| 1. |
- Borgegard, Tomas, et al.
(författare)
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Alzheimers Disease: Presenilin 2-Sparing gamma-Secretase Inhibition Is a Tolerable A beta Peptide-Lowering Strategy
- 2012
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Ingår i: Journal of Neuroscience. - : Society for Neuroscience. - 0270-6474 .- 1529-2401. ; 32:48, s. 17297-17305
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Tidskriftsartikel (refereegranskat)abstract
- gamma-Secretase inhibition represents a major therapeutic strategy for lowering amyloid beta (A beta) peptide production in Alzheimers disease (AD). Progress toward clinical use of gamma-secretase inhibitors has, however, been hampered due to mechanism-based adverse events, primarily related to impairment of Notch signaling. The gamma-secretase inhibitor MRK-560 represents an exception as it is largely tolerable in vivo despite displaying only a small selectivity between A beta production and Notch signaling in vitro. In exploring the molecular basis for the observed tolerability, we show that MRK-560 displays a strong preference for the presenilin 1(PS1) over PS2 subclass of gamma-secretases and is tolerable in wild-type mice but causes dose-dependent Notch-related side effect in PS2-deficient mice at drug exposure levels resulting in a substantial decrease in brain A beta levels. This demonstrates that PS2 plays an important role in mediating essential Notch signaling in several peripheral organs during pharmacological inhibition of PS1 and provide preclinical in vivo proof of concept for PS2-sparing inhibition as a novel, tolerable and efficacious gamma-secretase targeting strategy for AD.
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| 2. |
- Borgegård, Tomas, et al.
(författare)
-
Alzheimer's Disease : Presenilin 2-Sparing γ-Secretase Inhibition Is a Tolerable Aβ Peptide-Lowering Strategy
- 2012
-
Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 32:48, s. 17297-17305
-
Tidskriftsartikel (refereegranskat)abstract
- γ-Secretase inhibition represents a major therapeutic strategy for lowering amyloid β (Aβ) peptide production in Alzheimer's disease (AD). Progress toward clinical use of γ-secretase inhibitors has, however, been hampered due to mechanism-based adverse events, primarily related to impairment of Notch signaling. The γ-secretase inhibitor MRK-560 represents an exception as it is largely tolerable in vivo despite displaying only a small selectivity between Aβ production and Notch signaling in vitro. In exploring the molecular basis for the observed tolerability, we show that MRK-560 displays a strong preference for the presenilin 1 (PS1) over PS2 subclass of γ-secretases and is tolerable in wild-type mice but causes dose-dependent Notch-related side effect in PS2-deficient mice at drug exposure levels resulting in a substantial decrease in brain Aβ levels. This demonstrates that PS2 plays an important role in mediating essential Notch signaling in several peripheral organs during pharmacological inhibition of PS1 and provide preclinical in vivo proof of concept for PS2-sparing inhibition as a novel, tolerable and efficacious γ-secretase targeting strategy for AD.
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| 3. |
- Klintenberg, Rebecka, et al.
(författare)
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Altered extracellular striatal in vivo biotransformation of the opioid neuropeptide dynorphin A(1-17) in the unilateral 6-OHDA rat model of Parkinson's disease
- 2005
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Ingår i: Journal of Mass Spectrometry. - : Wiley. - 1076-5174 .- 1096-9888. ; 40:2, s. 261-270
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Tidskriftsartikel (refereegranskat)abstract
- The in vivo biotransformation of dynorphin A(1-17) (Dyn A) was studied in the striatum of hemiparkinsonian rats by using microdialysis in combination with nanoflow reversed-phase liquid chromatography/electrospray time-of-flight mass spectrometry. The microdialysis probes were implanted into both hemispheres of unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats. Dyn A (10 pmol microl(-1)) was infused through the probes at 0.4 microl min(-1) for 2 h. Samples were collected every 30 min and analyzed by mass spectrometry. The results showed for the first time that there was a difference in the Dyn A biotransformation when comparing the two corresponding sides of the brain. Dyn A metabolites 1-8, 1-16, 5-17, 10-17, 7-10 and 8-10 were detected in the dopamine-depleted striatum but not in the untreated striatum. Dyn A biotransformed fragments found in both hemispheres were N-terminal fragments 1-4, 1-5, 1-6, 1-11, 1-12 and 1-13, C-terminal fragments 2-17, 3-17, 4-17, 7-17 and 8-17 and internal fragments 2-5, 2-10, 2-11, 2-12, and 8-15. The relative levels of these fragments were lower in the dopamine-depleted striatum. The results imply that the extracellular in vivo processing of the dynorphin system is being disturbed in the 6-OHDA-lesion animal model of Parkinson's disease.
