| 1. |
- Mattsson, Niklas, 1979, et al.
(författare)
-
BACE1 inhibition induces a specific cerebrospinal fluid β-amyloid pattern that identifies drug effects in the central nervous system.
- 2012
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 7:2
-
Tidskriftsartikel (refereegranskat)abstract
- BACE1 is a key enzyme for amyloid-β (Aβ) production, and an attractive therapeutic target in Alzheimer's disease (AD). Here we report that BACE1 inhibitors have distinct effects on neuronal Aβ metabolism, inducing a unique pattern of secreted Aβ peptides, analyzed in cell media from amyloid precursor protein (APP) transfected cells and in cerebrospinal fluid (CSF) from dogs by immunoprecipitation-mass spectrometry, using several different BACE1 inhibitors. Besides the expected reductions in Aβ1-40 and Aβ1-42, treatment also changed the relative levels of several other Aβ isoforms. In particular Aβ1-34 decreased, while Aβ5-40 increased, and these changes were more sensitive to BACE1 inhibition than the changes in Aβ1-40 and Aβ1-42. The effects on Aβ5-40 indicate the presence of a BACE1 independent pathway of APP degradation. The described CSF Aβ pattern may be used as a pharmacodynamic fingerprint to detect biochemical effects of BACE1-therapies in clinical trials, which might accelerate development of novel therapies.
|
|
| 2. |
- Mattsson, Niklas, 1979, et al.
(författare)
-
Amyloid-β metabolism in Niemann-Pick C disease models and patients.
- 2012
-
Ingår i: Metabolic brain disease. - : Springer Science and Business Media LLC. - 1573-7365 .- 0885-7490. ; 27:4, s. 573-85
-
Tidskriftsartikel (refereegranskat)abstract
- Niemann-Pick type C (NPC) is a progressive neurodegenerative lysosomal disease with altered cellular lipid trafficking. The metabolism of amyloid-β (Aβ) - previously mainly studied in Alzheimer's disease - has been suggested to be altered in NPC. Here we aimed to perform a detailed characterization of metabolic products from the amyloid precursor protein (APP) in NPC models and patients. We used multiple analytical technologies, including immunoassays and immunoprecipitation followed by mass spectrometry (IP-MS) to characterize Aβ peptides and soluble APP fragments (sAPP-α/β) in cell media from pharmacologically (U18666A) and genetically (NPC1 ( -/- ) ) induced NPC cell models, and cerebrospinal fluid (CSF) from NPC cats and human patients. The pattern of Aβ peptides and sAPP-α/β fragments in cell media was differently affected by NPC-phenotype induced by U18666A treatment and by NPC1 ( -/- ) genotype. U18666A treatment increased the secreted media levels of sAPP-α, AβX-40 and AβX-42 and reduced the levels of sAPP-β, Aβ1-40 and Aβ1-42, while IP-MS showed increased relative levels of Aβ5-38 and Aβ5-40 in response to treatment. NPC1 ( -/- ) cells had reduced media levels of sAPP-α and Aβ1-16, and increased levels of sAPP-β. NPC cats had altered CSF distribution of Aβ peptides compared with normal cats. Cats treated with the potential disease-modifying compound 2-hydroxypropyl-β-cyclodextrin had increased relative levels of short Aβ peptides including Aβ1-16 compared with untreated cats. NPC patients receiving β-cyclodextrin had reduced levels over time of CSF Aβ1-42, AβX-38, AβX-40, AβX-42 and sAPP-β, as well as reduced levels of the axonal damage markers tau and phosphorylated tau. We conclude that NPC models have altered Aβ metabolism, but with differences across experimental systems, suggesting that NPC1-loss of function, such as in NPC1 ( -/- ) cells, or NPC1-dysfunction, seen in NPC patients and cats as well as in U18666A-treated cells, may cause subtle but different effects on APP degradation pathways. The preliminary findings from NPC cats suggest that treatment with cyclodextrin may have an impact on APP processing pathways. CSF Aβ, sAPP and tau biomarkers were dynamically altered over time in human NPC patients.
|
|
| 3. |
- Mattsson, Niklas, 1979, et al.
