Role of astrocytes in pathogenesis of multiple sclerosis and their participation in regulation of cerebral circulation.

There is about 30% higher risk of the myocardial infarction in patients diagnosed with multiple sclerosis (MS) than in people without MS. Increased risk of cardiovascular disease development positively correlates with levels of serum markers of an endothelial dysfunction, and may give rise to a global cerebral hypoperfusion. It appears that these complications precede progressive loss of axons, which mechanisms are complex and should be linked to a loss of ß2 adrenergic receptors on astrocytes of demyelinating lesions. Consequence of this deficiency, the cause of which is not known yet, is a decline in energy metabolism of axons. Moreover, the loss of these receptors is linked to a reduced redistribution of potassium ions by astrocytes, glutamate excitotoxicity and increase of calcium ion concentration in the axon with subsequent activation of necrotic processes. In addition to immunological aspects we should take into account also parameters of the functional state of endothelium when appropriate targeted therapy for patient is considered.

The delivery of ADP/ATP carrier protein to mitochondria probed by fusions with green fluorescent protein and beta-galactosidase.

The import of proteins into mitochondria is an essential process, largely investigated in vitro with isolated mitochondria and radioactively labeled precursors. In this study, we used intact cells and fusions with genes encoding two reporter proteins, green fluorescent protein (GFP) and beta-galactosidase (lacZ), to probe the import of the ADP/ATP carrier (AAC). Typical mitochondrial fluorescence was observed with AAC-GFP fusions containing at least one complete transmembrane loop. This confirms the results of in vitro analysis demonstrating that an internal targeting signal was present in each one of the three transmembrane loops of the carrier. The fusions of AAC fragments to beta-galactosidase demonstrated that the targeting signal was capable of delivering the reporter molecule to the mitochondrial surface, but not to internalize it to a protease-inaccessible location. The delivery to a protease-inaccessible location required the presence of more distal sequences present within the third (C-terminal) transmembrane loop of the carrier molecule. The results of our study provide an alternative for investigation in a natural context of mitochondrial protein import in cells when the isolation of intact, functional mitochondria is not achievable.