carbocyanines and laurdan

We compared the lateral structure of giant unilamellar vesicles (GUVs) composed of three pseudo binary mixtures of different glycosphingolipid (GSL), i.e. sulfatide, asialo-GM1 or GM1, with POPC. These sphingolipids possess similar hydrophobic residues but differ in the size and charge of their polar head group. Fluorescence microscopy experiments using LAURDAN and DiIC

Topics: 2-Naphthylamine; Carbocyanines; Fluorescent Dyes; G(M1) Ganglioside; Laurates; Lipid Bilayers; Microscopy, Fluorescence; Molecular Structure; Phosphatidylcholines; Sulfoglycosphingolipids; Unilamellar Liposomes

Receptor-ligand binding is an essential interaction for biological function. Oxidative stress can modify receptors and/or membrane lipid dynamics, thus altering cell physiological functions. The aim of this study is to analyze how oxidative stress may alter receptor-ligand binding and lipid domain distribution in the case of progesterone-induced blocking factor/progesterone-induced blocking factor-receptor. For membrane fluidity regionalization analysis of MEC-1 lymphocytes, two-photon microscopy was used in individual living cells. Lymphocytes were also double stained with AlexaFluor647/progesterone-induced blocking factor and Laurdan to evaluate -induced blocking factor/progesterone-induced blocking factor-receptor distribution in the different membrane domains, under oxidative stress. A new procedure has been developed which quantitatively analyzes the regionalization of a membrane receptor among the lipid domains of different fluidity in the plasma membrane. We have been able to establish a new tool which detects and evaluates lipid raft clustering from two-photon microscopy images of individual living cells. We show that binding of progesterone-induced blocking factor to progesterone-induced blocking factor-receptor causes a rigidification of plasma membrane which is related to an increase of lipid raft clustering. However, this clustering is inhibited under oxidative stress conditions. In conclusion, oxidative stress decreases membrane fluidity, impairs receptor-ligand binding and reduces lipid raft clustering.

Topics: 2-Naphthylamine; B-Lymphocytes; Carbocyanines; Cell Line, Tumor; Fluorescent Dyes; Humans; Hydrogen Peroxide; Laurates; Membrane Fluidity; Membrane Microdomains; Microscopy, Fluorescence, Multiphoton; Oxidative Stress; Pregnancy Proteins; Protein Binding; Receptors, Cytokine; Single-Cell Analysis; Staining and Labeling; Suppressor Factors, Immunologic