Μελέτη των πρωτεϊνών που ρυθμίζουν την ομοιόσταση του σιδήρου στο νευρικό σύστημα: ρόλος του σιδήρου σε νευροεκφυλιστικές διαταραχές

Abstract

Iron is one of the major elements for the preservation of life , but also capable for the destruction of it, since alterations in its balance does not cope with the proper function of the cell. Iron can be found in several states and in different protein complexes. This ability made him a vital elements of many biological complexes and pathways. The most common protein that stores iron is ferritin.Alterations in the homoistasis of iron and ferritin have dentrimental effects in the cell. One of the common tissues that is affected from the abnormalities in the iron metabolism is the neuronal tissue and especially the brain. The iron is located commonly in the basal gaglia of the brain and the quantitity is approximately the same with the amount of iron found in the liver. Iron is also present in the cells of the C.N.S. such us oligodendrocytes kai cells that produce myelin. The increase of iron in neurons, astrocytes and glia is being more obvious with increase of age. Specifically, regions such as hippocampus and substantia nigra accumulate iron normally but are susceptible in neuropathological changes that can be found in diseases, Alzheimers, Parkinson e.tc. In the present study we investigate the differential distribution of ferritin subunits in brain and we presented data showing that the redistribution of ferritin is age related. We show that in iron homoiostasis the secretoty pathway in conjuction with the proteasome pathway have vitla roles. We demonstrated that the the expression of ferritin subunits is essential for life since their disruption leads to leathality. Brian cells have different ways of handling iron and any intervention in their function can cause various defects such as neurodegeneration and movement disorders. Finally, we generated a model system for the study of iron metabolism and the relation with the neurodegeneration processes. The accumulation of hyperphosphorylated tau has been related to a group of dementing neurodegenerative diseases, known as Tauopathies. The six possible tau isoforms, products of alternative splicing of a unique transcript, are distributed mainly in the axons of central nervous system (CNS) neurons. Tau associates with microtubules and regulates their organization, stability and function including intraneuronal transport. With the exception of the familial disease Frontotemporal 372 dementia with parkinsonism linked to chromosome 17, which is associated with gene mutations, other tauopathies like Pick‘s and Alzheimer‘s disease, among others, are characterized by aggregates of hyperphosphorylated, at specific epitopes, normal tau isoforms. The hyperphosphorylated form of tau has reduced ability to bind to microtubules. As a result, it accumulates in the cytoplasm and aggregates into NFTs (neurofibrilar tanges), a characteristic pathological hallmark of many tauopathies. The heterogeneous clinical and cognitive profiles of tauopathies suggest differences in vulnerability of neuronal populations to tau levels, phosphorylation and mutations. .......................................................................