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Pham AQ, Dore K. Novel approaches to increase synaptic resilience as potential treatments for Alzheimer's disease. Semin Cell Dev Biol 2023; 139:84-92. [PMID: 35370089 DOI: 10.1016/j.semcdb.2022.03.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 12/31/2022]
Abstract
A significant proportion of brains with Alzheimer's disease pathology are obtained from patients that were cognitively normal, suggesting that differences within the brains of these individuals made them resilient to the disease. Here, we describe recent approaches that specifically increase synaptic resilience, as loss of synapses is considered to be the first change in the brains of Alzheimer's patients. We start by discussing studies showing benefit from increased expression of neurotrophic factors and protective genes. Methods that effectively make dendritic spines stronger, specifically by acting through actin network proteins, scaffolding proteins and inhibition of phosphatases are described next. Importantly, the therapeutic strategies presented in this review tackle Alzheimer's disease not by targeting plaques and tangles, but instead by making synapses resilient to the pathology associated with Alzheimer's disease, which has tremendous potential.
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Affiliation(s)
- Andrew Q Pham
- Department of Neurosciences, Center for Neural Circuits and Behavior, UCSD, La Jolla 92093, United States
| | - Kim Dore
- Department of Neurosciences, Center for Neural Circuits and Behavior, UCSD, La Jolla 92093, United States.
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2
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Dore K, Carrico Z, Alfonso S, Marino M, Koymans K, Kessels HW, Malinow R. PSD-95 protects synapses from β-amyloid. Cell Rep 2021; 35:109194. [PMID: 34077732 PMCID: PMC8237704 DOI: 10.1016/j.celrep.2021.109194] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 03/16/2021] [Accepted: 05/10/2021] [Indexed: 01/22/2023] Open
Abstract
Beta-amyloid (Aβ) depresses excitatory synapses by a poorly understood mechanism requiring NMDA receptor (NMDAR) function. Here, we show that increased PSD-95, a major synaptic scaffolding molecule, blocks the effects of Aβ on synapses. The protective effect persists in tissue lacking the AMPA receptor subunit GluA1, which prevents the confounding synaptic potentiation by increased PSD-95. Aβ modifies the conformation of the NMDAR C-terminal domain (CTD) and its interaction with protein phosphatase 1 (PP1), producing synaptic weakening. Higher endogenous levels or overexpression of PSD-95 block Aβ-induced effects on the NMDAR CTD conformation, its interaction with PP1, and synaptic weakening. Our results indicate that increased PSD-95 protects synapses from Aβ toxicity, suggesting that low levels of synaptic PSD-95 may be a molecular sign indicating synapse vulnerability to Aβ. Importantly, pharmacological inhibition of its depalmitoylation increases PSD-95 at synapses and rescues deficits caused by Aβ, possibly opening a therapeutic avenue against Alzheimer's disease.
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Affiliation(s)
- Kim Dore
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California, San Diego, San Diego, CA 92093, USA.
| | - Zachary Carrico
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California, San Diego, San Diego, CA 92093, USA
| | - Stephanie Alfonso
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California, San Diego, San Diego, CA 92093, USA
| | - Marc Marino
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California, San Diego, San Diego, CA 92093, USA
| | - Karin Koymans
- Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands
| | - Helmut W Kessels
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California, San Diego, San Diego, CA 92093, USA; Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands
| | - Roberto Malinow
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California, San Diego, San Diego, CA 92093, USA
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Dore K, Malinow R. Elevated PSD-95 Blocks Ion-flux Independent LTD: A Potential New Role for PSD-95 in Synaptic Plasticity. Neuroscience 2020; 456:43-49. [PMID: 32114099 DOI: 10.1016/j.neuroscience.2020.02.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 10/24/2022]
Abstract
We recently demonstrated that NMDA receptors (NMDARs) are capable of ion-flux independent signaling through conformational change in the NMDAR intracellular domain resulting in long-term depression of synaptic transmission (LTD). Here we show that PSD-95 overexpression blocks agonist induced conformational movement in the NMDAR intracellular domain as well as LTD that is NMDAR-dependent and ion-flux independent. Interestingly, previous studies indicate that overexpressed PSD-95 does not block NMDAR-dependent LTD. These data support a model where ion-flux independent LTD is predominant in young animals, which have synapses with low amounts of PSD-95, whereas only ion flux dependent LTD occurs at more mature synapses, which have more PSD-95 that would block ion-flux independent LTD. These results may reconcile different findings regarding ion-flux independent LTD.
