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Radiosynthesis of a carbon-11 labeled tetrahydrobenzisoxazole derivative as a new PET probe for γ-secretase imaging in Alzheimer's disease. Appl Radiat Isot 2019; 155:108915. [PMID: 31590101 DOI: 10.1016/j.apradiso.2019.108915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/19/2019] [Accepted: 09/29/2019] [Indexed: 11/23/2022]
Abstract
To develop PET radiotracers for imaging of Alzheimer's disease, a new carbon-11 labeled potent and selective γ-secretase modulator (GSM) has been synthesized. The reference standard tetrahydrobenzisoxazole derivative 8 and its desmethylated precursor 9 were synthesized from cyclohex-2-en-1-one and 3-hydroxy-4-nitrobenzaldehyde in eight and nine steps with 11% and 5% overall chemical yield, respectively. The radiotracer [11C]8 was prepared from its corresponding precursor 9 with [11C]CH3OTf through O-11C-methylation and isolated by RP-HPLC combined with SPE in 45-50% radiochemical yield, based on [11C]CO2 and decay corrected to EOB. The radiochemical purity was >99%, and the molar activity (Am) at EOB was 555-740 GBq/μmol.
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Lee JH, Jahrling JB, Denner L, Dineley KT. Targeting Insulin for Alzheimer’s Disease: Mechanisms, Status and Potential Directions. J Alzheimers Dis 2018; 64:S427-S453. [DOI: 10.3233/jad-179923] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jung Hyun Lee
- Department of Neurology, University of Texas Medical Branch, Galveston, TX, USA
| | - Jordan B. Jahrling
- Department of Neurology, University of Texas Medical Branch, Galveston, TX, USA
| | - Larry Denner
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA
| | - Kelly T. Dineley
- Department of Neurology, University of Texas Medical Branch, Galveston, TX, USA
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Velazquez R, Tran A, Ishimwe E, Denner L, Dave N, Oddo S, Dineley KT. Central insulin dysregulation and energy dyshomeostasis in two mouse models of Alzheimer's disease. Neurobiol Aging 2017; 58:1-13. [PMID: 28688899 PMCID: PMC5819888 DOI: 10.1016/j.neurobiolaging.2017.06.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 05/23/2017] [Accepted: 06/09/2017] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder worldwide. While the causes of AD are not known, several risk factors have been identified. Among these, type two diabetes (T2D), a chronic metabolic disease, is one of the most prevalent risk factors for AD. Insulin resistance, which is associated with T2D, is defined as diminished or absent insulin signaling and is reflected by peripheral blood hyperglycemia and impaired glucose clearance. In this study, we used complementary approaches to probe for peripheral insulin resistance, central nervous system (CNS) insulin sensitivity and energy homeostasis in Tg2576 and 3xTg-AD mice, two widely used animal models of AD. We report that CNS insulin signaling abnormalities are evident months before peripheral insulin resistance. In addition, we find that brain energy metabolism is differentially altered in both mouse models, with 3xTg-AD mice showing more extensive changes. Collectively, our data suggest that early AD may reflect engagement of different signaling networks that influence CNS metabolism, which in turn may alter peripheral insulin signaling.
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Affiliation(s)
- Ramon Velazquez
- Arizona State University-Banner Neurodegenerative Disease Research Center at the Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - An Tran
- Arizona State University-Banner Neurodegenerative Disease Research Center at the Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Egide Ishimwe
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston (UTMB), Galveston, TX, USA
| | - Larry Denner
- Internal Medicine, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston (UTMB), Galveston, TX, USA
| | - Nikhil Dave
- Arizona State University-Banner Neurodegenerative Disease Research Center at the Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Salvatore Oddo
- Arizona State University-Banner Neurodegenerative Disease Research Center at the Biodesign Institute, Arizona State University, Tempe, AZ, USA; School of Life Sciences, Arizona State University, Tempe, AZ, USA.
| | - Kelly T Dineley
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston (UTMB), Galveston, TX, USA.
