1
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Long DM, Cravetchi O, Chow ES, Allen C, Kretzschmar D. The amyloid precursor protein intracellular domain induces sleep disruptions and its nuclear localization fluctuates in circadian pacemaker neurons in Drosophila and mice. Neurobiol Dis 2024; 192:106429. [PMID: 38309627 DOI: 10.1016/j.nbd.2024.106429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 11/17/2023] [Accepted: 02/01/2024] [Indexed: 02/05/2024] Open
Abstract
The most prominent symptom of Alzheimer's disease (AD) is cognitive decline; however, sleep and other circadian disruptions are also common in AD patients. Sleep disruptions have been connected with memory problems and therefore the changes in sleep patterns observed in AD patients may also actively contribute to cognitive decline. However, the underlying molecular mechanisms that connect sleep disruptions and AD are unclear. A characteristic feature of AD is the formation of plaques consisting of Amyloid-β (Aβ) peptides generated by cleavage of the Amyloid Precursor Protein (APP). Besides Aβ, APP cleavage generates several other fragments, including the APP intracellular domain (AICD) that has been linked to transcriptional regulation and neuronal homeostasis. Here we show that overexpression of the AICD reduces the early evening expression of two core clock genes and disrupts the sleep pattern in flies. Analyzing the subcellular localization of the AICD in pacemaker neurons, we found that the AICD levels in the nucleus are low during daytime but increase at night. While this pattern of nuclear AICD persisted with age, the nighttime levels were higher in aged flies. Increasing the cleavage of the fly APP protein also disrupted AICD nuclear localization. Lastly, we show that the day/nighttime nuclear pattern of the AICD is also detectable in neurons in the suprachiasmatic nucleus of mice and that it also changes with age. Together, these data suggest that AD-associated changes in APP processing and the subsequent changes in AICD levels may cause sleep disruptions in AD.
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Affiliation(s)
- Dani M Long
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR 97239, USA.
| | - Olga Cravetchi
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR 97239, USA
| | - Eileen S Chow
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA
| | - Charles Allen
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR 97239, USA
| | - Doris Kretzschmar
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR 97239, USA
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2
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Yao Y, Kang SS, Xia Y, Wang ZH, Liu X, Muller T, Sun YE, Ye K. A delta-secretase-truncated APP fragment activates CEBPB, mediating Alzheimer's disease pathologies. Brain 2021; 144:1833-1852. [PMID: 33880508 DOI: 10.1093/brain/awab062] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 12/10/2020] [Accepted: 12/10/2020] [Indexed: 11/13/2022] Open
Abstract
Amyloid-β precursor protein (APP) is sequentially cleaved by secretases and generates amyloid-β, the major components in senile plaques in Alzheimer's disease. APP is upregulated in human Alzheimer's disease brains. However, the molecular mechanism of how APP contributes to Alzheimer's disease pathogenesis remains incompletely understood. Here we show that truncated APP C586-695 fragment generated by δ-secretase directly binds to CCAAT/enhancer-binding protein beta (CEBPB), an inflammatory transcription factor, and enhances its transcriptional activity, escalating Alzheimer's disease-related gene expression and pathogenesis. The APP C586-695 fragment, but not full-length APP, strongly associates with CEBPB and elicits its nuclear translocation and augments the transcriptional activities on APP itself, MAPT (microtubule-associated protein tau), δ-secretase and inflammatory cytokine mRNA expression, finally triggering Alzheimer's disease pathology and cognitive disorder in a viral overexpression mouse model. Blockade of δ-secretase cleavage of APP by mutating the cleavage sites reduces its stimulatory effect on CEBPB, alleviating amyloid pathology and cognitive dysfunctions. Clearance of APP C586-695 from 5xFAD mice by antibody administration mitigates Alzheimer's disease pathologies and restores cognitive functions. Thus, in addition to the sequestration of amyloid-β, APP implicates in Alzheimer's disease pathology by activating CEBPB upon δ-secretase cleavage.
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Affiliation(s)
- Yinan Yao
- Tongji Hospital, Tongji University School of Medicine, Shanghai 20065, P.R. China.,Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Seong Su Kang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Yiyuan Xia
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Zhi-Hao Wang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Xia Liu
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Thorsten Muller
- Department of Molecular Biochemistry, Cell Signalling, Ruhr-University Bochum, 44801 Bochum, Germany.,Institute of Psychiatric Phenomics and Genomics (IPPG), University Hospital, LMU Munich, Munich 80336, Germany
| | - Yi E Sun
- Tongji Hospital, Tongji University School of Medicine, Shanghai 20065, P.R. China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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3
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Capone R, Tiwari A, Hadziselimovic A, Peskova Y, Hutchison JM, Sanders CR, Kenworthy AK. The C99 domain of the amyloid precursor protein resides in the disordered membrane phase. J Biol Chem 2021; 296:100652. [PMID: 33839158 PMCID: PMC8113881 DOI: 10.1016/j.jbc.2021.100652] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 12/11/2022] Open
Abstract
Processing of the amyloid precursor protein (APP) via the amyloidogenic pathway is associated with the etiology of Alzheimer's disease. The cleavage of APP by β-secretase to generate the transmembrane 99-residue C-terminal fragment (C99) and subsequent processing of C99 by γ-secretase to yield amyloid-β (Aβ) peptides are essential steps in this pathway. Biochemical evidence suggests that amyloidogenic processing of C99 occurs in cholesterol- and sphingolipid-enriched liquid-ordered phase membrane rafts. However, direct evidence that C99 preferentially associates with these rafts has remained elusive. Here, we tested this by quantifying the affinity of C99-GFP for raft domains in cell-derived giant plasma membrane vesicles (GPMVs). We found that C99 was essentially excluded from ordered domains in vesicles from HeLa cells, undifferentiated SH-SY5Y cells, or SH-SY5Y-derived neurons; instead, ∼90% of C99 partitioned into disordered domains. The strong association of C99 with disordered domains occurred independently of its cholesterol-binding activity or homodimerization, or of the presence of the familial Alzheimer disease Arctic mutation (APP E693G). Finally, through biochemical studies we confirmed previous results, which showed that C99 is processed in the plasma membrane by α-secretase, in addition to the well-known γ-secretase. These findings suggest that C99 itself lacks an intrinsic affinity for raft domains, implying that either i) amyloidogenic processing of the protein occurs in disordered regions of the membrane, ii) processing involves a marginal subpopulation of C99 found in rafts, or iii) as-yet-unidentified protein-protein interactions with C99 in living cells drive this protein into membrane rafts to promote its cleavage therein.