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Affiliation(s)
- Kim Dore
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093, United States.
| | - Roberto Malinow
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093, United States
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Sapkota K, Dore K, Tang K, Irvine M, Fang G, Burnell ES, Malinow R, Jane DE, Monaghan DT. The NMDA receptor intracellular C-terminal domains reciprocally interact with allosteric modulators. Biochem Pharmacol 2018; 159:140-153. [PMID: 30503374 DOI: 10.1016/j.bcp.2018.11.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 11/28/2018] [Indexed: 11/27/2022]
Abstract
N-methyl-d-aspartate receptors (NMDARs) have multiple prominent roles in CNS function but their excessive or insufficient activity contributes to neuropathological/psychiatric disorders. Consequently, a variety of positive and negative allosteric modulators (PAMs and NAMs, respectively) have recently been developed. Although these modulators bind to extracellular domains, in the present report we find that the NMDAR's intracellular C-terminal domains (CTDs) significantly influence PAM/NAM activity. GluN2 CTD deletion robustly affected NAM and PAM activity with both enhancing and inhibiting effects that were compound-specific and NMDAR subunit-specific. In three cases, individual PAMs became NAMs at specific GluN2-truncated receptors. In contrast to GluN2, GluN1 CTD removal only reduced PAM activity of UBP684 and CIQ, and did not affect NAM activity. Consistent with these findings, agents altering phosphorylation state or intracellular calcium levels displayed receptor-specific and compound-specific effects on PAM activity. It is possible that the GluN2's M4 domain transmits intracellular modulatory signals from the CTD to the M1/M4 channel gating machinery and that this site is a point of convergence in the direct or indirect actions of several PAMs/NAMs thus rendering them sensitive to CTD status. Thus, allosteric modulators are likely to have a marked and varied sensitivity to post-translational modifications, protein-protein associations, and intracellular ions. The interaction between PAM activity and NMDAR CTDs appears reciprocal. GluN1 CTD-deletion eliminated UBP684, but not pregnenolone sulfate (PS), PAM activity. And, in the absence of agonists, UBP684, but not PS, was able to promote movement of fluorescently-tagged GluN1-CTDs. Thus, it may be possible to pharmacologically target NMDAR metabotropic activity in the absence of channel activation.
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Affiliation(s)
- Kiran Sapkota
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA
| | - Kim Dore
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093-0634, USA
| | - Kang Tang
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA
| | - Mark Irvine
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Guangyu Fang
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Erica S Burnell
- School of Chemistry, National University of Ireland Galway, Galway H91TK33, Ireland
| | - Roberto Malinow
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093-0634, USA
| | - David E Jane
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Daniel T Monaghan
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA.
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Dore K, Aow J, Malinow R. The Emergence of NMDA Receptor Metabotropic Function: Insights from Imaging. Front Synaptic Neurosci 2016; 8:20. [PMID: 27516738 PMCID: PMC4963461 DOI: 10.3389/fnsyn.2016.00020] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/06/2016] [Indexed: 01/19/2023] Open
Abstract
The NMDA receptor (R) participates in many important physiological and pathological processes. For example, its activation is required for both long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission, cellular models of learning and memory. Furthermore, it may play a role in the actions of amyloid-beta on synapses as well as in the signaling leading to cell death following stroke. Until recently, these processes were thought to be mediated by ion-flux through the receptor. Using a combination of imaging and electrophysiological approaches, ion-flux independent functions of the NMDAR were recently examined. In this review, we will discuss the role of metabotropic NMDAR function in LTD and synaptic dysfunction.
