Neurodegeneration and nanomedicine General aim of the project
To evaluate the mechanisms involved in the pathogenesis of Alzheimer and prion-associated diseases. To devise nanotechnology strategies for the diagnosis and therapy of the diseases.
Background
Alzheimer
Plasma membrane has an important role in the oncoming and degenerative phase of Alzheimer disease (AD). Abeta is able to insert into the bilayer, interacting with lipids and changes in membrane cholesterol are able to affect Abeta formation. In the late years, an important contribution to the understanding of AD etiopathogenesis came from a consistent body of experimental results suggesting the involvement of lipids. APP is present in two cellular pools, one being indeed the lipid rafts compartment, where generation of Abeta is occurring; changes in membrane cholesterol concentration could shift APP between the compartments, modulating its processing by BACE.
Neurobiology
Abeta-lipid interaction and lipid rafts are important issues in the modulation of Abeta toxicity. The evaluation of this hypothesis will be the aim of the present project.
Nanotechnology
The postulated specificity of Abeta-lipid rafts interaction may have future therapeutic and diagnostic implications. In fact, recent studies opened the possibility to reduce the amount of peptide produced at the CNS by administration of gangliosides in the bloodstream.
Within the context of a project funded by E.U. (FP7), utilizing protocols set up in our laboratory for the production of lipid-based nanoparticles, we will evaluate the ability of these structures to bind Abeta peptide and stimulate its clearance from cells. The nanoparticles will be functionalized to cross the BBB.
Prion protein
It has been suggested that lipid composition may affect GPI-anchored proteins segregation in lipid rafts. A common sphingolipid-binding domain in Alzheimer, prion and HIV-1 proteins has been recently identified. For instance, the sortingof GPI-anchored proteins in polarized cell, related to their segregation within lipid rafts at the level of Golgi, is influenced by cell depletion of cholesterol or cell treatment with inhibitors of sphingolipid biosynthesis; addition of exogenous glycolipids brings on redistribution of the domains of these proteins within the plasma membrane. Some of these results have been achieved by using new techniques that we set up, able to detect domain formation in living cells.
The aim of the present investigation is to study the interaction between native prion protein and lipid domain, where it is naturally present and displays its physiological and pathogenetic activity. In particular this research will make use of liposomes constituted by naturally-occurring lipids in order to study: a) the existence of domains and the mechanisms underlying lipid domains formation; b) the conditions leading prion proteins extracted from natural sources to associate with lipid domains; c) the effect of the different lipid composition of GPI anchor and of polypeptidic and oligosaccharidic prion protein moieties changes on its in vitro reconstitution and on its association to domains.
Models to be used
Starting from the observation that the main problem in the study and diagnosis of AD lies in the impossibility to utilize CNS specimen to investigate dynamic events, our investigation will make use of either animal (cultured rat hippocampal cells) or human models (cultured skin fibroblasts from AD and MCI patients, provided by the clinical U.O., and cultured neuroblastoma cells). The use of peripheral models for the study of the biochemical mechanisms underlying neurodegenerative diseases has already been validated by several investigations.
A promising approach consists in the use of nanoparticles such as liposomes, SLN, PNP. They are a widely used nano-scaled systems particularly suitable to carry out therapy and diagnosis in vivo. In fact, these nanoparticles are biocompatible, non toxic, long circulating and can be functionalized with different ligands (for Abeta/prion ; imaging contrast agents, ligands to cross the BBB)
References
Wakabayashi M (2005) Biochem Biophys Res Commun. 328, 1019.
Pitto M. Raimondo F. , Zoia C. , Ferrarese C., Masserini M. (2005) Neurobiol Aging, 26, 833.
W. Gibson Wood et al. (2002) Neurobiol. Aging, 23, 685.
Kai Simons et al. (2002) Journal of Clinical Investigation 110, 597.
Snowdon DA et al., (2000) Am J Clin. Nutr., 71, 993.
Matsuoka Y et al., (2003) J. Neurosci. 23, 29.
Kruman I. et al., (2002), J Neurosci., 22, 1752.
Mahfoud, R., Garmy, N., Maresca, M., Yahi, N., Puigserver, A., and Fantini,J. (2002) J Biol Chem. 277:11292-6.
Simons, M., Friedrichson, T., Schulz, J. B., Pitto, M., Masserini, M., and Kurzchalia T. V. (1999) Mol. Biol. Cell 10, 3187-3196.
Pitto, M., Palestini, P. Ferraretto, A. Masserini, M. Flati, S. Pavan, A. and Bottiroli G.(1999) Biochem. J. 344, 177-184.
Palestini, P., Pitto, M., Tettamanti, G., Masserini, M. (1998) Biochemistry 37, 3143-3148
|