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Affiliation(s)
- Ricardo Capone
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Ajit Tiwari
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Yelena Peskova
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
| | - James M Hutchison
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Anne K Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA.
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4
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Probst S, Riese F, Kägi L, Krüger M, Russi N, Nitsch RM, Konietzko U. Lysine acetyltransferase Tip60 acetylates the APP adaptor Fe65 to increase its transcriptional activity. Biol Chem 2021; 402:481-499. [PMID: 33938178 DOI: 10.1515/hsz-2020-0279] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/18/2020] [Indexed: 11/15/2022]
Abstract
Proteolytic processing of the amyloid precursor protein (APP) releases the APP intracellular domain (AICD) from the membrane. Bound to the APP adaptor protein Fe65 and the lysine acetyltransferase (KAT) Tip60, AICD translocates to the nucleus. Here, the complex forms spherical condensates at sites of endogenous target genes, termed AFT spots (AICD-Fe65-Tip60). We show that loss of Tip60 KAT activity prevents autoacetylation, reduces binding of Fe65 and abolishes Fe65-mediated stabilization of Tip60. Autoacetylation is a prerequisite for AFT spot formation, with KAT-deficient Tip60 retained together with Fe65 in speckles. We identify lysine residues 204 and 701 of Fe65 as acetylation targets of Tip60. We do not detect acetylation of AICD. Mutation of Fe65 K204 and K701 to glutamine, mimicking acetylation-induced charge neutralization, increases the transcriptional activity of Fe65 whereas Tip60 inhibition reduces it. The lysine deacetylase (KDAC) class III Sirt1 deacetylates Fe65 and pharmacological modulation of Sirt1 activity regulates Fe65 transcriptional activity. A second acetylation/deacetylation cycle, conducted by CBP and class I/II KDACs at different lysine residues, regulates stability of Fe65. This is the first report describing a role for acetylation in the regulation of Fe65 transcriptional activity, with Tip60 being the only KAT tested that supports AFT spot formation.
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Affiliation(s)
- Sabine Probst
- Institute for Regenerative Medicine (IREM), University of Zurich Campus Schlieren, Wagistrasse 12, CH-8952 Schlieren, Switzerland
| | - Florian Riese
- Institute for Regenerative Medicine (IREM), University of Zurich Campus Schlieren, Wagistrasse 12, CH-8952 Schlieren, Switzerland
| | - Larissa Kägi
- Institute for Regenerative Medicine (IREM), University of Zurich Campus Schlieren, Wagistrasse 12, CH-8952 Schlieren, Switzerland
| | - Maik Krüger
- Institute for Regenerative Medicine (IREM), University of Zurich Campus Schlieren, Wagistrasse 12, CH-8952 Schlieren, Switzerland
| | - Natalie Russi
- Institute for Regenerative Medicine (IREM), University of Zurich Campus Schlieren, Wagistrasse 12, CH-8952 Schlieren, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine (IREM), University of Zurich Campus Schlieren, Wagistrasse 12, CH-8952 Schlieren, Switzerland
| | - Uwe Konietzko
- Institute for Regenerative Medicine (IREM), University of Zurich Campus Schlieren, Wagistrasse 12, CH-8952 Schlieren, Switzerland
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5
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FoxA2 and RNA Pol II mediate human islet amyloid polypeptide turnover in ER-stressed pancreatic β-cells. Biochem J 2021; 478:1261-1282. [PMID: 33650632 DOI: 10.1042/bcj20200984] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 12/25/2022]
Abstract
Here, we investigated transcriptional and trafficking mechanisms of human islet amyloid polypeptide (hIAPP) in normal and stressed β-cells. In high glucose-challenged human islets and rat insulinoma cells overexpressing hIAPP, cell fractionation studies revealed increased accumulation of hIAPP. Unexpectedly, a significant fraction (up to 22%) of hIAPP was found in the nuclear soluble and chromatin-enriched fractions of cultured human islet and rat insulinoma cells. The nucleolar accumulation of monomeric forms of hIAPP did not have any adverse effect on the proliferation of β-cells nor did it affect nucleolar organization or function. However, intact nucleolar organization and function were essential for hIAPP expression under normal and ER-stress conditions as RNA polymerase II inhibitor, α-amanitin, reduced hIAPP protein expression evoked by high glucose and thapsigargin. Promoter activity studies revealed the essential role of transcription factor FoxA2 in hIAPP promoter activation in ER-stressed β-cells. Transcriptome and secretory studies demonstrate that the biosynthetic and secretory capacity of islet β-cells was preserved during ER stress. Thus, the main reason for increased intracellular hIAPP accumulation is its enhanced biosynthesis under these adverse conditions.
