26
|
Nuber S, Chung CY, Tardiff DF, Bechade PA, McCaffery TD, Shimanaka K, Choi J, Chang B, Raja W, Neves E, Burke C, Jiang X, Xu P, Khurana V, Dettmer U, Fanning S, Rhodes KJ, Selkoe DJ, Scannevin RH. Correction to: A Brain-Penetrant Stearoyl-CoA Desaturase Inhibitor Reverses α-Synuclein Toxicity. Neurotherapeutics 2022; 19:1434. [PMID: 35792968 PMCID: PMC9587197 DOI: 10.1007/s13311-022-01268-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
|
27
|
Liu L, Cai Y, Lauro BM, Meunier AL, Chhatwal J, Selkoe DJ. Generation and application of semi-synthetic p-Tau181 calibrator for immunoassay calibration. Biochem Biophys Res Commun 2022; 611:85-90. [PMID: 35483223 DOI: 10.1016/j.bbrc.2022.04.077] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/08/2022] [Accepted: 04/17/2022] [Indexed: 12/28/2022]
Abstract
Evidence suggests that plasma levels of tau protein phosphorylated at specific residues such as p-T181, p-T217, and p-T231 can be used as biomarkers for Alzheimer's disease (AD) diagnosis and prognosis. Accurate tools to calibrate immunoassays (calibrators) to precisely detect phosphorylated residues on tau protein will provide important gains in reliability and specificity. This study sought to establish a method to generate those accurate calibrators. We generated a semi-synthetic (chimeric) p-Tau181 calibrator by coupling a recombinant tau fragment (residues 1-174) with a synthetic peptide containing a single phosphorylated residue (p-T181) via thioester bond formation. The generation of a semi-synthetic protein containing both the N-terminal region of tau and the pT181 epitope was demonstrated by mobility shift assays using CBB staining and immunoblotting with N-terminal and pT181-specific antibodies. p-Tau 181 assays performed with the novel calibrator on multiple platforms revealed LLoQs as low as 0.14 pg/ml. Our facile and inexpensive method generates a semi-synthetic tau pT181 calibrator suitable for different immunoassay platforms. The same method can easily be adapted to other AD-relevant phospho-epitopes such as pT217 and pT231.
Collapse
|
28
|
Nuber S, Chung CY, Tardiff DF, Bechade PA, McCaffery TD, Shimanaka K, Choi J, Chang B, Raja W, Neves E, Burke C, Jiang X, Xu P, Khurana V, Dettmer U, Fanning S, Rhodes KJ, Selkoe DJ, Scannevin RH. A Brain-Penetrant Stearoyl-CoA Desaturase Inhibitor Reverses α-Synuclein Toxicity. Neurotherapeutics 2022; 19:1018-1036. [PMID: 35445353 PMCID: PMC9294123 DOI: 10.1007/s13311-022-01199-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2022] [Indexed: 12/01/2022] Open
Abstract
Increasing evidence has shown that Parkinson's disease (PD) impairs midbrain dopaminergic, cortical and other neuronal subtypes in large part due to the build-up of lipid- and vesicle-rich α-synuclein (αSyn) cytotoxic inclusions. We previously identified stearoyl-CoA desaturase (SCD) as a potential therapeutic target for synucleinopathies. A brain-penetrant SCD inhibitor, YTX-7739, was developed and has entered Phase 1 clinical trials. Here, we report the efficacy of YTX-7739 in reversing pathological αSyn phenotypes in various in vitro and in vivo PD models. In cell-based assays, YTX-7739 decreased αSyn-mediated neuronal death, reversed the abnormal membrane interaction of amplified E46K ("3K") αSyn, and prevented pathological phenotypes in A53T and αSyn triplication patient-derived neurospheres, including dysregulated fatty acid profiles and pS129 αSyn accumulation. In 3K PD-like mice, YTX-7739 crossed the blood-brain barrier, decreased unsaturated fatty acids, and prevented progressive motor deficits. Both YTX-7739 treatment and decreasing SCD activity through deletion of one copy of the SCD1 gene (SKO) restored the physiological αSyn tetramer-to-monomer ratio, dopaminergic integrity, and neuronal survival in 3K αSyn mice. YTX-7739 efficiently reduced pS129 + and PK-resistant αSyn in both human wild-type αSyn and 3K mutant mice similar to the level of 3K-SKO. Together, these data provide further validation of SCD as a PD therapeutic target and YTX-7739 as a clinical candidate for treating human α-synucleinopathies.
