Duffy antigen receptor for chemokines mediates chemokine endocytosis through a macropinocytosis-like process in endothelial cells

Background: The Duffy antigen receptor for chemokines (DARC) shows high affinity binding to multiple inflammatory CC and CXC chemokines and is expressed by erythrocytes and endothelial cells. Recent evidence suggests that endothelial DARC facilitates chemokine transcytosis to promote neutrophil recruitment. However, the mechanism of chemokine endocytosis by DARC remains unclear. Methodology/Principal Findings: We investigated the role of several endocytic pathways in DARC-mediated ligand internalization. Here we report that, although DARC co-localizes with caveolin-1 in endothelial cells, caveolin-1 is dispensable for DARC-mediated 125I-CXCL1 endocytosis as knockdown of caveolin-1 failed to inhibit ligand internalization. 125I-CXCL1 endocytosis by DARC was also independent of clathrin and flotillin-1 but required cholesterol and was, in part, inhibited by silencing Dynamin II expression. 125I-CXCL1 endocytosis was inhibited by amiloride, cytochalasin D, and the PKC inhibitor Gö6976 whereas Platelet Derived Growth Factor (PDGF) enhanced ligand internalization through DARC. The majority of DARC-ligand interactions occurred on the endothelial surface, with DARC identified along plasma membrane extensions with the appearance of ruffles, supporting the concept that DARC provides a high affinity scaffolding function for surface retention of chemokines on endothelial cells. Conclusions/Significance: These results show DARC-mediated chemokine endocytosis occurs through a macropinocytosis-like process in endothelial cells and caveolin-1 is dispensable for CXCL1 internalization. © 2011 Zhao et al

ERECTILE DYSFUNCTION TREATMENT USING SUBCUTANEOUS IMPLANTS WITH A LONG-TERM EFFECT

Introduction. The article describes a new method of improving erectile function by incerting long-acting subcutaneous implants with the phosphodiesterase 5 (PDE 5) inhibitor. The aim of the study: To evaluate the effectiveness of tadalafil in the treatment of erectile dysfunction using bioidentical pellets. Materials and methods: The study included 10 men under 65 years of age who had suffered from erectile dysfunction for more than 1 year. For the examination before and 4 months after the intervention, the following were performed: filling out the MIEF-5 questionnaire, phical examination, Doppler of penile vessels, «Erection Hardness Scale», laboratory examination (general and biochemical blood tests, general urine analysis and hormonal testing, including determination of the levels of total testosterone, free testosterone, prolactin, estradiol and dehydroepiandrosterone sulfate. All patients received implants with bioidentical tadalafil 75 mg. The pellet was inserted in a sterile operating room through a 3 mm skin incision in the outer quadrant of the gluteal region and inserting the substance into the subcutaneous fat. Results: All patients showed an improvement in MIEF-5 from 14.7 ± 2.75 to 20.7 ± 1.49, an increase in systolic blood flow velocity and penile rigidity at the tenth minute after prostaglandin E1 injection on Doppler vascular examination. Conclusion: This study demonstrated the efficacy of tadalafil by pellet administration in the treatment of erectile dysfunction in men younger than 65 years

Clustering and Lateral Concentration of Raft Lipids by the MAL Protein

MAL, a compact hydrophobic, four-transmembrane-domain apical protein that copurifies with detergent-resistant membranes is obligatory for the machinery that sorts glycophosphatidylinositol (GPI)-anchored proteins and others to the apical membrane in epithelia. The mechanism of MAL function in lipid-raft–mediated apical sorting is unknown. We report that MAL clusters formed by two independent procedures—spontaneous clustering of MAL tagged with the tandem dimer DiHcRED (DiHcRED-MAL) in the plasma membrane of COS7 cells and antibody-mediated cross-linking of FLAG-tagged MAL—laterally concentrate markers of sphingolipid rafts and exclude a fluorescent analogue of phosphatidylethanolamine. Site-directed mutagenesis and bimolecular fluorescence complementation analysis demonstrate that MAL forms oligomers via ϕxxϕ intramembrane protein–protein binding motifs. Furthermore, results from membrane modulation by using exogenously added cholesterol or ceramides support the hypothesis that MAL-mediated association with raft lipids is driven at least in part by positive hydrophobic mismatch between the lengths of the transmembrane helices of MAL and membrane lipids. These data place MAL as a key component in the organization of membrane domains that could potentially serve as membrane sorting platforms