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Affiliation(s)
- Kim Dore
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego San Diego, CA, USA
| | - Jonathan Aow
- Genome Institute of Singapore Singapore, Singapore
| | - Roberto Malinow
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego San Diego, CA, USA
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Tsai LCL, Xie L, Dore K, Xie L, Del Rio JC, King CC, Martinez-Ariza G, Hulme C, Malinow R, Bourne PE, Newton AC. Zeta Inhibitory Peptide Disrupts Electrostatic Interactions That Maintain Atypical Protein Kinase C in Its Active Conformation on the Scaffold p62. J Biol Chem 2015; 290:21845-56. [PMID: 26187466 DOI: 10.1074/jbc.m115.676221] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Indexed: 11/06/2022] Open
Abstract
Atypical protein kinase C (aPKC) enzymes signal on protein scaffolds, yet how they are maintained in an active conformation on scaffolds is unclear. A myristoylated peptide based on the autoinhibitory pseudosubstrate fragment of the atypical PKCζ, zeta inhibitory peptide (ZIP), has been extensively used to inhibit aPKC activity; however, we have previously shown that ZIP does not inhibit the catalytic activity of aPKC isozymes in cells (Wu-Zhang, A. X., Schramm, C. L., Nabavi, S., Malinow, R., and Newton, A. C. (2012) J. Biol. Chem. 287, 12879-12885). Here we sought to identify a bona fide target of ZIP and, in so doing, unveiled a novel mechanism by which aPKCs are maintained in an active conformation on a protein scaffold. Specifically, we used protein-protein interaction network analysis, structural modeling, and protein-protein docking to predict that ZIP binds an acidic surface on the Phox and Bem1 (PB1) domain of p62, an interaction validated by peptide array analysis. Using a genetically encoded reporter for PKC activity fused to the p62 scaffold, we show that ZIP inhibits the activity of wild-type aPKC, but not a construct lacking the pseudosubstrate. These data support a model in which the pseudosubstrate of aPKCs is tethered to the acidic surface on p62, locking aPKC in an open, signaling-competent conformation. ZIP competes for binding to the acidic surface, resulting in displacement of the pseudosubstrate of aPKC and re-engagement in the substrate-binding cavity. This study not only identifies a cellular target for ZIP, but also unveils a novel mechanism by which scaffolded aPKC is maintained in an active conformation.
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Affiliation(s)
| | - Lei Xie
- the Department of Computer Science, Hunter College, the City University of New York, New York, New York 10065
| | | | - Li Xie
- Skaggs School of Pharmacy, and
| | | | - Charles C King
- Pediatric Diabetes Research Center, University of California San Diego, La Jolla, California 92093
| | - Guillermo Martinez-Ariza
- the Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85721, and
| | - Christopher Hulme
- the Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85721, and
| | | | - Philip E Bourne
- the Office of the Director, the National Institutes of Health, Bethesda, Maryland 20892
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Mataseje LF, Xiao J, Kost S, Ng LK, Dore K, Mulvey MR. Characterization of Canadian cefoxitin-resistant non-typhoidal Salmonella isolates, 2005-06. J Antimicrob Chemother 2009; 64:723-30. [DOI: 10.1093/jac/dkp249] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Buxton J, Fyfe M, King A, Deeks S, Dore K, Ahmed R, Khakhria R, Paccagnella A, Hockin J. Salmonella typhimurium definitive type 104 isolates in British Columbia, 1997-1998. Can Commun Dis Rep 1999; 25:129-33. [PMID: 10466255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Affiliation(s)
- J Buxton
- Field Epidemiology Training Program, LCDC, Ottawa, Ont
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Abstract
When the eye saccades to eccentric word targets, it tends to land in a position which can be described as the center of gravity of the configuration. By manipulating the relative intensity of the word-initial and -ending letters, it was shown that the 'global effect' of luminance distribution within words is strongly attenuated when the word-initial letters are informative and orthographically irregular. Results show that the orthographic structure of the word-initial letters exerts an influence on the saccadic computation that may cancel the luminance distribution effect.
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Affiliation(s)
- C Beauvillain
- Laboratoire de Psychologie Experimentale URA, Universite Rene Descartes, Paris, France. . jussieu.fr
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