Collapse
|
29
|
Rimmele TS, Li S, Andersen JV, Westi EW, Rotenberg A, Wang J, Aldana BI, Selkoe DJ, Aoki CJ, Dulla CG, Rosenberg PA. Neuronal Loss of the Glutamate Transporter GLT-1 Promotes Excitotoxic Injury in the Hippocampus. Front Cell Neurosci 2022; 15:788262. [PMID: 35035352 PMCID: PMC8752461 DOI: 10.3389/fncel.2021.788262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/08/2021] [Indexed: 12/26/2022] Open
Abstract
GLT-1, the major glutamate transporter in the mammalian central nervous system, is expressed in presynaptic terminals that use glutamate as a neurotransmitter, in addition to astrocytes. It is widely assumed that glutamate homeostasis is regulated primarily by glutamate transporters expressed in astrocytes, leaving the function of GLT-1 in neurons relatively unexplored. We generated conditional GLT-1 knockout (KO) mouse lines to understand the cell-specific functions of GLT-1. We found that stimulus-evoked field extracellular postsynaptic potentials (fEPSPs) recorded in the CA1 region of the hippocampus were normal in the astrocytic GLT-1 KO but were reduced and often absent in the neuronal GLT-1 KO at 40 weeks. The failure of fEPSP generation in the neuronal GLT-1 KO was also observed in slices from 20 weeks old mice but not consistently from 10 weeks old mice. Using an extracellular FRET-based glutamate sensor, we found no difference in stimulus-evoked glutamate accumulation in the neuronal GLT-1 KO, suggesting a postsynaptic cause of the transmission failure. We hypothesized that excitotoxicity underlies the failure of functional recovery of slices from the neuronal GLT-1 KO. Consistent with this hypothesis, the non-competitive NMDA receptor antagonist MK801, when present in the ACSF during the recovery period following cutting of slices, promoted full restoration of fEPSP generation. The inclusion of an enzymatic glutamate scavenging system in the ACSF conferred partial protection. Excitotoxicity might be due to excess release or accumulation of excitatory amino acids, or to metabolic perturbation resulting in increased vulnerability to NMDA receptor activation. Previous studies have demonstrated a defect in the utilization of glutamate by synaptic mitochondria and aspartate production in the synGLT-1 KO in vivo, and we found evidence for similar metabolic perturbations in the slice preparation. In addition, mitochondrial cristae density was higher in synaptic mitochondria in the CA1 region in 20–25 weeks old synGLT-1 KO mice in the CA1 region, suggesting compensation for loss of axon terminal GLT-1 by increased mitochondrial efficiency. These data suggest that GLT-1 expressed in presynaptic terminals serves an important role in the regulation of vulnerability to excitotoxicity, and this regulation may be related to the metabolic role of GLT-1 expressed in glutamatergic axon terminals.
Collapse
|
30
|
Stern AM, Liu L, Jin S, Liu W, Meunier AL, Ericsson M, Miller MB, Batson M, Sun T, Kathuria S, Reczek D, Pradier L, Selkoe DJ. OUP accepted manuscript. Brain 2022; 145:2528-2540. [PMID: 35084489 PMCID: PMC9337809 DOI: 10.1093/brain/awac023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/01/2021] [Accepted: 12/20/2021] [Indexed: 11/26/2022] Open
Abstract
Aqueously soluble oligomers of amyloid-β peptide may be the principal neurotoxic forms of amyloid-β in Alzheimer’s disease, initiating downstream events that include tau hyperphosphorylation, neuritic/synaptic injury, microgliosis and neuron loss. Synthetic oligomeric amyloid-β has been studied extensively, but little is known about the biochemistry of natural oligomeric amyloid-β in human brain, even though it is more potent than simple synthetic peptides and comprises truncated and modified amyloid-β monomers. We hypothesized that monoclonal antibodies specific to neurotoxic oligomeric amyloid-β could be used to isolate it for further study. Here we report a unique human monoclonal antibody (B24) raised against synthetic oligomeric amyloid-β that potently prevents Alzheimer’s disease brain oligomeric amyloid-β-induced impairment of hippocampal long-term potentiation. B24 binds natural and synthetic oligomeric amyloid-β and a subset of amyloid plaques, but only in the presence of Ca2+. The amyloid-β N terminus is required for B24 binding. Hydroxyapatite chromatography revealed that natural oligomeric amyloid-β is highly avid for Ca2+. We took advantage of the reversible Ca2+-dependence of B24 binding to perform non-denaturing immunoaffinity isolation of oligomeric amyloid-β from Alzheimer’s disease brain-soluble extracts. Unexpectedly, the immunopurified material contained amyloid fibrils visualized by electron microscopy and amenable to further structural characterization. B24-purified human oligomeric amyloid-β inhibited mouse hippocampal long-term potentiation. These findings identify a calcium-dependent method for purifying bioactive brain oligomeric amyloid-β, at least some of which appears fibrillar.