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6
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Probst S, Krüger M, Kägi L, Thöni S, Schuppli D, Nitsch RM, Konietzko U. Fe65 is the sole member of its family that mediates transcription regulated by the amyloid precursor protein. J Cell Sci 2020; 133:jcs242917. [PMID: 32843577 DOI: 10.1242/jcs.242917] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 07/11/2020] [Indexed: 08/31/2023] Open
Abstract
The amyloid precursor protein (APP), a central molecule in Alzheimer's disease (AD), has physiological roles in cell adhesion and signaling, migration, neurite outgrowth and synaptogenesis. Intracellular adapter proteins mediate the function of transmembrane proteins. Fe65 (also known as APBB1) is a major APP-binding protein. Regulated intramembrane proteolysis (RIP) by γ-secretase releases the APP intracellular domain (AICD), together with the interacting proteins, from the membrane. We studied the impact of the Fe65 family (Fe65, and its homologs Fe65L1 and Fe65L2, also known as APBB2 and APBB3, respectively) on the nuclear signaling function of the AICD. All Fe65 family members increased amyloidogenic processing of APP, generating higher levels of β-cleaved APP stubs and AICD. However, Fe65 was the only family member supporting AICD translocation to nuclear spots and its transcriptional activity. Using a recently established transcription assay, we dissected the transcriptional activity of Fe65 and provide strong evidence that Fe65 represents a transcription factor. We show that Fe65 relies on the lysine acetyltransferase Tip60 (also known as KAT5) for nuclear translocation. Furthermore, inhibition of APP cleavage reduces nuclear Tip60 levels, but this does not occur in Fe65-knockout cells. The rate of APP cleavage therefore regulates the nuclear translocation of AICD-Fe65-Tip60 (AFT) complexes, to promote transcription by Fe65.
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Affiliation(s)
- Sabine Probst
- Institute for Regenerative Medicine - IREM, University of Zurich, Campus Schlieren, Wagistrasse 12, 8952 Schlieren - Zurich, Switzerland
| | - Maik Krüger
- Institute for Regenerative Medicine - IREM, University of Zurich, Campus Schlieren, Wagistrasse 12, 8952 Schlieren - Zurich, Switzerland
| | - Larissa Kägi
- Institute for Regenerative Medicine - IREM, University of Zurich, Campus Schlieren, Wagistrasse 12, 8952 Schlieren - Zurich, Switzerland
| | - Sarina Thöni
- Institute for Regenerative Medicine - IREM, University of Zurich, Campus Schlieren, Wagistrasse 12, 8952 Schlieren - Zurich, Switzerland
| | - Daniel Schuppli
- Institute for Regenerative Medicine - IREM, University of Zurich, Campus Schlieren, Wagistrasse 12, 8952 Schlieren - Zurich, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine - IREM, University of Zurich, Campus Schlieren, Wagistrasse 12, 8952 Schlieren - Zurich, Switzerland
| | - Uwe Konietzko
- Institute for Regenerative Medicine - IREM, University of Zurich, Campus Schlieren, Wagistrasse 12, 8952 Schlieren - Zurich, Switzerland
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7
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Hicks D, Jones A, Pickering-Brown S, Hooper N. The cellular expression and proteolytic processing of the amyloid precursor protein is independent of TDP-43. Biosci Rep 2020; 40:BSR20200435. [PMID: 32301481 PMCID: PMC7189496 DOI: 10.1042/bsr20200435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/03/2020] [Accepted: 04/06/2020] [Indexed: 02/07/2023] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative condition, of which one of the cardinal pathological hallmarks is the extracellular accumulation of amyloid β (Aβ) peptides. These peptides are generated via proteolysis of the amyloid precursor protein (APP), in a manner dependent on the β-secretase, BACE1 and the multicomponent γ-secretase complex. Recent data also suggest a contributory role in AD of transactive response DNA binding protein 43 (TDP-43). There is little insight into a possible mechanism linking TDP-43 and APP processing. To this end, we used cultured human neuronal cells to investigate the ability of TDP-43 to interact with APP and modulate its proteolytic processing. Immunocytochemistry showed TDP-43 to be spatially segregated from both the extranuclear APP holoprotein and its nuclear C-terminal fragment. The latter (APP intracellular domain) was shown to predominantly localise to nucleoli, from which TDP-43 was excluded. Furthermore, neither overexpression of each of the APP isoforms nor siRNA-mediated knockdown of APP had any effect on TDP-43 expression. Doxycycline-stimulated overexpression of TDP-43 was explored in an inducible cell line. Overexpression of TDP-43 had no effect on expression of the APP holoprotein, nor any of the key proteins involved in its proteolysis. Furthermore, increased TDP-43 expression had no effect on BACE1 enzymatic activity or immunoreactivity of Aβ1-40, Aβ1-42 or the Aβ1-40:Aβ1-42 ratio. Also, siRNA-mediated knockdown of TDP-43 had no effect on BACE1 immunoreactivity. Taken together, these data indicate that TDP-43 function and/or dysfunction in AD is likely independent from dysregulation of APP expression and proteolytic processing and Aβ generation.
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Affiliation(s)
- David A. Hicks
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | - Alys C. Jones
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | - Stuart M. Pickering-Brown
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | - Nigel M. Hooper
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
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8
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Lee YJ, Ch'ng TH. RIP at the Synapse and the Role of Intracellular Domains in Neurons. Neuromolecular Med 2019; 22:1-24. [PMID: 31346933 DOI: 10.1007/s12017-019-08556-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/12/2019] [Indexed: 12/18/2022]
Abstract
Regulated intramembrane proteolysis (RIP) occurs in a cell when transmembrane proteins are cleaved by intramembrane proteases such as secretases to generate soluble protein fragments in the extracellular environment and the cytosol. In the cytosol, these soluble intracellular domains (ICDs) have local functions near the site of cleavage or in many cases, translocate to the nucleus to modulate gene expression. While the mechanism of RIP is relatively well studied, the fate and function of ICDs for most substrate proteins remain poorly characterized. In neurons, RIP occurs in various subcellular compartments including at the synapse. In this review, we summarize current research on RIP in neurons, focusing specifically on synaptic proteins where the presence and function of the ICDs have been reported. We also briefly discuss activity-driven processing of RIP substrates at the synapse and the cellular machinery that support long-distance transport of ICDs from the synapse to the nucleus. Finally, we describe future challenges in this field of research in the context of understanding the contribution of ICDs in neuronal function.