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| 4. |
- Klintenberg, Rebecka
(författare)
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Levodopa- and Neuroleptic-Induced Dyskinesias : Studies on Pharmacological Modification and Processing of Opioid Neuropeptides
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dyskinesias or abnormal involuntary movements are a debilitating complication of long-term levodopa treatment of Parkinson’s disease (PD) that is widely experienced and may compromise the efficacy of the drug therapy. Tardive dyskinesia is another important adverse effect seen with antipsychotic drug treatment. The neural mechanisms underlying levodopa- and neuroleptic-induced dyskinesia are not clear and involvement of the endogenous opioid neuropeptide system has been implicated. In this thesis, the role of the opioid system is investigated in models of dyskinesia and PD using behavioral, neurochemical and advanced analytical chemistry techniques. In addition, the motor effects of a new partial dopamine agonist with normalizing properties on both reduced and elevated dopamine transmission are studied and a new model for tardive dyskinesia is presented.Using microdialysis in combination with micro-electrospray mass spectrometry, the in vivo processing of the opioid neuropeptide dynorphin A(1-17) was studied and 32 metabolites were detected in the striatum. Altered in vivo metabolism of the peptide was found in a model of PD with more metabolites formed in the dopamine-depleted striatum. Moreover, dynorphin A(1-17) was differently processed in levodopa-, bromocriptine and saline-treated animals. Levodopa treatment caused an increase in the mRNA expression of the precursor of dynorphin, preproenkephalin-B as well as the precursor of enkephalin, preproenkephalin-A, in all sub-regions of the dopamine-depleted striatum. A non-selective opioid receptor antagonist, naloxone, was found to reduce levodopa-induced dyskinesia with maintained antiparkinsonian response and a normalization of hyperkinesia. Moreover, the new drug GMC1111 showed dopamine stabilizing properties in models of levodopa-induced dyskinesia and PD. This might prove useful in the treatment of PD.Altogether, these results suggest that the endogenous opioid system is involved in the pathophysiology of levodopa-induced dyskinesia.
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| 5. |
- Wanngren, Johanna, et al.
(författare)
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Second generation γ-secretase modulators exhibit different modulation of Notch β and Aβ production.
- 2012
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Ingår i: The Journal of biological chemistry. - 1083-351X. ; 287:39, s. 32640-50
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Tidskriftsartikel (refereegranskat)abstract
- The γ-secretase complex is an appealing drug target when the therapeutic strategy is to alter amyloid-β peptide (Aβ) aggregation in Alzheimer disease. γ-Secretase is directly involved in Aβ formation and determines the pathogenic potential of Aβ by generating the aggregation-prone Aβ42 peptide. Because γ-secretase mediates cleavage of many substrates involved in cell signaling, such as the Notch receptor, it is crucial to sustain these pathways while altering the Aβ secretion. A way of avoiding interference with the physiological function of γ-secretase is to use γ-secretase modulators (GSMs) instead of inhibitors of the enzyme. GSMs modify the Aβ formation from producing the amyloid-prone Aβ42 variant to shorter and less amyloidogenic Aβ species. The modes of action of GSMs are not fully understood, and even though the pharmacology of GSMs has been thoroughly studied regarding Aβ generation, knowledge is lacking about their effects on other substrates, such as Notch. Here, using immunoprecipitation followed by MALDI-TOF MS analysis, we found that two novel, second generation GSMs modulate both Notch β and Aβ production. Moreover, by correlating S3-specific Val-1744 cleavage of Notch intracellular domain (Notch intracellular domain) to total Notch intracellular domain levels using immunocytochemistry, we also demonstrated that Notch intracellular domain is not modulated by the compounds. Interestingly, two well characterized, nonsteroidal anti-inflammatory drugs (nonsteroidal anti-inflammatory drug), R-flurbiprofen and sulindac sulfide, affect only Aβ and not Notch β formation, indicating that second generation GSMs and nonsteroidal anti-inflammatory drug-based GSMs have different modes of action regarding Notch processing.
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| 6. |
- Yngve, Ulrika, et al.
(författare)
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Triazolopyrimidinones as gamma-secretase modulators : structure-activity relationship, modulator profile, and in vivo profiling
- 2013
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Ingår i: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 4:2, s. 422-431
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Tidskriftsartikel (refereegranskat)abstract
- The structure-activity relationship for a series of potent g-secretase modulators based on the 6,7-dihydro4H-[1,2,4]triazolo[1,5-a]pyrimidin-5-one scaffold is described. Furthermore, we report details regarding the modulator profile on A beta processing, as well as in vivo efficacy, for the optimized compounds.
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