Collapse
|
31
|
Lagomarsino VN, Pearse RV, Liu L, Hsieh YC, Fernandez MA, Vinton EA, Paull D, Felsky D, Tasaki S, Gaiteri C, Vardarajan B, Lee H, Muratore CR, Benoit CR, Chou V, Fancher SB, He A, Merchant JP, Duong DM, Martinez H, Zhou M, Bah F, Vicent MA, Stricker JMS, Xu J, Dammer EB, Levey AI, Chibnik LB, Menon V, Seyfried NT, De Jager PL, Noggle S, Selkoe DJ, Bennett DA, Young-Pearse TL. Stem cell-derived neurons reflect features of protein networks, neuropathology, and cognitive outcome of their aged human donors. Neuron 2021; 109:3402-3420.e9. [PMID: 34473944 DOI: 10.1016/j.neuron.2021.08.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/30/2021] [Accepted: 08/05/2021] [Indexed: 11/26/2022]
Abstract
We have generated a controlled and manipulable resource that captures genetic risk for Alzheimer's disease: iPSC lines from 53 individuals coupled with RNA and proteomic profiling of both iPSC-derived neurons and brain tissue of the same individuals. Data collected for each person include genome sequencing, longitudinal cognitive scores, and quantitative neuropathology. The utility of this resource is exemplified here by analyses of neurons derived from these lines, revealing significant associations between specific Aβ and tau species and the levels of plaque and tangle deposition in the brain and, more importantly, with the trajectory of cognitive decline. Proteins and networks are identified that are associated with AD phenotypes in iPSC neurons, and relevant associations are validated in brain. The data presented establish this iPSC collection as a resource for investigating person-specific processes in the brain that can aid in identifying and validating molecular pathways underlying AD.
Collapse
|
32
|
|
33
|
Liu L, Kwak H, Lawton TL, Jin SX, Meunier AL, Dang Y, Ostaszewski B, Pietras AC, Stern AM, Selkoe DJ. An ultra-sensitive immunoassay detects and quantifies soluble Aβ oligomers in human plasma. Alzheimers Dement 2021; 18:1186-1202. [PMID: 34550630 DOI: 10.1002/alz.12457] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/02/2021] [Accepted: 07/30/2021] [Indexed: 01/10/2023]
Abstract
INTRODUCTION Evidence strongly suggests that soluble oligomers of amyloid beta protein (oAβ) help initiate the pathogenic cascade of Alzheimer's disease (AD). To date, there have been no validated assays specific for detecting and quantifying oAβ in human blood. METHODS We developed an ultrasensitive oAβ immunoassay using a novel capture antibody (71A1) with N-terminal antibody 3D6 for detection that specifically quantifies soluble oAβ in the human brain, cerebrospinal fluid (CSF), and plasma. RESULTS Two new antibodies (71A1; 1G5) are oAβ-selective, label Aβ plaques in non-fixed AD brain sections, and potently neutralize the synaptotoxicity of AD brain-derived oAβ. The 71A1/3D6 assay showed excellent dilution linearity in CSF and plasma without matrix effects, good spike recovery, and specific immunodepletion. DISCUSSION We have created a sensitive, high throughput, and inexpensive method to quantify synaptotoxic oAβ in human plasma for analyzing large cohorts of aged and AD subjects to assess the dynamics of this key pathogenic species and response to therapy.
Collapse
|
34
|
|
35
|
Aisen PS, Cummings J, Doody R, Kramer L, Salloway S, Selkoe DJ, Sims J, Sperling RA, Vellas B. The Future of Anti-Amyloid Trials. JPAD-JOURNAL OF PREVENTION OF ALZHEIMERS DISEASE 2021; 7:146-151. [PMID: 32463066 DOI: 10.14283/jpad.2020.24] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The termination of many clinical trials of amyloid-targeting therapies for the treatment of Alzheimer's disease (AD) has had a major impact on the AD clinical research enterprise. However, positive signals in recent studies have reinvigorated support for the amyloid hypothesis and amyloid-targeting strategies. In December 2019, the EU-US Clinical Trials on Alzheimer's Disease (CTAD) Task Force met to share learnings from these studies in order to inform future trials and promote the development of effective AD treatments. Critical factors that have emerged in studies of anti-amyloid monoclonal antibody therapies include developing a better understanding of the specific amyloid species targeted by different antibodies, advancing our insight into the mechanism by which those antibodies may reduce pathology, implementing more comprehensive repertoires of biomarkers into trials, and identifying appropriate doses. Studies suggest that Amyloid-Related Imaging Abnormalities - effusion type (ARIA-E) are a manageable safety concern and that caution should be exercised before terminating studies based on interim analyses. The Task Force concluded that opportunities for developing effective treatments include developing new biomarkers, intervening in early stages of disease, and use of combination therapies.