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Affiliation(s)
- Yan Jun Lee
- Lee Kong Chian School of Medicine, Nanyang Technological University, Clinical Science Building, 11 Mandalay Road, 10-01-01 M, Singapore, 308232, Singapore.,Interdisciplinary Graduate School (IGS), Nanyang Technological University, Singapore, Singapore
| | - Toh Hean Ch'ng
- Lee Kong Chian School of Medicine, Nanyang Technological University, Clinical Science Building, 11 Mandalay Road, 10-01-01 M, Singapore, 308232, Singapore. .,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
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9
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A fluorescent protein-readout for transcriptional activity reveals regulation of APP nuclear signaling by phosphorylation sites. Biol Chem 2019; 400:1191-1203. [DOI: 10.1515/hsz-2019-0125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/14/2019] [Indexed: 11/15/2022]
Abstract
Abstract
Signaling pathways that originate at the plasma membrane, including regulated intramembrane proteolysis (RIP), enable extracellular cues to control transcription. We modified the yeast Gal4 transcription system to study the nuclear translocation of transcriptionally active complexes using the fluorescent protein citrine (Cit) as a reporter. This enabled highly sensitive quantitative analysis of transcription in situ at the single cell level. The Gal4/UAS-Cit transcription assay displayed a sigmoidal response limited by the number of integrated reporter cassettes. We validated the assay by analyzing nuclear translocation of the amyloid precursor protein (APP) intracellular domain (AICD) and confirmed the requirement of Fe65 for nuclear translocation of AICD. In addition to the strong on-off effects on transcriptional activity, the results of this assay establish that phosphorylation modifies nuclear signaling. The Y682F mutation in APP showed the strongest increase in Cit expression, underscoring its role in regulating Fe65 binding. Together, we established a highly sensitive fluorescent protein-based assay that can monitor transcriptional activity at the single cell level and demonstrate that AICD phosphorylation affects Fe65 nuclear activity. This assay also introduces a platform for future single cell-based drug screening methods for nuclear translocation.
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10
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Herber J, Njavro J, Feederle R, Schepers U, Müller UC, Bräse S, Müller SA, Lichtenthaler SF. Click Chemistry-mediated Biotinylation Reveals a Function for the Protease BACE1 in Modulating the Neuronal Surface Glycoproteome. Mol Cell Proteomics 2018; 17:1487-1501. [PMID: 29716987 DOI: 10.1074/mcp.ra118.000608] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 04/16/2018] [Indexed: 01/09/2023] Open
Abstract
The cell surface proteome is dynamic and has fundamental roles in cell signaling. Many surface membrane proteins are proteolytically released into a cell's secretome, where they can have additional functions in cell-cell-communication. Yet, it remains challenging to determine the surface proteome and to compare it to the cell secretome, under serum-containing cell culture conditions. Here, we set up and evaluated the 'surface-spanning protein enrichment with click sugars' (SUSPECS) method for cell surface membrane glycoprotein biotinylation, enrichment and label-free quantitative mass spectrometry. SUSPECS is based on click chemistry-mediated labeling of glycoproteins, is compatible with labeling of living cells and can be combined with secretome analyses in the same experiment. Immunofluorescence-based confocal microscopy demonstrated that SUSPECS selectively labeled cell surface proteins. Nearly 700 transmembrane glycoproteins were consistently identified at the surface of primary neurons. To demonstrate the utility of SUSPECS, we applied it to the protease BACE1, which is a key drug target in Alzheimer's disease. Pharmacological BACE1-inhibition selectively remodeled the neuronal surface glycoproteome, resulting in up to 7-fold increased abundance of the BACE1 substrates APP, APLP1, SEZ6, SEZ6L, CNTN2, and CHL1, whereas other substrates were not or only mildly affected. Interestingly, protein changes at the cell surface only partly correlated with changes in the secretome. Several altered proteins were validated by immunoblots in neurons and mouse brains. Apparent nonsubstrates, such as TSPAN6, were also increased, indicating that BACE1-inhibition may lead to unexpected secondary effects. In summary, SUSPECS is broadly useful for determination of the surface glycoproteome and its correlation with the secretome.
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Affiliation(s)
- Julia Herber
- From the ‡German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,§Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Jasenka Njavro
- From the ‡German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,§Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Regina Feederle
- From the ‡German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,¶Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,‖Institute for Diabetes and Obesity, Monoclonal Antibody Research Group, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Munich, Germany
| | - Ute Schepers
- **Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics (ITG), Karlsruhe, Germany
| | - Ulrike C Müller
- ‡‡Department of Functional Genomics, Institute for Pharmacy and Molecular Biotechnology, Heidelberg University Heidelberg, Germany
| | - Stefan Bräse
- **Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics (ITG), Karlsruhe, Germany
| | - Stephan A Müller
- From the ‡German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,§Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Stefan F Lichtenthaler
- From the ‡German Center for Neurodegenerative Diseases (DZNE), Munich, Germany; .,§Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.,¶Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,§§Institute for Advanced Study, Technische Universität München, Munich, Germany
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11
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Schauenburg L, Liebsch F, Eravci M, Mayer MC, Weise C, Multhaup G. APLP1 is endoproteolytically cleaved by γ-secretase without previous ectodomain shedding. Sci Rep 2018; 8:1916. [PMID: 29382944 PMCID: PMC5789831 DOI: 10.1038/s41598-018-19530-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 01/04/2018] [Indexed: 12/12/2022] Open
Abstract
Regulated intramembrane proteolysis of the amyloid precursor protein (APP) and its homologs, the APP like proteins APLP1 and APLP2, is typically a two-step process, which is initiated by ectodomain-shedding of the substrates by α- or β-secretases. Growing evidence, however, indicates that the cleavage process for APLP1 is different than for APP. Here, we describe that full-length APLP1, but not APP or APLP2, is uniquely cleaved by γ-secretase without previous ectodomain shedding. The new fragment, termed sAPLP1γ, was exclusively associated with APLP1, not APP, APLP2. We provide an exact molecular analysis showing that sAPLP1γ was uniquely generated by γ-secretase from full-length APLP1. Mass spectrometry analysis showed that the sAPLP1γ fragment and the longest Aβ-like peptide share the C-terminus. This novel mechanism of γ-secretase action is consistent with an ϵ-cut based upon the nature of the reaction in APP. We further demonstrate that the APLP1 transmembrane sequence is the critical determinant for γ-shedding and release of full-length APLP1. Moreover, the APLP1 TMS is sufficient to convert larger type-I membrane proteins like APP into direct γ-secretase substrates. Taken together, the direct cleavage of APLP1 is a novel feature of the γ-secretase prompting a re-thinking of γ-secretase activity modulation as a therapeutic strategy for Alzheimer disease.