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Insulin resistance in Alzheimer's disease. Neurobiol Dis 2014; 72 Pt A:92-103. [PMID: 25237037 DOI: 10.1016/j.nbd.2014.09.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 09/02/2014] [Accepted: 09/05/2014] [Indexed: 12/16/2022] Open
Abstract
Insulin is a key hormone regulating metabolism. Insulin binding to cell surface insulin receptors engages many signaling intermediates operating in parallel and in series to control glucose, energy, and lipids while also regulating mitogenesis and development. Perturbations in the function of any of these intermediates, which occur in a variety of diseases, cause reduced sensitivity to insulin and insulin resistance with consequent metabolic dysfunction. Chronic inflammation ensues which exacerbates compromised metabolic homeostasis. Since insulin has a key role in learning and memory as well as directly regulating ERK, a kinase required for the type of learning and memory compromised in early Alzheimer's disease (AD), insulin resistance has been identified as a major risk factor for the onset of AD. Animal models of AD or insulin resistance or both demonstrate that AD pathology and impaired insulin signaling form a reciprocal relationship. Of note are human and animal model studies geared toward improving insulin resistance that have led to the identification of the nuclear receptor and transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ) as an intervention tool for early AD. Strategic targeting of alternate nodes within the insulin signaling network has revealed disease-stage therapeutic windows in animal models that coalesce with previous and ongoing clinical trial approaches. Thus, exploiting the connection between insulin resistance and AD provides powerful opportunities to delineate therapeutic interventions that slow or block the pathogenesis of AD.
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Liu F, Xue ZQ, Deng SH, Kun X, Luo XG, Patrylo PR, Rose GM, Cai H, Struble RG, Cai Y, Yan XX. γ-secretase binding sites in aged and Alzheimer's disease human cerebrum: the choroid plexus as a putative origin of CSF Aβ. Eur J Neurosci 2013; 37:1714-25. [PMID: 23432732 DOI: 10.1111/ejn.12159] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 12/15/2012] [Accepted: 01/17/2013] [Indexed: 01/05/2023]
Abstract
Deposition of β -amyloid (Aβ) peptides, cleavage products of β-amyloid precursor protein (APP) by β-secretase-1 (BACE1) and γ-secretase, is a neuropathological hallmark of Alzheimer's disease (AD). γ-Secretase inhibition is a therapeutical anti-Aβ approach, although changes in the enzyme's activity in AD brain are unclear. Cerebrospinal fluid (CSF) Aβ peptides are thought to derive from brain parenchyma and thus may serve as biomarkers for assessing cerebral amyloidosis and anti-Aβ efficacy. The present study compared active γ-secretase binding sites with Aβ deposition in aged and AD human cerebrum, and explored the possibility of Aβ production and secretion by the choroid plexus (CP). The specific binding density of [(3) H]-L-685,458, a radiolabeled high-affinity γ-secretase inhibitor, in the temporal neocortex and hippocampal formation was similar for AD and control cases with similar ages and post-mortem delays. The CP in post-mortem samples exhibited exceptionally high [(3) H]-L-685,458 binding density, with the estimated maximal binding sites (Bmax) reduced in the AD relative to control groups. Surgically resected human CP exhibited APP, BACE1 and presenilin-1 immunoreactivity, and β-site APP cleavage enzymatic activity. In primary culture, human CP cells also expressed these amyloidogenic proteins and released Aβ40 and Aβ42 into the medium. Overall, our results suggest that γ-secretase activity appears unaltered in the cerebrum in AD and is not correlated with regional amyloid plaque pathology. The CP appears to be a previously unrecognised non-neuronal contributor to CSF Aβ, probably at reduced levels in AD.
