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- Laitera, Tiina, et al.
(författare)
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Increased gamma-Secretase Activity in Idiopathic Normal Pressure Hydrocephalus Patients with beta-Amyloid Pathology
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:4, s. e93717-
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Tidskriftsartikel (refereegranskat)abstract
- The potential similarity between the brain pathology of idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer disease (AD) is intriguing and thus further studies focusing on the underlying molecular mechanisms may offer valuable information for differential diagnostics and the development of treatments for iNPH. Here, we investigated beta- and gamma-secretase activities in relation to amyloid-beta (A beta) pathology in the brain tissue samples collected from iNPH and AD patients. beta- and gamma-secretase activities were measured from the frontal cortical biopsies of 26 patients with suspected iNPH as well as post-mortem tissue samples from the inferior temporal cortex of 74 AD patients and eight subjects without neurofibrillary pathology. In iNPH samples with detectable A beta plaques, gamma-secretase activity was significantly increased (similar to 1.6-fold) when compared to iNPH samples without A beta plaques (p=0.009). In the AD samples, statistically significant differences in the gamma-secretase activity were not observed with respect to disease severity (mild, moderate and severe AD according to neurofibrillary pathology). Conversely, beta-secretase activity was unaltered in iNPH samples with or without A beta plaques, while it was significantly increased in relation to disease severity in the AD patients. These results show for the first time increased gamma-secretase but not b-secretase activity in the biopsy samples from the frontal cortex of iNPH patients with AD-like A beta pathology. Conversely, the opposite was observed in these secretase activities in AD patients with respect to neurofibrillary pathology. Despite the resemblances in the A beta pathology, iNPH and AD patients appear to have marked differences in the cellular mechanisms responsible for the production of A beta.
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| 2. |
- Natunen, Teemu, et al.
(författare)
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Effects of NR1H3 Genetic Variation on the Expression of Liver X Receptor alpha and the Progression of Alzheimer's Disease
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:11, s. e80700-
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) has been postulated to involve defects in the clearance of amyloid-beta (A beta). Activation of liver X receptor alpha (LXR alpha) increases the expression of apolipoprotein E (ApoE) as well as cholesterol transporters ABCA1 and ABCG1, leading to augmented clearance of A beta. We have previously shown that the C allele of rs7120118 in the NR1H3 gene encoding LXR alpha reduces the risk of AD. Here, we wanted to assess whether the rs7120118 variation affects the progression of AD and modulates the expression of NR1H3 and its downstream targets APOE, ABCA1 and ABCG1. We utilized tissue samples from the inferior temporal cortex of 87 subjects, which were subdivided according to Braak staging into mild, moderate and severe AD groups on the basis of AD-related neurofibrillary pathology. APOE epsilon 4 allele increased soluble A beta 42 levels in the tissue samples in a dose-dependent manner, but did not affect the expression status of APOE. In contrast, the CC genotype of rs7120118 was underrepresented in the severe group, although this result did not reach statistical significance. Also, patients with the CC genotype of rs7120118 showed significantly decreased soluble A beta 42 levels as compared to the patients with TT genotype. Although the severity of AD did not affect NR1H3 expression, the mRNA levels of NR1H3 among the patients with CT genotype of rs7120118 were significantly increased as compared to the patients with TT genotype. These results suggest that genetic variation in NR1H3 modulates the expression of LXR alpha and the levels of soluble A beta 42.
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