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Affiliation(s)
- Linda Schauenburg
- Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany.,Sphingotec Therapeutics GmbH, Neuendorfstr. 15a, 16761, Hennigsdorf, Germany
| | - Filip Liebsch
- Department of Pharmacology & Therapeutics and Integrated Program in Neuroscience, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, H3G 1Y6, Canada
| | - Murat Eravci
- Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany
| | - Magnus C Mayer
- Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany.,Miltenyi Biotec GmbH, Robert-Koch-Strasse 1, 17166, Teterow, Germany
| | - Christoph Weise
- Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany
| | - Gerhard Multhaup
- Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany. .,Department of Pharmacology & Therapeutics and Integrated Program in Neuroscience, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, H3G 1Y6, Canada.
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Altered subcellular localization of fragile X mental retardation signaling partners and targets in superior frontal cortex of individuals with schizophrenia. Neuroreport 2017; 28:1066-1070. [PMID: 28902714 DOI: 10.1097/wnr.0000000000000880] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Schizophrenia is a severe, debilitating, neurodevelopmental disorder that affects 1% of the world's population. Recent findings from our laboratory have identified reduced levels of fragile X mental retardation protein (FMRP) and several downstream FMRP targets in superior frontal cortex of individuals with schizophrenia. We hypothesized that altered subcellular expression of FMRP and its signaling partners may explain these changes. In the current study we employed subcellular fractionation and western blotting to determine levels of FMRP, phosphorylated-FMRP as well as selected signaling partners [protein phosphatase 2A catalytic subunit (PP2AC), p70 S6 kinase (p70 S6K), and amyloid-β A4 precursor protein (APP)] in the total homogenate, nuclear, and rough endoplasmic reticulum fractions in superior frontal cortex of individuals with schizophrenia versus controls (N=12/group). In total homogenate of individuals with schizophrenia, we identified significantly lower levels of FMRP, phosphorylated-FMRP, and PP2AC. In the nuclear fraction of individuals with schizophrenia we found significantly higher levels of PP2AC, p70 S6K, APP 120 kDa, and APP 88 kDa proteins. Finally, in rough endoplasmic reticulum of individuals with schizophrenia, we identified significantly lower protein levels of p70 S6K and APP 120 kDa. These results provide evidence for a potential mechanism to explain altered FMRP expression in schizophrenia.
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Small things matter: Implications of APP intracellular domain AICD nuclear signaling in the progression and pathogenesis of Alzheimer’s disease. Prog Neurobiol 2017; 156:189-213. [DOI: 10.1016/j.pneurobio.2017.05.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 01/08/2023]
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APLP1 Is a Synaptic Cell Adhesion Molecule, Supporting Maintenance of Dendritic Spines and Basal Synaptic Transmission. J Neurosci 2017; 37:5345-5365. [PMID: 28450540 DOI: 10.1523/jneurosci.1875-16.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 02/22/2017] [Accepted: 03/24/2017] [Indexed: 12/19/2022] Open
Abstract
The amyloid precursor protein (APP), a key player in Alzheimer's disease, belongs to the family of synaptic adhesion molecules (SAMs) due to its impact on synapse formation and synaptic plasticity. These functions are mediated by both the secreted APP ectodomain that acts as a neurotrophic factor and full-length APP forming trans-cellular dimers. Two homologs of APP exist in mammals: the APP like proteins APLP1 and APLP2, exhibiting functions that partly overlap with those of APP. Here we tested whether APLP1 and APLP2 also show features of SAMs. We found that all three family members were upregulated during postnatal development coinciding with synaptogenesis. We observed presynaptic and postsynaptic localization of all APP family members and could show that heterologous expression of APLP1 or APLP2 in non-neuronal cells induces presynaptic differentiation in contacting axons of cocultured neurons, similar to APP and other SAMs. Moreover, APP/APLPs all bind to synaptic-signaling molecules, such as MINT/X11. Furthermore, we report that aged APLP1 knock-out mice show impaired basal transmission and a reduced mEPSC frequency, likely resulting from reduced spine density. This demonstrates an essential nonredundant function of APLP1 at the synapse. Compared to APP, APLP1 exhibits increased trans-cellular binding and elevated cell-surface levels due to reduced endocytosis. In conclusion, our results establish that APLPs show typical features of SAMs and indicate that increased surface expression, as observed for APLP1, is essential for proper synapse formation in vitro and synapse maintenance in vivoSIGNIFICANCE STATEMENT According to the amyloid-cascade hypothesis, Alzheimer's disease is caused by the accumulation of Aβ peptides derived from sequential cleavage of the amyloid precursor protein (APP) by β-site APP cleaving enzyme 1 (BACE1) and γ-secretase. Here we show that all mammalian APP family members (APP, APLP1, and APLP2) exhibit synaptogenic activity, involving trans-synaptic dimerization, similar to other synaptic cell adhesion molecules, such as Neuroligin/Neurexin. Importantly, our study revealed that the loss of APLP1, which is one of the major substrates of BACE1, causes reduced spine density in aged mice. Because some therapeutic interventions target APP processing (e.g., BACE inhibitors), those strategies may alter APP/APLP physiological function. This should be taken into account for the development of pharmaceutical treatments of Alzheimer's disease.
