blood urea nitrogen (BUN), and renal histopathology demonstrated the protective effect of PGS against cisplatin-induced kidney injury. PGS exerted anti-inflammation effects via suppressing nuclear factor-kappa B (NF-κB) activation and alleviating the cisplatin-induced increase in inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) in kidney tissues. The expressions of phosphorylation of phosphatidylinositol 3-kinase/protein kinase B and its downstream apoptotic factors, such as Bcl-2 and caspase families were regulated by PGS in a dose-dependent manner. In conclusion, PGS exerted kidney protection effects against cisplatin-induced kidney injury by inhibiting the activation of NF-κB and regulating PI3K/Akt/apoptosis signaling pathways in mice.

Unconjugated bilirubin ameliorates the inflammation and digestive protease increase in TNBS-induced colitis.

The authors previously demonstrated that unconjugated bilirubin (UCB) may inhibit the activities of various digestive proteases, including trypsin and chymotrypsin. The digestive proteases in the lower gut are important in the pathogenesis of inflammatory bowel diseases. The effects of UCB on the inflammation and levels of digestive proteases in feces of rats with colitis have not yet been revealed. The present study investigated the effect of UCB on the inflammatory status and levels of trypsin and chymotrypsin in the feces of rats with trinitrobenzenesulfonic acid (TNBS)­induced colitis. The data indicated that treatment with TNBS resulted in a marked reduction in weight gain, which was significantly alleviated in UCB­treated rats. Furthermore, UCB treatment alleviated the inflammation induced by TNBS, detected via macroscopic damage and microscopic inflammation scores, and pro­inflammatory markers including myeloperoxidase (MPO), tumor necrosis factor (TNF)­α and interleukin (IL)­1ß. Furthermore, rats with colitis demonstrated significant increases in fecal trypsin and chymotrypsin levels, whereas UCB treatment significantly alleviated these increases. A significant positive correlation was additionally revealed among the pro­inflammatory markers (MPO, TNF­α and IL­1ß) and fecal digestive proteases (trypsin and chymotrypsin) in colitis. The results of the present study demonstrated that UCB ameliorated the inflammation and digestive protease increase in TNBS-induced colitis.

Sucralose Increases Antimicrobial Resistance and Stimulates Recovery of Escherichia coli Mutants.

Because of heavy use of antimicrobials, antimicrobial resistance in bacteria has become of great concern. The effect of some widely used food additives such as sucralose on bacteria in the gut and the environment has also drawn increasing attention. In this study, we investigated the interaction between antimicrobials and sucralose impacting antimicrobial resistance and mutation of Escherichia coli (E. coli). To examine antimicrobial resistance and mutation frequency, different subinhibitory concentrations of sucralose were added to cultures of E.coli BW25113 that were then treated with antimicrobials, oxolinic acid, or moxifloxacin. Then the E.coli were assayed for bacterial survival and recovery of mutants resistant to an unrelated antimicrobial, rifampicin. Pre-treatment of E.coli BW25113 with 1/2 minimal inhibitory concentration (MIC) of sucralose increased the survival rate in oxolinic acid or moxifloxacin. A 1/3 MIC of sucralose increased rifampicin-resistant mutation rate of E.coli BW25113 after 72 h, while rifampicin-resistant mutation rate was increased when co-treated with 1/8 MIC, 1/4 MIC, 1/3 MIC sucralose, and oxolinic acid after 24 h. Sucralose can increase the antimicrobial resistance and mutation frequency of E.coli to some antimicrobials.

[Study of the effect and mechanism of spastic paraplegia 21 protein on the replication of hepatitis B virus].

OBJECTIVE: To study the effect of human spastic paraplegia 21 protein (SPG21) on the replication of hepatitis B virus(HBV) and its regulatory mechanism. METHODS: HBV infectious clone pHBV1.3 and its promoter pHBV-Luc were transfected respectively into HepG2 cells with SPG21 of different concentrations, HBsAg and HBeAg in the supernatants were measured by enzyme linked immunosorbent assay (ELISA), expression of HBV core mRNA and protein were detected by RT-PCR and western blot, covalently closed circular DNA(ccc DNA) levels were measured by real-time PCR, and HBV promoter activity was measured by luminometer fluorescence detector. RESULTS: Expression of HBsAg, HBeAg, HBV core protein and cccDNA were upregulated by SPG21 as well as HBV promoter activity in a dose-dependent approach. The activity of HBV promoter increased to 1.63, 3.09 and 4.66 times in HepG2 cells treated with 50mug/ml, 100mug/ml and 200mug/ml SPG21 respectively during 48 hour-treated ( P less than 0.05), as compared to the control group. CONCLUSIONS: SPG21 can enhance the replication of HBV in HepG2 cells.