New Fluorescence Microscopy Approaches to Explore the Influence of Sphingolipids on Lateral Organization of Biomembranes: From Artificial Systems to Cellular Membranes

MARTÍN MIGUEL DODES TRAIAN; SUSANA SANCHEZ; VALERIA LEVI

Sphingomyelin and Ceramides - Ocurrence, Biosynthesis and Role in Disease

Nova Science Publishers

Lugar: New York; Año: 2015; p. 1 - 19

Sphingolipids are involved in a wide range of physiological and pathological processes none only as signaling molecules but also as key structural components regulating the lateral organization of cellular membranes. The preferential interaction of these biomolecules with cholesterol support the actual theory related with membrane heterogeneity in vivo, the raft theory. Rafts are believed to be highly-dynamic and small domains enriched in sphingolipids, cholesterol and certain membrane proteins present in the membrane of cells. The idea of these domains compartmentalizing cellular processes is a central hypothesis in biomedical research from immunology, virology, neurobiology to cancer.The use of microscopy to study lateral heterogeneity in biological membranes was developed during the nineties with the use of artificial models systems such as giant unillamelar vesicles and supported-lipid. The combination of confocal and two-photon microscopy techniques with fluorescent and solvatochromic probes like Laurdan enabled the acquisition of spatially-resolved information about the fluidity and/or order of artificial bilayers showing phase segregation. For the detection of domain separation in vivo the development of new techniques combining Laurdan imaging with fluorescence fluctuation spectroscopy was developed and allowed the detection of highly-packed microdomains in natural cell membranes. In this article we review these exciting new approaches that open a window to further characterize these sphingolipid-enriched domains in cell membranes during both physiological and pathological processes.