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Extensive nuclear sphere generation in the human Alzheimer's brain. Neurobiol Aging 2016; 48:103-113. [PMID: 27644079 DOI: 10.1016/j.neurobiolaging.2016.08.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 08/16/2016] [Accepted: 08/18/2016] [Indexed: 10/21/2022]
Abstract
Nuclear spheres are protein aggregates consisting of FE65, TIP60, BLM, and other yet unknown proteins. Generation of these structures in the cellular nucleus is putatively modulated by the amyloid precursor protein (APP), either by its cleavage or its phosphorylation. Nuclear spheres were preferentially studied in cell culture models and their existence in the human brain had not been known. Existence of nuclear spheres in the human brain was studied using immunohistochemistry. Cell culture experiments were used to study regulative mechanisms of nuclear sphere generation. The comparison of human frontal cortex brain samples from Alzheimer's disease (AD) patients to age-matched controls revealed a dramatically and highly significant enrichment of nuclear spheres in the AD brain. Costaining demonstrated that neurons are distinctly affected by nuclear spheres, but astrocytes never are. Nuclear spheres were predominantly found in neurons that were negative for threonine 668 residue in APP phosphorylation. Cell culture experiments revealed that JNK3-mediated APP phosphorylation reduces the amount of sphere-positive cells. The study suggests that nuclear spheres are a new APP-derived central hallmark of AD, which might be of crucial relevance for the molecular mechanisms in neurodegeneration.
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Fe65 Is Phosphorylated on Ser289 after UV-Induced DNA Damage. PLoS One 2016; 11:e0155056. [PMID: 27176072 PMCID: PMC4866770 DOI: 10.1371/journal.pone.0155056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 04/24/2016] [Indexed: 11/19/2022] Open
Abstract
Fe65 undergoes a phosphatase-sensitive gel mobility shift after DNA damage, consistent with protein phosphorylation. A recent study identified Ser228 as a specific site of phosphorylation, targeted by the ATM and ATR protein kinases, with phosphorylation inhibiting the Fe65-dependent transcriptional activity of the amyloid precursor protein (APP). The direct binding of Fe65 to APP not only regulates target gene expression, but also contributes to secretase-mediated processing of APP, producing cytoactive proteolytic fragments including the APP intracellular domain (AICD) and cytotoxic amyloid β (Aβ) peptides. Given that the accumulation of Aβ peptides in neural plaques is a pathological feature of Alzheimer’s disease (AD), it is essential to understand the mechanisms controlling Aβ production. This will aid in the development of potential therapeutic agents that act to limit the deleterious production of Aβ peptides. The Fe65-APP complex has transcriptional activity and the complex is regulated by multiple post-translational modifications and other protein binding partners. In the present study, we have identified Ser289 as a novel site of UV-induced phosphorylation. Interestingly, this phosphorylation was mediated by ATM, rather than ATR, and occurred independently of APP. Neither phosphorylation nor mutation of Ser289 affected the Fe65-APP interaction, though this was markedly decreased after UV treatment, with a concomitant decrease in the protein levels of APP in cells. Using mutagenesis, we demonstrated that Fe65 Ser289 phosphorylation did not affect the transcriptional activity of the Fe65-APP complex, in contrast to the previously described Ser228 site.
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17
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APP Receptor? To Be or Not To Be. Trends Pharmacol Sci 2016; 37:390-411. [PMID: 26837733 DOI: 10.1016/j.tips.2016.01.005] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/07/2016] [Accepted: 01/11/2016] [Indexed: 11/22/2022]
Abstract
Amyloid precursor protein (APP) and its metabolites play a key role in Alzheimer's disease pathogenesis. The idea that APP may function as a receptor has gained momentum based on its structural similarities to type I transmembrane receptors and the identification of putative APP ligands. We review the recent experimental evidence in support of this notion and discuss how this concept is viewed in the field. Specifically, we focus on the structural and functional characteristics of APP as a cell surface receptor, and on its interaction with adaptors and signaling proteins. We also address the importance of APP function as a receptor in Alzheimer's disease etiology and discuss how this function might be potentially important for the development of novel therapeutic approaches.
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Wang X, Ma Y, Zhao Y, Chen Y, Hu Y, Chen C, Shao Y, Xue L. APLP1 promotes dFoxO-dependent cell death in Drosophila. Apoptosis 2016; 20:778-86. [PMID: 25740230 DOI: 10.1007/s10495-015-1097-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The amyloid precursor like protein-1 (APLP1) belongs to the amyloid precursor protein family that also includes the amyloid precursor protein (APP) and the amyloid precursor like protein-2 (APLP2). Though the three proteins share similar structures and undergo the same cleavage processing by α-, β- and γ-secretases, APLP1 shows divergent subcellular localization from that of APP and APLP2, and thus, may perform distinct roles in vivo. While extensive studies have been focused on APP, which is implicated in the pathogenesis of Alzheimer's disease, the functions of APLP1 remain largely elusive. Here we report that the expression of APLP1 in Drosophila induces cell death and produces developmental defects in wing and thorax. This function of APLP1 depends on the transcription factor dFoxO, as the depletion of dFoxO abrogates APLP1-induced cell death and adult defects. Consistently, APLP1 up-regulates the transcription of dFoxO target hid and reaper-two well known pro-apoptotic genes. Thus, the present study provides the first in vivo evidence that APLP1 is able to induce cell death, and that FoxO is a crucial downstream mediator of APLP1's activity.