Collapse
|
36
|
Selkoe DJ. Editorial: A Is for Amyloid. JPAD-JOURNAL OF PREVENTION OF ALZHEIMERS DISEASE 2021; 7:140-141. [PMID: 32463063 PMCID: PMC7182734 DOI: 10.14283/jpad.2020.27] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
37
|
Liu L, Lauro BM, Wolfe MS, Selkoe DJ. Hydrophilic loop 1 of Presenilin-1 and the APP GxxxG transmembrane motif regulate γ-secretase function in generating Alzheimer-causing Aβ peptides. J Biol Chem 2021; 296:100393. [PMID: 33571524 PMCID: PMC7961089 DOI: 10.1016/j.jbc.2021.100393] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/22/2021] [Accepted: 02/04/2021] [Indexed: 02/06/2023] Open
Abstract
γ-Secretase is responsible for the proteolysis of amyloid precursor protein (APP) into amyloid-beta (Aβ) peptides, which are centrally implicated in the pathogenesis of Alzheimer’s disease (AD). The biochemical mechanism of how processing by γ-secretase is regulated, especially as regards the interaction between enzyme and substrate, remains largely unknown. Here, mutagenesis reveals that the hydrophilic loop-1 (HL-1) of presenilin-1 (PS1) is critical for both γ-secretase step-wise cleavages (processivity) and its allosteric modulation by heterocyclic γ-modulatory compounds. Systematic mutagenesis of HL-1, including all of its familial AD mutations and additional engineered variants, and quantification of the resultant Aβ products show that HL-1 is necessary for proper sequential γ-secretase processivity. We identify Y106, L113, and Y115 in HL-1 as key targets for heterocyclic γ-secretase modulators (GSMs) to stimulate processing of pathogenic Aβ peptides. Further, we confirm that the GxxxG domain in the APP transmembrane region functions as a critical substrate motif for γ-secretase processivity: a G29A substitution in APP-C99 mimics the beneficial effects of GSMs. Together, these findings provide a molecular basis for the structural regulation of γ-processivity by enzyme and substrate, facilitating the rational design of new GSMs that lower AD-initiating amyloidogenic Aβ peptides.
Collapse
|
38
|
Chhatwal JP, Schultz AP, Dang Y, Ostaszewski B, Liu L, Yang H, Johnson KA, Sperling RA, Selkoe DJ. Plasma levels of an N‐terminal tau fragment are highly associated with future cognitive decline and neurodegeneration in clinically normal elderly. Alzheimers Dement 2020. [DOI: 10.1002/alz.045261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
39
|
Stern A, Liu W, Jin M, Walsh DM, Selkoe DJ. Transcriptomic correlates of neurite degeneration due to human brain‐derived Aβ and protection by clinical anti‐Aβ antibodies. Alzheimers Dement 2020. [DOI: 10.1002/alz.043057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
40
|
Liu L, Stern A, Dang Y, Ostaszewski B, Chhatwal JP, Selkoe DJ. Predicting development of AD clinical symptoms and their progression through a collection of novel plasma Aβ immunoassays. Alzheimers Dement 2020. [DOI: 10.1002/alz.043670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
41
|
Chhatwal JP, Schultz AP, Dang Y, Ostaszewski B, Liu L, Yang HS, Johnson KA, Sperling RA, Selkoe DJ. Plasma N-terminal tau fragment levels predict future cognitive decline and neurodegeneration in healthy elderly individuals. Nat Commun 2020; 11:6024. [PMID: 33247134 PMCID: PMC7695712 DOI: 10.1038/s41467-020-19543-w] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/12/2020] [Indexed: 02/06/2023] Open
Abstract
The availability of blood-based assays detecting Alzheimer's disease (AD) pathology should greatly accelerate AD therapeutic development and improve clinical care. This is especially true for markers that capture the risk of decline in pre-symptomatic stages of AD, as this would allow one to focus interventions on participants maximally at risk and at a stage prior to widespread synapse loss and neurodegeneration. Here we quantify plasma concentrations of an N-terminal fragment of tau (NT1) in a large, well-characterized cohort of clinically normal elderly who were followed longitudinally. Plasma NT1 levels at study entry (when all participants were unimpaired) were highly predictive of future cognitive decline, pathological tau accumulation, neurodegeneration, and transition to a diagnosis of MCI/AD. These predictive effects were particularly strong in participants with even modestly elevated brain β-amyloid burden at study entry, suggesting plasma NT1 levels capture very early cognitive, pathologic and neurodegenerative changes along the AD trajectory.
