In vitro toxicity of nanoceria: effect of coating and stability in biofluids.

Due to the increasing use of nanometric cerium oxide in applications, concerns about the toxicity of these particles have been raised and have resulted in a large number of studies. We report here on the interactions between 7 nm anionically charged cerium oxide particles and living mammalian cells. By a modification of the particle coating including low-molecular weight ligands and polymers, two generic behaviours are compared: particles coated with citrate ions that precipitate in biofluids and particles coated with poly(acrylic acid) that are stable and remain nanometric.

Metastasis suppressor tetraspanin CD82/KAI1 regulates ubiquitylation of epidermal growth factor receptor.

Ligand-induced ubiquitylation of EGF receptor (EGFR) is an important regulatory mechanism that controls endocytic trafficking of the receptor and its signaling potential. Here we report that tetraspanin CD82/KAI1 specifically suppresses ubiquitylation of EGFR after stimulation with heparin-binding EGF or amphiregulin and alters the rate of recruitment of the activated receptor to EEA1-positive endosomes. The suppressive effect of CD82 is dependent on the heparin-binding domain of the ligand.

Segregative clustering of Lo and Ld membrane microdomains induced by local pH gradients in GM1-containing giant vesicles: a lipid model for cellular polarization.

Several cell polarization processes are coupled to local pH gradients at the membrane surface. We have investigated the involvement of a lipid-mediated effect in such coupling. The influence of lateral pH gradients along the membrane surface on lipid microdomain dynamics in giant unilamellar vesicles containing phosphatidylcholine, sphingomyelin, cholesterol, and the ganglioside GM1 was studied.

Making a tool of an artifact: the application of photoinduced Lo domains in giant unilamellar vesicles to the study of Lo/Ld phase spinodal decomposition and its modulation by the ganglioside GM1.

Electroformed giant unilamellar vesicles containing liquid-ordered Lo domains are important tools for the modeling of the physicochemical properties and biological functions of lipid rafts. Lo domains are usually imaged using fluorescence microscopy of differentially phase-partionioning membrane-embedded probes. Recently, it has been shown that these probes also have a photosensitizing effect that leads to lipid chemical modification during the fluorescence microscopy experiments.