| 1. |
- Jansen, Iris E, et al.
(författare)
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Genome-wide meta-analysis for Alzheimer's disease cerebrospinal fluid biomarkers.
- 2022
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Ingår i: Acta neuropathologica. - : Springer Science and Business Media LLC. - 1432-0533 .- 0001-6322. ; 144:5, s. 821-842
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid-beta 42 (Aβ42) and phosphorylated tau (pTau) levels in cerebrospinal fluid (CSF) reflect core features of the pathogenesis of Alzheimer's disease (AD) more directly than clinical diagnosis. Initiated by the European Alzheimer & Dementia Biobank (EADB), the largest collaborative effort on genetics underlying CSF biomarkers was established, including 31 cohorts with a total of 13,116 individuals (discovery n = 8074; replication n = 5042 individuals). Besides the APOE locus, novel associations with two other well-established AD risk loci were observed; CR1 was shown a locus for Aβ42 and BIN1 for pTau. GMNC and C16orf95 were further identified as loci for pTau, of which the latter is novel. Clustering methods exploring the influence of all known AD risk loci on the CSF protein levels, revealed 4 biological categories suggesting multiple Aβ42 and pTau related biological pathways involved in the etiology of AD. In functional follow-up analyses, GMNC and C16orf95 both associated with lateral ventricular volume, implying an overlap in genetic etiology for tau levels and brain ventricular volume.
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| 2. |
- Kämäläinen, Anna, et al.
(författare)
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GRN Variant rs5848 Reduces Plasma and Brain Levels of Granulin in Alzheimer's Disease Patients.
- 2013
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Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908. ; 33:1, s. 23-7
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Tidskriftsartikel (refereegranskat)abstract
- Genetic variants in the granulin (GRN) gene have been shown to increase the risk of Alzheimer's disease (AD). Here, we report that the A allele of rs5848 in GRN reduces plasma granulin levels in a dose-dependent manner in a clinically-defined AD sample cohort. Similarly, the mRNA levels of granulin were decreased with respect to A allele of rs5848 in the inferior temporal cortex of neuropathologically confirmed AD patients. Our findings suggest that the A allele of rs5848 is functionally relevant by reducing the expression of granulin.
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| 3. |
- 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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| 4. |
- Laitera, Tiina, et al.
(författare)
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The Expression of Transthyretin and Amyloid-beta Protein Precursor is Altered in the Brain of Idiopathic Normal Pressure Hydrocephalus Patients
- 2015
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 48:4, s. 959-968
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Tidskriftsartikel (refereegranskat)abstract
- Background: Idiopathic normal pressure hydrocephalus (iNPH) is a dementing condition in which Alzheimer's disease (AD)related amyloid-beta (A beta) plaques are frequently observed in the neocortex. iNPH patients with prominent A beta pathology show AD-related alterations in amyloid-beta protein precursor (A beta PP) processing resulting from increased gamma-secretase activity. Objectives: Our goal was to assess potential alterations in the global gene expression profile in the brain of iNPH patients as compared to non-demented controls and to evaluate the levels of the identified targets in the cerebrospinal fluid (CSF) of iNPH patients. Methods: The genome-wide expression profile of similar to 35,000 probes was assessed in the RNA samples obtained from 22 iNPH patients and eight non-demented control subjects using a microarray chip. The soluble levels of sA beta PP alpha, sA beta PP beta, and transthyretin (TTR) were measured from the CSF of 102 iNPH patients using ELISA. Results: After correcting the results for multiple testing, significant differences in the expression of TTR and A beta PP were observed between iNPH and control subjects. The mRNA levels of TTR were on average 17-fold lower in iNPH samples compared to control samples. Conversely, the expression level of A beta PP was on average three times higher in iNPH samples as compared to control samples. Interestingly, the expression of beta-secretase (ADAM10) was also increased in iNPH patients. In the lumbar CSF samples, soluble TTR levels showed a significant positive correlation with sA beta PP alpha and sA beta PP beta, but TTR levels did not predict the brain pathology or the shunt response. Conclusions: These findings suggest differences in the expression profile of key factors involved in AD-related cellular events in the brain of iNPH patients.
