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D'Avanzo C, Sliwinski C, Wagner SL, Tanzi RE, Kim DY, Kovacs DM. γ-Secretase modulators reduce endogenous amyloid β42 levels in human neural progenitor cells without altering neuronal differentiation. FASEB J 2015; 29:3335-41. [PMID: 25903103 DOI: 10.1096/fj.15-271015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 04/05/2015] [Indexed: 02/02/2023]
Abstract
Soluble γ-secretase modulators (SGSMs) selectively decrease toxic amyloid β (Aβ) peptides (Aβ42). However, their effect on the physiologic functions of γ-secretase has not been tested in human model systems. γ-Secretase regulates fate determination of neural progenitor cells. Thus, we studied the impact of SGSMs on the neuronal differentiation of ReNcell VM (ReN) human neural progenitor cells (hNPCs). Quantitative PCR analysis showed that treatment of neurosphere-like ReN cell aggregate cultures with γ-secretase inhibitors (GSIs), but not SGSMs, induced a 2- to 4-fold increase in the expression of the neuronal markers Tuj1 and doublecortin. GSI treatment also induced neuronal marker protein expression, as shown by Western blot analysis. In the same conditions, SGSM treatment selectively reduced endogenous Aβ42 levels by ∼80%. Mechanistically, we found that Notch target gene expressions were selectively inhibited by a GSI, not by SGSM treatment. We can assert, for the first time, that SGSMs do not affect the neuronal differentiation of hNPCs while selectively decreasing endogenous Aβ42 levels in the same conditions. Our results suggest that our hNPC differentiation system can serve as a useful model to test the impact of GSIs and SGSMs on both endogenous Aβ levels and γ-secretase physiologic functions including endogenous Notch signaling.
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Affiliation(s)
- Carla D'Avanzo
- *Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA; and Department of Neurosciences, University of California, San Diego, La Jolla, California, USA
| | - Christopher Sliwinski
- *Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA; and Department of Neurosciences, University of California, San Diego, La Jolla, California, USA
| | - Steven L Wagner
- *Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA; and Department of Neurosciences, University of California, San Diego, La Jolla, California, USA
| | - Rudolph E Tanzi
- *Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA; and Department of Neurosciences, University of California, San Diego, La Jolla, California, USA
| | - Doo Yeon Kim
- *Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA; and Department of Neurosciences, University of California, San Diego, La Jolla, California, USA
| | - Dora M Kovacs
- *Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA; and Department of Neurosciences, University of California, San Diego, La Jolla, California, USA
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Pinkaew D, Changtam C, Tocharus C, Thummayot S, Suksamrarn A, Tocharus J. Di-O-demethylcurcumin protects SK-N-SH cells against mitochondrial and endoplasmic reticulum-mediated apoptotic cell death induced by Aβ25-35. Neurochem Int 2014; 80:110-9. [PMID: 25451798 DOI: 10.1016/j.neuint.2014.10.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 10/20/2014] [Accepted: 10/21/2014] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative and progressive disorder. The hallmark of pathological AD is amyloid plaque which is the accumulation of amyloid β (Aβ) in extracellular neuronal cells and neurofibrillary tangles (NFT) in neuronal cells, which lead to neurotoxicity via reactive oxygen species (ROS) generation related apoptosis. Loss of synapses and synaptic damage are the best correlates of cognitive decline in AD. Neuronal cell death is the main cause of brain dysfunction and cognitive impairment. Aβ activates neuronal death via endoplasmic reticulum (ER) stress and mitochondria apoptosis pathway. This study investigated the underlying mechanisms and effects of di-O-demethylcurcumin in preventing Aβ-induced apoptosis. Pretreatment with di-O-demethylcurcumin for 2 h, which was followed by Aβ25-35 (10 µM) in human neuroblastoma SK-N-SH cells improved cell viability by using MTS assay and decreased neuronal cell apoptosis. Pretreatment with di-O-demethylcurcumin attenuated the number of nuclear condensations and number of apoptotic cells in Aβ25-35-induced group in a concentration-dependent manner by using transmission electron microscope (TEM) and flow cytometry, respectively. Di-O-demethylcurcumin also increased the ratio of Bcl-XL/Bax protein, and reduced intracellular ROS level, cytochrome c protein expression, cleaved caspase-9 protein expression, and cleaved caspase-3 protein expression. Additionally, di-O-demethylcurcumin treatment also reduced the expression of ER stress protein markers, including protein kinase RNA like endoplasmic reticulum kinase (PERK) phosphorylation, eukaryotic translation initiation factor 2 alpha (eIF2α) phosphorylation, inositol-requiring enzyme 1 (IRE1) phosphorylation, X-box-binding protein-1 (XBP-1), activating transcription factor (ATF6), C/EBP homologous protein (CHOP), and cleaved caspase-12 protein. CHOP and cleaved caspase-12 protein are the key mediators of apoptosis. Our data suggest that di-O-demethylcurcumin is a candidate protectant against neuronal death through its suppression of the apoptosis mediated by mitochondrial death and ER stress pathway.