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Affiliation(s)
- Xingjun Wang
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China,
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Modulation of BAG3 Expression and Proteasomal Activity by sAPPα Does Not Require Membrane-Tethered Holo-APP. Mol Neurobiol 2015; 53:5985-5994. [PMID: 26526841 DOI: 10.1007/s12035-015-9501-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/19/2015] [Indexed: 10/22/2022]
Abstract
Maintenance of intracellular proteostasis is essential for neuronal function, and emerging data support the view that disturbed proteostasis plays an important role in brain aging and the pathogenesis of age-related neurodegenerative disorders such as Alzheimer's disease (AD). sAPPalpha (sAPPα), the extracellularly secreted N-terminal alpha secretase cleavage product of the amyloid precursor protein (APP), has an established function in neuroprotection. Recently, we provided evidence that membrane-bound holo-APP functionally cooperates with sAPPα to mediate neuroprotection via activation of the Akt survival signaling pathway and sAPPα directly affects proteostasis. Here, we demonstrate that in addition to its anti-apoptotic function, sAPPα has effects on neuronal proteostasis under conditions of proteasomal stress. In particular, recombinant sAPPα significantly suppressed MG132-triggered expression of the co-chaperone BAG3 and aggresome formation, and it partially rescued proteasomal activity in a dose-dependent manner in SH-SY5Y neuroblastoma cells. In analogy, sAPPα was able to inhibit MG132-induced BAG3 expression in primary hippocampal neurons. Strikingly, these sAPPα-induced changes were unaltered in APP-depleted SH-SY5Y cells and APP-deficient neurons, demonstrating that holo-APP is not required for this particular function of sAPPα. Importantly, recombinant sAPPbeta (sAPPβ) failed to modulate BAG3 expression and proteostasis in APP-proficient wild-type (wt) cells, indicating that these biological effects are highly selective for sAPPα. In conclusion, we demonstrate that modulation of proteostasis is a distinct biological function of sAPPα and does not require surface-bound holo-APP. Our data shed new light on the physiological functions of APP and the interplay between APP processing and proteostasis during brain aging.
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Multhaup G, Huber O, Buée L, Galas MC. Amyloid Precursor Protein (APP) Metabolites APP Intracellular Fragment (AICD), Aβ42, and Tau in Nuclear Roles. J Biol Chem 2015; 290:23515-22. [PMID: 26296890 DOI: 10.1074/jbc.r115.677211] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Amyloid precursor protein (APP) metabolites (amyloid-β (Aβ) peptides) and Tau are the main components of senile plaques and neurofibrillary tangles, the two histopathological hallmarks of Alzheimer disease. Consequently, intense research has focused upon deciphering their physiological roles to understand their altered state in Alzheimer disease pathophysiology. Recently, the impact of APP metabolites (APP intracellular fragment (AICD) and Aβ) and Tau on the nucleus has emerged as an important, new topic. Here we discuss (i) how AICD, Aβ, and Tau reach the nucleus and how AICD and Aβ control protein expression at the transcriptional level, (ii) post-translational modifications of AICD, Aβ, and Tau, and (iii) what these three molecules have in common.
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Affiliation(s)
- Gerhard Multhaup
- From the Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada,
| | - Otmar Huber
- the Institute of Biochemistry II, Jena University Hospital, Friedrich Schiller University, D-07743 Jena, Germany, and
| | - Luc Buée
- the Jean Pierre Aubert Research Centre, Alzheimer & Tauopathies, INSERM, CHU-Lille, UMR-S 1172, University of Lille, F-59000 Lille, France
| | - Marie-Christine Galas
- the Jean Pierre Aubert Research Centre, Alzheimer & Tauopathies, INSERM, CHU-Lille, UMR-S 1172, University of Lille, F-59000 Lille, France
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Unno K, Konishi T, Nakagawa A, Narita Y, Takabayashi F, Okamura H, Hara A, Yamamoto H, Iguchi K, Hoshino M, Yasui K, Katayanagi Y, Fukutomi R, Imai S. Cognitive dysfunction and amyloid β accumulation are ameliorated by the ingestion of green soybean extract in aged mice. J Funct Foods 2015. [DOI: 10.1016/j.jff.2015.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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22
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APP intracellular domain acts as a transcriptional regulator of miR-663 suppressing neuronal differentiation. Cell Death Dis 2015; 6:e1651. [PMID: 25695604 PMCID: PMC4669786 DOI: 10.1038/cddis.2015.10] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 12/29/2014] [Indexed: 12/21/2022]
Abstract
Amyloid precursor protein (APP) is best known for its involvement in the pathogenesis of Alzheimer's disease. We have previously demonstrated that APP intracellular domain (AICD) regulates neurogenesis; however, the mechanisms underlying AICD-mediated regulation of neuronal differentiation are not yet fully characterized. Using genome-wide chromatin immunoprecipitation approaches, we found that AICD is specifically recruited to the regulatory regions of several microRNA genes, and acts as a transcriptional regulator for miR-663, miR-3648 and miR-3687 in human neural stem cells. Functional assays show that AICD negatively modulates neuronal differentiation through miR-663, a primate-specific microRNA. Microarray data further demonstrate that miR-663 suppresses the expression of multiple genes implicated in neurogenesis, including FBXL18 and CDK6. Our results indicate that AICD has a novel role in suppression of neuronal differentiation via transcriptional regulation of miR-663 in human neural stem cells.