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| 5. |
- Laiterä, Tiina, et al.
(författare)
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Effects of Alzheimer's Disease-Associated Risk Loci on Amyloid-β Accumulation in the Brain of Idiopathic Normal Pressure Hydrocephalus Patients
- 2017
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 55:3, s. 995-1003
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is a dementing condition featuring characteristic symptoms, ventriculomegaly, and normal or slightly elevated cerebrospinal fluid pressure. In Alzheimer's disease (AD) patients, diffuse aggregates of amyloid-β (Aβ) and neurofibrillary hyperphosphorylated tau are detected in the neocortex of the brain, while similar accumulation of Aβ is also detected in iNPH. Recent genome-wide association studies have identified several novel risk loci for AD, potentially affecting Aβ-related cellular processes. Apart from the apolipoprotein E ɛ4 allele (APOE4), the risk effect of single loci is low, emphasizing the importance of the polygenic risk score approach when assessing the combined effects.OBJECTIVE: To study the effects of AD-associated individual and polygenic risk score of single nucleotide polymorphisms (SNPs) on the accumulation of Aβ in the brain samples of iNPH patients.METHODS: A sample set of frontal cortex biopsies from 188 iNPH patients were divided into two groups according to the Aβ pathology. After the genotyping of the AD-associated risk loci, polygenic risk score was calculated for each iNPH patient and subsequently analyzed in relation to Aβ deposition.RESULTS: Apart from the APOE4, none of the SNPs revealed a statistically significant effect on the accumulation of Aβ in iNPH. Also, the non-APOE4 polygenic risk score did not associate with Aβ deposition.CONCLUSION: Novel AD-associated risk genes have no significant effect on Aβ accumulation in the brain of iNPH patients. However, APOE4 affects the Aβ deposition in the brain of iNPH and AD patients in a similar manner.
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| 6. |
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| 7. |
- Martiskainen, Henna, et al.
(författare)
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Transcriptomics and mechanistic elucidation of Alzheimer's disease risk genes in the brain and in vitro models
- 2015
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 36:2, s. 1221e15-1221e28
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we have assessed the expression and splicing status of genes involved in the pathogenesis or affecting the risk of Alzheimer's disease (AD) in the postmortem inferior temporal cortex samples obtained from 60 subjects with varying degree of AD-related neurofibrillary pathology. These subjects were grouped based on neurofibrillary pathology into 3 groups: Braak stages 0-II, Braak stages III-IV, and Braak stages V-VI. We also examined the right frontal cortical biopsies obtained during life from 22 patients with idiopathic shunt-responding normal pressure hydrocephalus, a disease that displays similar pathologic alterations as seen in AD. These 22 patients were categorized according to dichotomized amyloid-β positive or negative pathology in the biopsies. We observed that the expression of FRMD4A significantly decreased, and the expression of MS4A6A significantly increased in relation to increasing AD-related neurofibrillary pathology. Moreover, the expression of 2 exons in both CLU and TREM2 significantly increased with increase in AD-related neurofibrillary pathology. However, a similar trend toward increased expression in CLU and TREM2 was observed with most of the studied exons, suggesting a global change in the expression rather than altered splicing. Correlation of gene expression with well-established AD-related factors, such as α-, β-, and γ-secretase activities, brain amyloid-β42 levels, and cerebrospinal fluid biomarkers, revealed a positive correlation between β-secretase activity and the expression of TREM2 and BIN1. In expression quantitative trait loci analysis, we did not detect significant effects of the risk alleles on gene expression or splicing. Analysis of the normal pressure hydrocephalus biopsies revealed no differences in the expression or splicing profiles of the studied genes between amyloid-β positive and negative patients. Using the protein-protein interaction-based in vitro pathway analysis tools, we found that downregulation of FRMD4A associated with increased APP-β-secretase interaction, increased amyloid-β40 secretion, and altered phosphorylation of tau. Taken together, our results suggest that the expression of FRMD4A, MS4A6A, CLU, and TREM2 is altered in relation to increasing AD-related neurofibrillary pathology, and that FRMD4A may play a role in amyloidogenic and tau-related pathways in AD. Therefore, investigation of gene expression changes in the brain and effects of the identified genes on disease-associated pathways in vitro may provide mechanistic insights on how alterations in these genes may contribute to AD pathogenesis.