Collapse
|
42
|
Ho GPH, Ramalingam N, Imberdis T, Wilkie EC, Dettmer U, Selkoe DJ. Upregulation of Cellular Palmitoylation Mitigates α-Synuclein Accumulation and Neurotoxicity. Mov Disord 2020; 36:348-359. [PMID: 33103814 DOI: 10.1002/mds.28346] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 09/29/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Synucleinopathies, including Parkinson's disease (PD), are characterized by α-synuclein (αS) cytoplasmic inclusions. αS-dependent vesicle-trafficking defects are important in PD pathogenesis, but their mechanisms are not well understood. Protein palmitoylation, post-translational addition of the fatty acid palmitate to cysteines, promotes trafficking by anchoring specific proteins to the vesicle membrane. αS itself cannot be palmitoylated as it lacks cysteines, but it binds to membranes, where palmitoylation occurs, via an amphipathic helix. We hypothesized that abnormal αS membrane-binding impairs trafficking by disrupting palmitoylation. Accordingly, we investigated the therapeutic potential of increasing cellular palmitoylation. OBJECTIVES We asked whether upregulating palmitoylation by inhibiting the depalmitoylase acyl-protein-thioesterase-1 (APT1) ameliorates pathologic αS-mediated cellular phenotypes and sought to identify the mechanism. METHODS Using human neuroblastoma cells, rat neurons, and iPSC-derived PD patient neurons, we examined the effects of pharmacologic and genetic downregulation of APT1 on αS-associated phenotypes. RESULTS APT1 inhibition or knockdown decreased αS cytoplasmic inclusions, reduced αS serine-129 phosphorylation (a PD neuropathological marker), and protected against αS-dependent neurotoxicity. We identified the APT1 substrate microtubule-associated-protein-6 (MAP6), which binds to vesicles in a palmitoylation-dependent manner, as a key mediator of these effects. Mechanistically, we found that pathologic αS accelerated palmitate turnover on MAP6, suggesting that APT1 inhibition corrects a pathological αS-dependent palmitoylation deficit. We confirmed the disease relevance of this mechanism by demonstrating decreased MAP6 palmitoylation in neurons from αS gene triplication patients. CONCLUSIONS Our findings demonstrate a novel link between the fundamental process of palmitoylation and αS pathophysiology. Upregulating palmitoylation represents an unexplored therapeutic strategy for synucleinopathies. © 2020 International Parkinson and Movement Disorder Society.
Collapse
|
43
|
Nuber S, Nam AY, Rajsombath MM, Cirka H, Hronowski X, Wang J, Hodgetts K, Kalinichenko LS, Müller CP, Lambrecht V, Winkler J, Weihofen A, Imberdis T, Dettmer U, Fanning S, Selkoe DJ. A Stearoyl-Coenzyme A Desaturase Inhibitor Prevents Multiple Parkinson Disease Phenotypes in α-Synuclein Mice. Ann Neurol 2020; 89:74-90. [PMID: 32996158 PMCID: PMC7756464 DOI: 10.1002/ana.25920] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 09/25/2020] [Accepted: 09/25/2020] [Indexed: 12/20/2022]
Abstract
Objective Parkinson disease (PD) has useful symptomatic treatments that do not slow the neurodegenerative process, and no significant disease‐modifying treatments are approved. A key therapeutic target in PD is α‐synuclein (αS), which is both genetically implicated and accumulates in Lewy bodies rich in vesicles and other lipid membranes. Reestablishing αS homeostasis is a central goal in PD. Based on previous lipidomic analyses, we conducted a mouse trial of a stearoyl–coenzyme A desaturase (SCD) inhibitor (“5b”) that prevented αS‐positive vesicular inclusions and cytotoxicity in cultured human neurons. Methods Oral dosing and brain activity of 5b were established in nontransgenic mice. 5b in drinking water was given to mice expressing wild‐type human αS (WT) or an amplified familial PD αS mutation (E35K + E46K + E61K ["3K"]) beginning near the onset of nigral and cortical neurodegeneration and the robust PD‐like motor syndrome in 3K. Motor phenotypes, brain cytopathology, and SCD‐related lipid changes were quantified in 5b‐ versus placebo‐treated mice. Outcomes were compared to effects of crossing 3K to SCD1−/− mice. Results 5b treatment reduced αS hyperphosphorylation in E46K‐expressing human neurons, in 3K neural cultures, and in both WT and 3K αS mice. 5b prevented subtle gait deficits in WT αS mice and the PD‐like resting tremor and progressive motor decline of 3K αS mice. 5b also increased αS tetramers and reduced proteinase K‐resistant lipid‐rich aggregates. Similar benefits accrued from genetically deleting 1 SCD allele, providing target validation. Interpretation Prolonged reduction of brain SCD activity prevented PD‐like neuropathology in multiple PD models. Thus, an orally available SCD inhibitor potently ameliorates PD phenotypes, positioning this approach to treat human α‐synucleinopathies. ANN NEUROL 2021;89:74–90
