Microfluorimetric and biochemical study of the membrane organization of oligodendrocytes when subjected to cholesterol modulation factors (R-2103)

Transforming growth factor- (TGF-) is a regulatory cytokine that mediates physiological processes and exhibits an anti-inflammatory activity. Understanding the function and regulation of TGF- offers therapeutic promise for the control of autoimmune diseases such as multiple sclerosis. Some studies relate the TGF- receptor function to some lipo-proteic supramolecular structures in membranes, so called rafts. Rafts have been defined as small (10200 nm), heterogeneous, highly dynamic, sterol- and sphingolipid-enriched domains that compartmentalize cellular processes. There is substantial evidence in the literature concerning the presence of rafts in oligodendrocytes (OLGs), the myelin forming cells in the central nervous system. However, the current knowledge about the existence and function of lipid rafts in OLGs is mainly based on results obtained by detergent extraction and co-localization imaging. The invasive character of detergent methods and the restricted resolution of the pixel based co-localization approaches raise some questions about the interpretation of the obtained results. The synthesis of cholesterol, a major raft component, can be blocked by statins. Statins are drugs to treat hypercholesterolaemia. Their use has been suggested in treating Multiple Sclerosis patients but the mechanism of the neuroprotective effects of statins is only partly understood. Cholesterol in the membrane can also be influenced by endogenous processes. Liver X receptors (LXRs) are sterol-dependent nuclear receptors activated in response to cellular cholesterol excess. LXR target genes promote the efflux of cellular cholesterol and help maintain sterol homeostasis. They can be activated also by the synthetic agonist T0-901317 (T09). This project aims to develop new microfluorimetric methods in the investigation of the membrane organization (rafts) in living cells. This new methods will be used to study changes in membrane organization of oligodendrocytes when subjected to simvastatin or T09. The effect of cholesterol modulation on the TGF- action mechanism involving raft/non-raft partitioning of the TGF- receptor and on TGF- induced apoptosis will be investigated.

Keywords:cell membrane organization, cholesterol, microfluorimetric methods, multiple sclerosis, total internal reflection fluorescence microscopy (TIRF)

Disciplines:Biological sciences, Electrical and electronic engineering, (Bio)medical engineering, Computer engineering, information technology and mathematical engineering, Basic sciences, Clinical sciences, Translational sciences