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| 8. |
- 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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| 9. |
- Natunen, Teemu, et al.
(författare)
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Elucidation of the BACE1 Regulating Factor GGA3 in Alzheimer's Disease
- 2013
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 37:1, s. 217-232
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Tidskriftsartikel (refereegranskat)abstract
- Golgi-localized gamma-ear-containing ADP-ribosylation factor-binding protein (GGA3) is a central regulator of trafficking and degradation of BACE1 (beta-site A beta PP-cleaving enzyme), the rate-limiting enzyme in the production of amyloid-beta (A beta) in Alzheimer's disease (AD). Here, we assessed the potential role of GGA3 in AD pathogenesis using independent neuropathological, case-control, and family-based human sample cohorts. Increased BACE1 levels coincided with decreased GGA3 levels and with elevated phosphorylation status of eIF2 alpha-Ser51 in the temporal cortex of AD patients as compared to age-matched controls. Severity of the disease did not alter mRNA or protein levels of GGA3 in the inferior temporal cortex of AD patients, while a positive correlation between GGA3 and the levels of total, but not phosphorylated, tau was observed. Genetically, we did not observe consistent evidence for association between AD risk and common GGA3 polymorphisms across a number of independent sample cohorts. However, a nominally significant association was observed with rs2242230 (p < 0.05) among the Finnish case-control cohort. Accordingly, mRNA and protein levels of GGA3 in the inferior temporal cortex of AD patients did not significantly correlate with rs2242230 genotype status. While the present study indicates that GGA3 is involved in the cellular processes relevant for AD pathogenesis, the genetic data do not support the idea that common GGA3 polymorphisms would contribute to AD risk.
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| 10. |
- Salminen, Antero, et al.
(författare)
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Emerging role of p62/sequestosome-1 in the pathogenesis of Alzheimer's disease
- 2012
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Ingår i: Progress in Neurobiology. - : Elsevier BV. - 0301-0082 .- 1873-5118. ; 96:1, s. 87-95
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Forskningsöversikt (refereegranskat)abstract
- The p62/sequestosome-1 is a multifunctional protein containing several protein-protein interaction domains. Through these interactions p62 is involved in the regulation of cellular signaling and protein trafficking, aggregation and degradation. p62 protein can bind through its UBA motif to ubiquitinated proteins and control their aggregation and degradation via either autophagy or proteasomes. p62 protein has been reported to be seen in association with the intracellular inclusions in primary and secondary tauopathies, α-synucleinopathies and other neurodegenerative brain disorders displaying inclusions with misfolded proteins. In Alzheimer's disease (AD), p62 protein is associated with neurofibrillary tangles composed primarily of hyperphosphorylated tau protein and ubiquitin. Increasing evidence indicates that p62 has an important role in the degradation of tau protein. The lack of p62 protein expression provokes the tau pathology in mice. Recent studies have demonstrated that the p62 gene expression and cytoplasmic p62 protein levels are significantly reduced in the frontal cortex of AD patients. Decline in the level of p62 protein can disturb the signaling pathways of Nrf2, cyclic AMP and NF-κB and in that way increase oxidative stress and impair neuronal survival. We will review here the molecular and functional characteristics of p62 protein and outline its potential role in the regulation of Alzheimer's pathogenesis.
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