Collapse
|
44
|
Lauwers E, Lalli G, Brandner S, Collinge J, Compernolle V, Duyckaerts C, Edgren G, Haïk S, Hardy J, Helmy A, Ivinson AJ, Jaunmuktane Z, Jucker M, Knight R, Lemmens R, Lin IC, Love S, Mead S, Perry VH, Pickett J, Poppy G, Radford SE, Rousseau F, Routledge C, Schiavo G, Schymkowitz J, Selkoe DJ, Smith C, Thal DR, Theys T, Tiberghien P, van den Burg P, Vandekerckhove P, Walton C, Zaaijer HL, Zetterberg H, De Strooper B. Potential human transmission of amyloid β pathology: surveillance and risks. Lancet Neurol 2020; 19:872-878. [PMID: 32949547 DOI: 10.1016/s1474-4422(20)30238-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/22/2020] [Accepted: 05/28/2020] [Indexed: 01/05/2023]
Abstract
Studies in experimental animals show transmissibility of amyloidogenic proteins associated with prion diseases, Alzheimer's disease, Parkinson's disease, and other neurodegenerative diseases. Although these data raise potential concerns for public health, convincing evidence for human iatrogenic transmission only exists for prions and amyloid β after systemic injections of contaminated growth hormone extracts or dura mater grafts derived from cadavers. Even though these procedures are now obsolete, some reports raise the possibility of iatrogenic transmission of amyloid β through putatively contaminated neurosurgical equipment. Iatrogenic transmission of amyloid β might lead to amyloid deposition in the brain parenchyma and blood vessel walls, potentially resulting in cerebral amyloid angiopathy after several decades. Cerebral amyloid angiopathy can cause life-threatening brain haemorrhages; yet, there is no proof that the transmission of amyloid β can also lead to Alzheimer's dementia. Large, long-term epidemiological studies and sensitive, cost-efficient tools to detect amyloid are needed to better understand any potential routes of amyloid β transmission and to clarify whether other similar proteopathic seeds, such as tau or α-synuclein, can also be transferred iatrogenically.
Collapse
|
45
|
Walsh DM, Selkoe DJ. Amyloid β-protein and beyond: the path forward in Alzheimer's disease. Curr Opin Neurobiol 2020; 61:116-124. [PMID: 32197217 DOI: 10.1016/j.conb.2020.02.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/30/2020] [Accepted: 02/05/2020] [Indexed: 12/13/2022]
Abstract
Basic research on the biological mechanism of Alzheimer's disease has focused for decades on the age-related aggregation of the amyloid β-protein and its apparent downstream effects on microglia, astrocytes and neurons, including the posttranslational modification of the tau protein that seems necessary for symptom expression. Here, we discuss the highly challenging process of developing disease-modifying therapies and highlight several key areas of current research that are progressing in exciting directions. We conclude that further deep molecular analyses of the disease, including the mechanisms of β-amyloidosis, will enable more effective clinical trials and ultimately achieve the progress that our patients so deserve.
Collapse
|
46
|
Li S, Selkoe DJ. A mechanistic hypothesis for the impairment of synaptic plasticity by soluble Aβ oligomers from Alzheimer's brain. J Neurochem 2020; 154:583-597. [PMID: 32180217 DOI: 10.1111/jnc.15007] [Citation(s) in RCA: 131] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 12/18/2022]
Abstract
It is increasingly accepted that early cognitive impairment in Alzheimer's disease results in considerable part from synaptic dysfunction caused by the accumulation of a range of oligomeric assemblies of amyloid β-protein (Aβ). Most studies have used synthetic Aβ peptides to explore the mechanisms of memory deficits in rodent models, but recent work suggests that Aβ assemblies isolated from human (AD) brain tissue are far more potent and disease-relevant. Although reductionist experiments show Aβ oligomers to impair synaptic plasticity and neuronal viability, the responsible mechanisms are only partly understood. Glutamatergic receptors, GABAergic receptors, nicotinic receptors, insulin receptors, the cellular prion protein, inflammatory mediators, and diverse signaling pathways have all been suggested. Studies using AD brain-derived soluble Aβ oligomers suggest that only certain bioactive forms (principally small, diffusible oligomers) can disrupt synaptic plasticity, including by binding to plasma membranes and changing excitatory-inhibitory balance, perturbing mGluR, PrP, and other neuronal surface proteins, down-regulating glutamate transporters, causing glutamate spillover, and activating extrasynaptic GluN2B-containing NMDA receptors. We synthesize these emerging data into a mechanistic hypothesis for synaptic failure in Alzheimer's disease that can be modified as new knowledge is added and specific therapeutics are developed.
