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Kiyohara ACP, Torres DJ, Hagiwara A, Pak J, Rueli RHLH, Shuttleworth CWR, Bellinger FP. Selenoprotein P Regulates Synaptic Zinc and Reduces Tau Phosphorylation. Front Nutr 2021; 8:683154. [PMID: 34277682 PMCID: PMC8280497 DOI: 10.3389/fnut.2021.683154] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 05/26/2021] [Indexed: 01/11/2023] Open
Abstract
Selenoprotein P (SELENOP1) is a selenium-rich antioxidant protein involved in extracellular transport of selenium (Se). SELENOP1 also has metal binding properties. The trace element Zinc (Zn2+) is a neuromodulator that can be released from synaptic terminals in the brain, primarily from a subset of glutamatergic terminals. Both Zn2+ and Se are necessary for normal brain function. Although these ions can bind together with high affinity, the biological significance of an interaction of SELENOP1 with Zn2+ has not been investigated. We examined changes in brain Zn2+ in SELENOP1 knockout (KO) animals. Timm-Danscher and N-(6-methoxy-8-quinolyl)-p-toluenesulphonamide (TSQ) staining revealed increased levels of intracellular Zn2+ in the SELENOP1-/- hippocampus compared to wildtype (WT) mice. Mass spectrometry analysis of frozen whole brain samples demonstrated that total Zn2+ was not increased in the SELENOP1-/- mice, suggesting only local changes in Zn2+ distribution. Unexpectedly, live Zn2+ imaging of hippocampal slices with a selective extracellular fluorescent Zn2+ indicator (FluoZin-3) showed that SELENOP1-/- mice have impaired Zn2+ release in response to KCl-induced neuron depolarization. The zinc/metal storage protein metallothionein 3 (MT-3) was increased in SELENOP1-/- hippocampus relative to wildtype, possibly in response to an elevated Zn2+ content. We found that depriving cultured cells of selenium resulted in increased intracellular Zn2+, as did inhibition of selenoprotein GPX4 but not GPX1, suggesting the increased Zn2+ in SELENOP1-/- mice is due to a downregulation of antioxidant selenoproteins and subsequent release of Zn2+ from intracellular stores. Surprisingly, we found increased tau phosphorylation in the hippocampus of SELENOP1-/- mice, possibly resulting from intracellular zinc changes. Our findings reveal important roles for SELENOP1 in the maintenance of synaptic Zn2+ physiology and preventing tau hyperphosphorylation.
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Affiliation(s)
- Arlene C. P. Kiyohara
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Daniel J. Torres
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
- Pacific Biosciences Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Ayaka Hagiwara
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Jenna Pak
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Rachel H. L. H. Rueli
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | | | - Frederick P. Bellinger
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
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Rueli RHLH, Torres DJ, Dewing AST, Kiyohara AC, Barayuga SM, Bellinger MT, Uyehara-Lock JH, White LR, Moreira PI, Berry MJ, Perry G, Bellinger FP. Selenoprotein S Reduces Endoplasmic Reticulum Stress-Induced Phosphorylation of Tau: Potential Role in Selenate Mitigation of Tau Pathology. J Alzheimers Dis 2018; 55:749-762. [PMID: 27802219 DOI: 10.3233/jad-151208] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Previous studies demonstrated that selenium in the form of sodium selenate reduces neurofibrillary tangle formation in Alzheimer's disease models. Hyperphosphorylation of tau, which leads to formation of neurofibrillary tangles in Alzheimer's disease, is increased by endoplasmic reticulum (ER) stress. Selenoprotein S (SelS) is part of an ER membrane complex that removes misfolded proteins from the ER as a means to reduce ER stress. Selenate, as with other forms of selenium, will increase selenoprotein expression. We therefore proposed that increased SelS expression by selenate would contribute to the beneficial actions of selenate in Alzheimer's disease. SelS expression increased with ER stress and decreased under conditions of elevated glucose concentrations in the SH-SY5Y neuronal cell line. Reducing expression of SelS with siRNA promoted cell death in response to ER stress. Selenate increased SelS expression, which significantly correlated with decreased tau phosphorylation. Restricting SelS expression during ER stress conditions increased tau phosphorylation, and also promoted aggregation of phosphorylated tau in neurites and soma. In human postmortem brain, SelS expression coincided with neurofibrillary tangles, but not with amyloid-β plaques. These results indicate that selenate can alter phosphorylation of tau by increasing expression of SelS in Alzheimer's disease and potentially other neurodegenerative disorders.
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Affiliation(s)
- Rachel H L H Rueli
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Daniel J Torres
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Andrea S T Dewing
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Arlene C Kiyohara
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Stephanie M Barayuga
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Miyoko T Bellinger
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Jane H Uyehara-Lock
- Department of Pathology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Lon R White
- Pacific Health Research and Education Institute, Honolulu, HI, USA
| | - Paula I Moreira
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra and Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Marla J Berry
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - George Perry
- UTSA Neurosciences Institute and Department of Biology, University of Texas at San Antonio, San Antonio, TX, USA
| | - Frederick P Bellinger
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI, USA
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Rueli RHLH, Parubrub AC, Dewing AST, Hashimoto AC, Bellinger MT, Weeber EJ, Uyehara-Lock JH, White LR, Berry MJ, Bellinger FP. Increased selenoprotein P in choroid plexus and cerebrospinal fluid in Alzheimer's disease brain. J Alzheimers Dis 2015; 44:379-83. [PMID: 25298198 DOI: 10.3233/jad-141755] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Subjects with Alzheimer's disease (AD) have elevated brain levels of the selenium transporter selenoprotein P (Sepp1). We investigated if this elevation results from increased release of Sepp1 from the choroid plexus (CP). Sepp1 is significantly increased in CP from AD brains in comparison to non-AD brains. Sepp1 localizes to the trans-Golgi network within CP epithelia, where it is processed for secretion. The cerebrospinal fluid from AD subjects also contains increased levels Sepp1 in comparison to non-AD subjects. These findings suggest that AD pathology induces increased levels of Sepp1 within CP epithelia for release into the cerebrospinal fluid to ultimately increase brain selenium.
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Affiliation(s)
- Rachel H L H Rueli
- Cell and Molecular Biology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Arlene C Parubrub
- Cell and Molecular Biology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Andrea S T Dewing
- Cell and Molecular Biology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Ann C Hashimoto
- Cell and Molecular Biology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Miyoko T Bellinger
- Cell and Molecular Biology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Edwin J Weeber
- Molecular Pharmacology and Physiology, University of South Florida, Johnnie B. Byrd, Sr. Alzheimer's Center & Research Institute, Tampa, FL, USA
| | - Jane H Uyehara-Lock
- Pathology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Lon R White
- Pacific Health Research and Education Institute, Honolulu, HI, USA
| | - Marla J Berry
- Cell and Molecular Biology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Frederick P Bellinger
- Cell and Molecular Biology Department, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
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