╨╧рб▒с>■  >@■   =                                                                                                                                                                                                                                                                                                                                                                                                                                                ье┴'` Ё┐·6bjbjы╚ы╚ ?8ЙвЙв7      дддддддд╕АААА М ╕b ╢ддддддддБ Г Г Г Г Г Г $ hАкз uд[ дд[ [ з дддд E E E [ жддддБ E [ Б E E ддE дШ └Ь/&▄6╩А :E Б 2 0b E *; *E *дE <д>т,E $2)дддз з ; дддb [ [ [ [ ╕╕╕$▄д╕╕╕▄╕╕╕дддддд     Daniel Witter - Biomedical Student Joint winner of the 2007 Peter Carlton Jones Award Daniel, is a third year D Phil student working at the laboratory of Dr Fran Platt at the Department of Pharmacology, University of Oxford. He was joint winner of the Peter Carlton Jones Memorial Award this year for his work on comparison of NPC neuropathology with that found in AlzheimerТs disease. Lay Summary Endosomes, which are small membrane bound compartments, operate within cells as transporters of molecules from outside of the cell to points of recycling and utilisation. The NPC1 defect interferes with this transport mechanism and this results in many cellular defects such as storage, mistrafficking and other problems. It is suspected that these defects ultimately lead to cell death, especially in neurons. Some of the cellular defects are also found in Alzheimer s disease e.g. endosome trafficking, involvement of cholesterol, elevation of proteins of the amyloid beta (A▓) family and tangles of proteins within the cell. The A▓ protein is usually harmless but can fold into a form that makes it toxic to the cell. This generally happens when it binds to another type of molecule. A modified form of cholesterol, atheronal-B was suspected as affecting the toxicity of small A▓ formations and this has been the subject of this study. Atheronal-B is itself toxic to cells at low concentrations and linkage to small A▓ groups could cause an increase in toxicity. The question was, are these molecules found together in NPC cells? Results from NPC muse brain cells show the elevated presence of these two proteins and their collocation. Using membrane models of endosomes, it has been possible to show that inclusion of atheronal-B can accelerate the aggregation of A▓ to its cytotoxic state. Aspects of Neurodegeneration in NPC disease Niemann-Pick type C disease (NPC) is a neurodegenerative sphingolipid storage disease. It primarily affects children, most of whom do not live past their teens. It is the result of a mutation that causes the loss of function of the NPC1 protein. The actual role of this protein remains unknown, but it is thought to influence sterol trafficking, as it shares sequence homology with a variety of other sterol-sensing or sterol-binding proteins. The loss of function of this protein results in the pathological features associated with NPC disease, including cholesterol and sphingolipid storage and mistrafficking, as well as widespread inflammation in both the central nervous system and the periphery. The disease is especially devastating because of the severe neurodegeneration it causes. Although many theories have been proposed, the cellular reason for this neuropathology remains a mystery. This disease is beginning to be more widely studied because of neuropathological similarities that it shares with AlzheimerТs disease (AD). There are similar endocytic sorting defects in both diseases, and many patients with NPC disease have neurofibrillary tangles indistinguishable from those found in the brains of AD patients. One of the prime suspects in the case of AD neuropathology is the amyloid-beta peptide (AbЁ), an end product of the processing of the amyloid precursor protein and the primary component of plaques found in the brains of AD patients. In its native structure this peptide is thought to be necessary for synaptic signalling, but when overproduced or misprocessed, it tends to aggregate into neurotoxic oligomers. A secreted, misprocessed form of AbЁ also forms senile plaques. The aggregation of AbЁ is not yet altogether understood, but is thought to proceed only after a nucleation or  seeding event. A variety of causes have been shown to trigger the seeding in vitro, including a drop in pH, an increase in AbЁ concentration to a critical max, and the binding of AbЁ to other chemical species. Neuronal death in AD was long thought to be the result of the insoluble senile AbЁ plaques. As these plaques are extremely rare in NPC brains, the AbЁ peptide has largely been ignored as a possible player in NPC neuropathology. Research in the last decade, however, has shifted the paradigm of AbЁ-linked pathology, and senile plaques are no longer thought to play any significant role. Instead, the focus has changed to t"(°6·6№·№Ўh9╡UhО H#VWXYЕ Ж Т LX░Z[╕║*+,+Ї6Ў6°6·6·····················gdО H·6■he soluble AbЁ oligomers, and this has made AbЁ relevant to NPC disease. The research involving AbЁ in NPC disease is still in its beginning stages, but AbЁ oligomers have already been found in NPC cell systems. AbЁ elevation and aggregation in the endosomal system of NPC of mice have also recently been demonstrated, and there is growing evidence that AbЁ might play a significant role in NPC neuropathology. My research currently examines the seeding and aggregation of AbЁ in NPC disease mediated by other chemical species. Atheronal-B is a newly discovered cholesterol oxidation product that has been shown to accelerate the aggregation of AbЁ. This highly reactive cholesterol metabolite, initially found in excised atherosclerotic plaque, is generated wherever cholesterol and inflammation are juxtaposed. This combination of high cholesterol and acute inflammatory reactive oxygen species is unique to only a handful of diseases, one being NPC. Based on high performance liquid chromatography of derivatised lipid extracts from human and murine samples, my research has shown that atheronal-B is significantly elevated in NPC tissues, including the brain. Confocal microscopy studies of a fluorescent atheronal-B analog show that atheronal-B shares similar trafficking patterns with cholesterol and appears to be trapped in the endosomal system in NPC cells. This places it in immediate proximity to elevated levels of AbЁ. I am currently using western blot analysis and fluorescent microscopy to study the atheronal-B-induced formation of AbЁ oligomers in NPC systems. If it can be shown that AbЁ oligomers are involved in the neuropathology of NPC disease, treatments might be employed aimed at reducing the overall AbЁ levels and/or preventing its oligomerisation. 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