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Affiliation(s)
- Decha Pinkaew
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Chatchawan Changtam
- Division of Physical Science, Faculty of Science and Technology, Huachiew Chalermprakiet University, Samutprakarn 10540, Thailand
| | - Chainarong Tocharus
- Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Sarinthorn Thummayot
- Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Apichart Suksamrarn
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ramkhamhaeng University, Bangkok 10240, Thailand
| | - Jiraporn Tocharus
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
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Khandekar N, Lie KH, Sachdev PS, Sidhu KS. Amyloid precursor proteins, neural differentiation of pluripotent stem cells and its relevance to Alzheimer's disease. Stem Cells Dev 2012; 21:997-1006. [PMID: 22122714 DOI: 10.1089/scd.2011.0564] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Alzheimer's disease (AD) is a leading cause of age-related dementia that is characterized by an extensive loss of neurons and synaptic transmission. The pathological hallmarks of AD are neurofibrillary tangles and deposition of β-amyloid (Aβ) plaques. Previous research has investigated how Aβ fragments disrupt synaptic mechanisms in the vulnerable regions of the brain. There is a tremendous potential for stem cell technology to extend upon this research, not only in terms of developing therapeutic applications, but also in modeling AD. Indeed, the advent of induced pluripotent stem cell technology has opened up exciting new avenues for generating patient and disease-specific cell lines from somatic cells that may be used to model AD. Amyloid precursor protein (APP) is a key protein in neuronal development and this article reviews the role of APP in AD. Stem cell technology offers the opportunity to make use of APP in the directed differentiation of induced pluripotent stem cells into functional neurons, a process that may help generate a model of AD and thereby facilitate an understanding of the mechanisms underlying this disease.
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Affiliation(s)
- Neeta Khandekar
- Faculty of Medicine, School of Psychiatry, University of New South Wales, Sydney, NSW, Australia.
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Muresan V, Muresan Z. Is abnormal axonal transport a cause, a contributing factor or a consequence of the neuronal pathology in Alzheimer's disease? FUTURE NEUROLOGY 2009; 4:761-773. [PMID: 20076770 DOI: 10.2217/fnl.09.54] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Axonal transport, the process by which membrane-bound organelles and soluble protein complexes are transported into and out of axons, ensures proper function of the neuron, including that of the synapse. As such, abnormalities in axonal transport could lead to neuronal pathology and disease. Similar to many neurodegenerative diseases, axonal transport is deficient in Alzheimer's disease (AD), a neurodegenerative brain disorder that affects old-age humans and is characterized by the deterioration of cognitive function and progressive memory loss. It was proposed that the synaptic pathology and neuronal degeneration that develops in AD could be caused by an abnormal axonal transport, and that the mutated proteins that cause early-onset AD, as well as the genetic variants that confer predisposition to late-onset AD might somehow impede axonal transport. This paper analyzes the data that support or contradict this hypothesis. Together, they indicate that, although abnormalities in axonal transport are part of the disease, additional studies are required to clearly establish to what extent deficient axonal transport is the cause or the effect of the neuronal pathology in AD, and to identify mechanisms that lead to its perturbation.