Collapse
|
47
|
Mengel D, Liu W, Glynn RJ, Selkoe DJ, Strydom A, Lai F, Rosas HD, Torres A, Patsiogiannis V, Skotko B, Walsh DM. Dynamics of plasma biomarkers in Down syndrome: the relative levels of Aβ42 decrease with age, whereas NT1 tau and NfL increase. ALZHEIMERS RESEARCH & THERAPY 2020; 12:27. [PMID: 32192521 PMCID: PMC7081580 DOI: 10.1186/s13195-020-00593-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/06/2020] [Indexed: 11/12/2022]
Abstract
Background Down syndrome (DS) is the most common genetic cause of Alzheimer’s disease (AD), but diagnosis of AD in DS is challenging due to the intellectual disability which accompanies DS. When disease-modifying agents for AD are approved, reliable biomarkers will be required to identify when and how long people with DS should undergo treatment. Three cardinal neuropathological features characterize AD, and AD in DS—Aβ amyloid plaques, tau neurofibrillary tangles, and neuronal loss. Here, we quantified plasma biomarkers of all 3 neuropathological features in a large cohort of people with DS aged from 3 months to 68 years. Our primary aims were (1) to assess changes in the selected plasma biomarkers in DS across age, and (2) to compare biomarkers measured in DS plasma versus age- and sex-matched controls. Methods Using ultra-sensitive single molecule array (Simoa) assays, we measured 3 analytes (Aβ42, NfL, and tau) in plasmas of 100 individuals with DS and 100 age- and sex-matched controls. Tau was measured using an assay (NT1) which detects forms of tau containing at least residues 6–198. The stability of the 3 analytes was established using plasma from ten healthy volunteers collected at 6 intervals over a 5-day period. Results High Aβ42 and NT1 tau and low NfL were observed in infants. Across all ages, Aβ42 levels were higher in DS than controls. Levels of Aβ42 decreased with age in both DS and controls, but this decrease was greater in DS than controls and became prominent in the third decade of life. NT1 tau fell in adolescents and young adults, but increased in older individuals with DS. NfL levels were low in infants, children, adolescents, and young adults, but thereafter increased in DS compared to controls. Conclusions High levels of Aβ42 and tau in both young controls and DS suggest these proteins are produced by normal physiological processes, whereas the changes seen in later life are consistent with emergence of pathological alterations. These plasma biomarker results are in good agreement with prior neuropathology studies and indicate that the third and fourth decades (i.e., 20 to 40 years of age) of life are pivotal periods during which AD processes manifest in DS. Application of the assays used here to longitudinal studies of individuals with DS aged 20 to 50 years of age should further validate the use of these biomarkers, and in time may allow identification and monitoring of people with DS best suited for treatment with AD therapies.
Collapse
|
48
|
Brinkmalm G, Hong W, Wang Z, Liu W, O'Malley TT, Sun X, Frosch MP, Selkoe DJ, Portelius E, Zetterberg H, Blennow K, Walsh DM. Identification of neurotoxic cross-linked amyloid-β dimers in the Alzheimer's brain. Brain 2020; 142:1441-1457. [PMID: 31032851 DOI: 10.1093/brain/awz066] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/19/2019] [Accepted: 01/27/2019] [Indexed: 11/13/2022] Open
Abstract
The primary structure of canonical amyloid-β-protein was elucidated more than 30 years ago, yet the forms of amyloid-β that play a role in Alzheimer's disease pathogenesis remain poorly defined. Studies of Alzheimer's disease brain extracts suggest that amyloid-β, which migrates on sodium dodecyl sulphate polyacrylamide gel electrophoresis with a molecular weight of ∼7 kDa (7kDa-Aβ), is particularly toxic; however, the nature of this species has been controversial. Using sophisticated mass spectrometry and sensitive assays of disease-relevant toxicity we show that brain-derived bioactive 7kDa-Aβ contains a heterogeneous mixture of covalently cross-linked dimers in the absence of any other detectable proteins. The identification of amyloid-β dimers may open a new phase of Alzheimer's research and allow a better understanding of Alzheimer's disease, and how to monitor and treat this devastating disorder. Future studies investigating the bioactivity of individual dimers cross-linked at known sites will be critical to this effort.