(författare)
-
Converging Pathways of Chromogranin and Amyloid Metabolism in the Brain
- 2010
-
Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 20:4, s. 1039-1048
-
Tidskriftsartikel (refereegranskat)abstract
- Much is unknown regarding the regulation of Alzheimer-related amyloid-beta protein precursor (A beta PP)-processing in the human central nervous system. It has been hypothesized that amyloidogenic A beta PP-processing preferentially occurs in the regulated secretory pathway of neurons. To test this hypothesis we looked for correlations of A beta PP-derived molecules in cerebrospinal fluid (CSF) with chromogranin (Cg) derived peptides, representing the regulated secretion. Patients with Alzheimer's disease (AD, N = 32), multiple sclerosis (MS, N = 50), and healthy controls (N = 70) were enrolled. CSF was analyzed for the amyloid peptides A beta(1-42), A beta(x-42), A beta(x-40), A beta(x-38), alpha-cleaved soluble A beta PP (sA beta PP alpha), beta-cleaved soluble A beta PP (sA beta PP beta), and peptides derived from CgB and SgII (Secretogranin-II, CgC). We investigated CSF levels of the protease BACE1, which processes A beta PP into A beta, in relation to Cg-levels. Finally, we measured Cg levels in cell media from untreated and BACE1-inhibited SH-SY5Y human neuroblastoma cells. CSF Cg levels correlated to sA beta PP and A beta peptides in AD, MS, and controls, and to CSF BACE1. Cell medium from BACE1-inhibited cells had decreased CgB levels. These results suggest that a large part of A beta PP in the human central nervous system is processed in the regulated secretory pathway of neurons.
|
|
| 4. |
- Portelius, Erik, 1977, et al.
(författare)
-
Mass spectrometric characterization of amyloid-β species in the 7PA2 cell model of Alzheimer's disease.
- 2013
-
Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908. ; 33:1, s. 85-93
-
Tidskriftsartikel (refereegranskat)abstract
- The Chinese hamster ovary cell line 7PA2, stably transfected with the 751 amino acid isoform of amyloid-β protein precursor (AβPP) containing the Val → Phe mutation at residue 717, is one of the most used models to study the biochemistry and toxicity of secreted amyloid-β (Aβ) peptides, particularly Aβ oligomers, which are considered to be of relevance to the pathogenesis of Alzheimer's disease. Here, we present a detailed immunochemical and mass spectrometric characterization of primary structures of Aβ peptides secreted by 7PA2 cells. Immunoprecipitation and western blot of 7PA2 cell culture media revealed abundant anti-Aβ immunoreactive bands in the molecular weight range of 4-20 kDa. Mass spectrometric analysis showed that these bands contain several AβPP/Aβ peptides, starting at the N-terminal of the Aβ sequence and extending across the BACE1 cleavage site. Treatment of cells with a BACE1 inhibitor decreased the abundance of the Aβ monomer band by western blot and resulted in lower levels of Aβ1-40, Aβ1-42, and sAβPPβ as measured by ELISA. However, western blot bands thought to represent oligomers of Aβ increased in response to BACE1 inhibition. This increase was paralleled by the emergence of N-terminally truncated Aβ species (Aβ5-40 in particular) and Aβ species that spanned the β-secretase site in AβPP according to mass spectrometric analyses. The formation of these AβPP/Aβ peptides may have implications for the use of the 7PA2 cell line as a model for Aβ pathology. The enzyme(s) responsible for this particular BACE1-independent AβPP-processing remains to be identified.
|
|
| 5. |
- Portelius, Erik, 1977, et al.
(författare)
-
β-site amyloid precursor protein-cleaving enzyme 1(BACE1) inhibitor treatment induces Aβ5-X peptides through alternative amyloid precursor protein cleavage.
- 2014
-
Ingår i: Alzheimer's research & therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 6:5-8
-
Tidskriftsartikel (refereegranskat)abstract
- The β-secretase enzyme, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1), cleaves amyloid precursor protein (APP) in the first step in β-amyloid (Aβ) peptide production. Thus, BACE1 is a key target for candidate disease-modifying treatment of Alzheimer's disease. In a previous exploratory Aβ biomarker study, we found that BACE1 inhibitor treatment resulted in decreased levels of Aβ1-34 together with increased Aβ5-40, suggesting that these Aβ species may be novel pharmacodynamic biomarkers in clinical trials. We have now examined whether the same holds true in humans.
|
|