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Affiliation(s)
- Fei Liu
- Department of Neurosurgery, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
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Malmquist J, Bernlind A, Sandell J, Ström P, Waldman M. Tritium labeling of a γ-secretase inhibitor and two modulators as in vitro imaging agents. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.1955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jonas Malmquist
- Isotope Chemistry, Screening and Profiling Global DMPK IM; AstraZeneca Research and Development Innovative Medicines; Södertälje; SE-151 85; Sweden
| | - Alexandra Bernlind
- Medicinal Chemistry, CNSP iMed Science Södertälje; AstraZeneca Research and Development Innovative Medicines; Södertälje; SE-151 85; Sweden
| | - Johan Sandell
- Isotope Chemistry, Screening and Profiling Global DMPK IM; AstraZeneca Research and Development Innovative Medicines; Södertälje; SE-151 85; Sweden
| | - Peter Ström
- Isotope Chemistry, Screening and Profiling Global DMPK IM; AstraZeneca Research and Development Innovative Medicines; Södertälje; SE-151 85; Sweden
| | - Magnus Waldman
- Medicinal Chemistry, CNSP iMed Science Södertälje; AstraZeneca Research and Development Innovative Medicines; Södertälje; SE-151 85; Sweden
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Neuronal activity regulates the regional vulnerability to amyloid-β deposition. Nat Neurosci 2011; 14:750-6. [PMID: 21532579 PMCID: PMC3102784 DOI: 10.1038/nn.2801] [Citation(s) in RCA: 673] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 03/11/2011] [Indexed: 12/13/2022]
Abstract
Amyloid-β (Aβ) plaque deposition in specific brain regions is a major pathological hallmark of Alzheimer’fs disease (AD). However, the mechanism underlying the regional vulnerability to Aβ deposition in AD is unknown. Herein, we provide evidence that endogenous neuronal activity regulates the regional concentration of interstitial fluid (ISF) Aβ which drives local Aβ aggregation. Using in vivo microdialysis, we show that ISF Aβ levels in multiple brain regions of APP transgenic mice prior to plaque deposition were commensurate with the degree of subsequent plaque deposition and to the concentration of lactate, a marker of neuronal activity. Furthermore, unilateral vibrissae stimulation increased ISF Aβ, and unilateral vibrissae deprivation decreased ISF Aβ and lactate levels in contralateral barrel cortex. Long term unilateral vibrissae deprivation decreased amyloid plaque formation and growth. Our results suggest a mechanism to account for the vulnerability of specific brain regions to Aβ deposition in AD.
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Grimwood S, Hartig PR. Target site occupancy: Emerging generalizations from clinical and preclinical studies. Pharmacol Ther 2009; 122:281-301. [DOI: 10.1016/j.pharmthera.2009.03.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 01/17/2023]
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Burton CR, Meredith JE, Barten DM, Goldstein ME, Krause CM, Kieras CJ, Sisk L, Iben LG, Polson C, Thompson MW, Lin XA, Corsa J, Fiedler T, Pierdomenico M, Cao Y, Roach AH, Cantone JL, Ford MJ, Drexler DM, Olson RE, Yang MG, Bergstrom CP, McElhone KE, Bronson JJ, Macor JE, Blat Y, Grafstrom RH, Stern AM, Seiffert DA, Zaczek R, Albright CF, Toyn JH. The amyloid-beta rise and gamma-secretase inhibitor potency depend on the level of substrate expression. J Biol Chem 2008; 283:22992-3003. [PMID: 18574238 DOI: 10.1074/jbc.m804175200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The amyloid-beta (Abeta) peptide, which likely plays a key role in Alzheimer disease, is derived from the amyloid-beta precursor protein (APP) through consecutive proteolytic cleavages by beta-site APP-cleaving enzyme and gamma-secretase. Unexpectedly gamma-secretase inhibitors can increase the secretion of Abeta peptides under some circumstances. This "Abeta rise" phenomenon, the same inhibitor causing an increase in Abeta at low concentrations but inhibition at higher concentrations, has been widely observed. Here we show that the Abeta rise depends on the beta-secretase-derived C-terminal fragment of APP (betaCTF) or C99 levels with low levels causing rises. In contrast, the N-terminally truncated form of Abeta, known as "p3," formed by alpha-secretase cleavage, did not exhibit a rise. In addition to the Abeta rise, low betaCTF or C99 expression decreased gamma-secretase inhibitor potency. This "potency shift" may be explained by the relatively high enzyme to substrate ratio under conditions of low substrate because increased concentrations of inhibitor would be necessary to affect substrate turnover. Consistent with this hypothesis, gamma-secretase inhibitor radioligand occupancy studies showed that a high level of occupancy was correlated with inhibition of Abeta under conditions of low substrate expression. The Abeta rise was also observed in rat brain after dosing with the gamma-secretase inhibitor BMS-299897. The Abeta rise and potency shift are therefore relevant factors in the development of gamma-secretase inhibitors and can be evaluated using appropriate choices of animal and cell culture models. Hypothetical mechanisms for the Abeta rise, including the "incomplete processing" and endocytic models, are discussed.
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Affiliation(s)
- Catherine R Burton
- Bristol-Myers Squibb Research and Development, Wallingford, Connecticut 06492, USA
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