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Affiliation(s)
- Virgil Muresan
- University of Medicine & Dentistry of New Jersey, New Jersey Medical School, Department of Pharmacology & Physiology, 185 South Orange Avenue, MSB, I-683 Newark, NJ 07103, USA, Tel.: +1 973 972 2392, ,
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Korol’ TY, Korol’ SV, Kostyuk EP, Kostyuk PG. Disruption of Calcium Homeostasis in Alzheimer’s Disease. NEUROPHYSIOLOGY+ 2009. [DOI: 10.1007/s11062-009-9064-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Leuner K, Hauptmann S, Abdel-Kader R, Scherping I, Keil U, Strosznajder JB, Eckert A, Müller WE. Mitochondrial dysfunction: the first domino in brain aging and Alzheimer's disease? Antioxid Redox Signal 2007; 9:1659-75. [PMID: 17867931 DOI: 10.1089/ars.2007.1763] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
With the increasing average life span of humans and with decreasing cognitive function in elderly individuals, age-related cognitive disorders including dementia have become a major health problem in society. Aging-related mitochondrial dysfunction underlies many common neurodegenerative disorders diseases, including Alzheimer's disease (AD). AD is characterized by two major histopathological hallmarks, initially intracellular and with the progression of the disease extracellular accumulation of oligomeric and fibrillar beta-amyloid (Abeta) peptides and intracellular neurofibrillary tangles (NFT) composed of hyperphosphorylated tau protein. In this review, the authors focus on the latest findings in AD animal models indicating that these histopathological alterations induce deficits in the function of the complexes of the respiratory chain and therefore consecutively result in mitochondrial dysfunction. This parameter is intrinsically tied to oxidative stress. Both are early events in aging and especially in the pathogenesis of aging-related severe neurodegeneration. Ginkgo biloba extract seems to be of therapeutic benefit in the treatment of mild to moderate dementia of different etiology, although the data are quite heterogeneous. Herein, the authors suggest that mitochondrial protection and subsequent reduction of oxidative stress are important components of the neuroprotective activity of Ginkgo biloba extract.
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Affiliation(s)
- Kristina Leuner
- Department of Pharmacology, Zafes, Biocenter, University of Frankfurt, Germany.
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Patočka J, Slaninová J, Kunešová G. Neuroprotective peptides as drug candidates against Alzheimer's diasease. J Appl Biomed 2005. [DOI: 10.32725/jab.2005.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Tarassishin L, Yin YI, Bassit B, Li YM. Processing of Notch and amyloid precursor protein by gamma-secretase is spatially distinct. Proc Natl Acad Sci U S A 2004; 101:17050-5. [PMID: 15563588 PMCID: PMC535399 DOI: 10.1073/pnas.0408007101] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
gamma-Secretase activity is associated with a presenilin (PS)-containing macromolecular complex. Whether PS contains the active site of gamma-secretase has been controversial. One challenge is to find PS that is engaged in the active gamma-secretase complex at the cell surface, where some substrates appear to be processed. In this study, we developed an intact cell photolabeling technique that allows the direct visualization of active gamma-secretase at the cell surface. We demonstrated that active gamma-secretase is present in the plasma membrane. Moreover, the PS1 heterodimer is specifically photolabeled at the cell surface by a potent inhibitor that binds to only the active gamma-secretase. We also explored the cellular processing sites of gamma-secretase for amyloid precursor protein (APP) and Notch by using small molecular probes. MRL631, a gamma-secretase inhibitor that is unable to penetrate the cell membrane, significantly blocks gamma-secretase-mediated Notch cleavage but has little effect on APP processing. These results indicate that Notch is processed at the cell surface and that the majority of APP is processed by intracellular gamma-secretase. Furthermore, the fact that inhibitors first target gamma-secretase in the plasma membrane for Notch processing, and not for APP, will have important implications for drug development to treat Alzheimer's disease and cancer.