Collapse
|
49
|
Sanderson JB, De S, Jiang H, Rovere M, Jin M, Zaccagnini L, Hays Watson A, De Boni L, Lagomarsino VN, Young-Pearse TL, Liu X, Pochapsky TC, Hyman BT, Dickson DW, Klenerman D, Selkoe DJ, Bartels T. Analysis of α-synuclein species enriched from cerebral cortex of humans with sporadic dementia with Lewy bodies. Brain Commun 2020; 2:fcaa010. [PMID: 32280944 PMCID: PMC7130446 DOI: 10.1093/braincomms/fcaa010] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/23/2019] [Accepted: 01/09/2020] [Indexed: 02/06/2023] Open
Abstract
Since researchers identified α-synuclein as the principal component of Lewy bodies and Lewy neurites, studies have suggested that it plays a causative role in the pathogenesis of dementia with Lewy bodies and other ‘synucleinopathies’. While α-synuclein dyshomeostasis likely contributes to the neurodegeneration associated with the synucleinopathies, few direct biochemical analyses of α-synuclein from diseased human brain tissue currently exist. In this study, we analysed sequential protein extracts from a substantial number of patients with neuropathological diagnoses of dementia with Lewy bodies and corresponding controls, detecting a shift of cytosolic and membrane-bound physiological α-synuclein to highly aggregated forms. We then fractionated aqueous extracts (cytosol) from cerebral cortex using non-denaturing methods to search for soluble, disease-associated high molecular weight species potentially associated with toxicity. We applied these fractions and corresponding insoluble fractions containing Lewy-type aggregates to several reporter assays to determine their bioactivity and cytotoxicity. Ultimately, high molecular weight cytosolic fractions enhances phospholipid membrane permeability, while insoluble, Lewy-associated fractions induced morphological changes in the neurites of human stem cell-derived neurons. While the concentrations of soluble, high molecular weight α-synuclein were only slightly elevated in brains of dementia with Lewy bodies patients compared to healthy, age-matched controls, these observations suggest that a small subset of soluble α-synuclein aggregates in the brain may drive early pathogenic effects, while Lewy body-associated α-synuclein can drive neurotoxicity.
Collapse
|
50
|
Cha DJ, Mengel D, Mustapic M, Liu W, Selkoe DJ, Kapogiannis D, Galasko D, Rissman RA, Bennett DA, Walsh DM. miR-212 and miR-132 Are Downregulated in Neurally Derived Plasma Exosomes of Alzheimer's Patients. Front Neurosci 2019; 13:1208. [PMID: 31849573 PMCID: PMC6902042 DOI: 10.3389/fnins.2019.01208] [Citation(s) in RCA: 117] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/25/2019] [Indexed: 12/14/2022] Open
Abstract
It was recently discovered that brain cells release extracellular vesicles (EV) which can pass from brain into blood. These findings raise the possibility that brain-derived EV’s present in blood can be used to monitor disease processes occurring in the cerebrum. Since the levels of certain micro-RNAs (miRNAs) have been reported to be altered in Alzheimer’s disease (AD) brain, we sought to assess miRNA dysregulation in AD brain tissue and to determine if these changes were reflected in neural EVs isolated from blood of subjects with AD. To this end, we employed high-content miRNA arrays to search for differences in miRNAs in RNA pools from brain tissue of AD (n = 5), high pathological control (HPC) (n = 5), or cognitively intact pathology-free controls (n = 5). Twelve miRNAs were altered by >1.5-fold in AD compared to controls, and six of these were also changed compared to HPCs. Analysis of hits in brain extracts from 11 AD, 7 HPCs and 9 controls revealed a similar fold difference in these six miRNAs, with three showing statistically significant group differences and one with a strong trend toward group differences. Thereafter, we focused on the four miRNAs that showed group differences and measured their content in neurally derived blood EVs isolated from 63 subjects: 16 patients with early stage dementia and a CSF Aβ42+ tau profile consistent with AD, 16 individuals with mild cognitive impairment (MCI) and an AD CSF profile, and 31 cognitively intact controls with normal CSF Aβ42+ tau levels. ROC analysis indicated that measurement of miR-132-3p in neurally-derived plasma EVs showed good sensitivity and specificity to diagnose AD, but did not effectively separate individuals with AD-MCI from controls. Moreover, when we measured the levels of a related miRNA, miR-212, we found that this miRNA was also decreased in neural EVs from AD patients compared to controls. Our results suggest that measurement of miR-132 and miR-212 in neural EVs should be further investigated as a diagnostic aid for AD and as a potential theragnostic.
Collapse
|