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Affiliation(s)
- Leonid Tarassishin
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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Fuwa H, Okamura Y, Morohashi Y, Tomita T, Iwatsubo T, Kan T, Fukuyama T, Natsugari H. Highly efficient synthesis of medium-sized lactams via intramolecular Staudinger–aza-Wittig reaction of ω-azido pentafluorophenyl ester: synthesis and biological evaluation of LY411575 analogues. Tetrahedron Lett 2004. [DOI: 10.1016/j.tetlet.2004.01.087] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Dewji NN, Valdez D, Singer SJ. The presenilins turned inside out: implications for their structures and functions. Proc Natl Acad Sci U S A 2004; 101:1057-62. [PMID: 14732691 PMCID: PMC327150 DOI: 10.1073/pnas.0307290101] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The presenilin (PS) proteins are polytopic integral membrane proteins that are critically involved in the development of Alzheimer's disease. The topography of the PS molecule in the endoplasmic reticulum membrane is widely accepted as exhibiting eight-hydrophobic-transmembrane (8-TM) helices. We have previously provided evidence, however, that the intact PS molecule is also present in the cell surface where it exhibits exclusively a 7-TM topography, which differs in significant structural features from the 8-TM model. This evidence, however, has been disparaged and generally rejected by researchers in Alzheimer's disease. The 7-TM model is definitively demonstrated in the present study for PS-1 at the surfaces of PS-1-transfected cells and for endogenous PS-1 at the surfaces of untransfected cells, by immunofluorescence studies using mAbs. These studies force substantial revision of current views of the structural and functional properties of the PS proteins.
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Affiliation(s)
- Nazneen N Dewji
- Departments of Medicine and Biology, University of California at San Diego, La Jolla, CA 92093, USA.
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Abstract
Alzheimer's disease afflicts every tenth human aged over 65. Despite the dramatic progress that has been made in understanding the disease, the exact cause of Alzheimer's disease is still unknown. Most gene mutations associated with Alzheimer's disease point at the same culprits: amyloid precursor protein and ultimately amyloid beta. The enigmatic proteases alpha-,beta-, and gamma-secretase are the three executioners of amyloid precursor protein processing, and disruption of their delicate balance is suspected to result in Alzheimer's disease. Significant progress has been made in the selective control of these proteases, regardless of the availability of structural information. Not even the absence of a robust cell-free assay for gamma-secretase could hamper the identification of nonpeptidic inhibitors of this enzyme for long. Within five years, four distinctly different structural moieties were developed and the first drug candidates are in clinical trials. Unfortunately, selective inhibition of amyloid beta formation remains a crucial issue because fundamental fragments of the gamma-secretase complex are important for other signaling events. This problem makes beta-secretase inhibition and alpha-secretase induction even more appealing.
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Affiliation(s)
- Boris Schmidt
- Clemens-Schöpf-Institute for Organic Chemistry and Biochemistry TU Darmstadt, Petersenstrasse 22 64287 Darmstadt, Germany.
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Affiliation(s)
- Michael S Wolfe
- Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA.
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Weihofen A, Binns K, Lemberg MK, Ashman K, Martoglio B. Identification of signal peptide peptidase, a presenilin-type aspartic protease. Science 2002; 296:2215-8. [PMID: 12077416 DOI: 10.1126/science.1070925] [Citation(s) in RCA: 424] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Signal peptide peptidase (SPP) catalyzes intramembrane proteolysis of some signal peptides after they have been cleaved from a preprotein. In humans, SPP activity is required to generate signal sequence-derived human lymphocyte antigen-E epitopes that are recognized by the immune system, and to process hepatitis C virus core protein. We have identified human SPP as a polytopic membrane protein with sequence motifs characteristic of the presenilin-type aspartic proteases. SPP and potential eukaryotic homologs may represent another family of aspartic proteases that promote intramembrane proteolysis to release biologically important peptides.
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Affiliation(s)
- Andreas Weihofen
- Institute of Biochemistry, Swiss Federal Institute of Technology (ETH), ETH-Hoenggerberg, 8093 Zürich, Switzerland
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