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Zhang X, Hoey R, Koide A, Dolios G, Paduch M, Nguyen P, Wu X, Li Y, Wagner SL, Wang R, Koide S, Sisodia SS. A synthetic antibody fragment targeting nicastrin affects assembly and trafficking of γ-secretase. J Biol Chem 2014; 289:34851-61. [PMID: 25352592 DOI: 10.1074/jbc.m114.609636] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The γ-secretase complex, composed of presenilin, nicastrin (NCT), anterior pharynx-defective 1 (APH-1), and presenilin enhancer 2 (PEN-2), is assembled in a highly regulated manner and catalyzes the intramembranous proteolysis of many type I membrane proteins, including Notch and amyloid precursor protein. The Notch family of receptors plays important roles in cell fate specification during development and in adult tissues, and aberrant hyperactive Notch signaling causes some forms of cancer. γ-Secretase-mediated processing of Notch at the cell surface results in the generation of the Notch intracellular domain, which associates with several transcriptional coactivators involved in nuclear signaling events. On the other hand, γ-secretase-mediated processing of amyloid precursor protein leads to the production of amyloid β (Aβ) peptides that play an important role in the pathogenesis of Alzheimer disease. We used a phage display approach to identify synthetic antibodies that specifically target NCT and expressed them in the single-chain variable fragment (scFv) format in mammalian cells. We show that expression of a NCT-specific scFv clone, G9, in HEK293 cells decreased the production of the Notch intracellular domain but not the production of amyloid β peptides that occurs in endosomal and recycling compartments. Biochemical studies revealed that scFvG9 impairs the maturation of NCT by associating with immature forms of NCT and, consequently, prevents its association with the other components of the γ-secretase complex, leading to degradation of these molecules. The reduced cell surface levels of mature γ-secretase complexes, in turn, compromise the intramembranous processing of Notch.
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Affiliation(s)
| | - Robert Hoey
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Akiko Koide
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Georgia Dolios
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Marcin Paduch
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Phuong Nguyen
- the Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, California 92093, and
| | - Xianzhong Wu
- Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Yueming Li
- Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Steven L Wagner
- the Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, California 92093, and
| | - Rong Wang
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Shohei Koide
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
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Maarouf CL, Kokjohn TA, Walker DG, Whiteside CM, Kalback WM, Whetzel A, Sue LI, Serrano G, Jacobson SA, Sabbagh MN, Reiman EM, Beach TG, Roher AE. Biochemical assessment of precuneus and posterior cingulate gyrus in the context of brain aging and Alzheimer's disease. PLoS One 2014; 9:e105784. [PMID: 25166759 PMCID: PMC4148328 DOI: 10.1371/journal.pone.0105784] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/24/2014] [Indexed: 12/12/2022] Open
Abstract
Defining the biochemical alterations that occur in the brain during “normal” aging is an important part of understanding the pathophysiology of neurodegenerative diseases and of distinguishing pathological conditions from aging-associated changes. Three groups were selected based on age and on having no evidence of neurological or significant neurodegenerative disease: 1) young adult individuals, average age 26 years (n = 9); 2) middle-aged subjects, average age 59 years (n = 5); 3) oldest-old individuals, average age 93 years (n = 6). Using ELISA and Western blotting methods, we quantified and compared the levels of several key molecules associated with neurodegenerative disease in the precuneus and posterior cingulate gyrus, two brain regions known to exhibit early imaging alterations during the course of Alzheimer’s disease. Our experiments revealed that the bioindicators of emerging brain pathology remained steady or decreased with advancing age. One exception was S100B, which significantly increased with age. Along the process of aging, neurofibrillary tangle deposition increased, even in the absence of amyloid deposition, suggesting the presence of amyloid plaques is not obligatory for their development and that limited tangle density is a part of normal aging. Our study complements a previous assessment of neuropathology in oldest-old subjects, and within the limitations of the small number of individuals involved in the present investigation, it adds valuable information to the molecular and structural heterogeneity observed along the course of aging and dementia. This work underscores the need to examine through direct observation how the processes of amyloid deposition unfold or change prior to the earliest phases of dementia emergence.
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Affiliation(s)
- Chera L. Maarouf
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Tyler A. Kokjohn
- Department of Microbiology, Midwestern University, Glendale, Arizona, United States of America
| | - Douglas G. Walker
- Laboratory of Neuroinflammation, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Charisse M. Whiteside
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Walter M. Kalback
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Alexis Whetzel
- Laboratory of Neuroinflammation, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Lucia I. Sue
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Geidy Serrano
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Sandra A. Jacobson
- Cleo Roberts Center for Clinical Research, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Marwan N. Sabbagh
- Cleo Roberts Center for Clinical Research, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Eric M. Reiman
- Banner Alzheimer’s Institute, Phoenix, Arizona, United States of America
| | - Thomas G. Beach
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Alex E. Roher
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
- * E-mail:
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Barucker C, Harmeier A, Weiske J, Fauler B, Albring KF, Prokop S, Hildebrand P, Lurz R, Heppner FL, Huber O, Multhaup G. Nuclear translocation uncovers the amyloid peptide Aβ42 as a regulator of gene transcription. J Biol Chem 2014; 289:20182-91. [PMID: 24878959 DOI: 10.1074/jbc.m114.564690] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Although soluble species of the amyloid-β peptide Aβ42 correlate with disease symptoms in Alzheimer disease, little is known about the biological activities of amyloid-β (Aβ). Here, we show that Aβ peptides varying in lengths from 38 to 43 amino acids are internalized by cultured neuroblastoma cells and can be found in the nucleus. By three independent methods, we demonstrate direct detection of nuclear Aβ42 as follows: (i) biochemical analysis of nuclear fractions; (ii) detection of biotin-labeled Aβ in living cells by confocal laser scanning microscopy; and (iii) transmission electron microscopy of Aβ in cultured cells, as well as brain tissue of wild-type and transgenic APPPS1 mice (overexpression of amyloid precursor protein and presenilin 1 with Swedish and L166P mutations, respectively). Also, this study details a novel role for Aβ42 in nuclear signaling, distinct from the amyloid precursor protein intracellular domain. Chromatin immunoprecipitation showed that Aβ42 specifically interacts as a repressor of gene transcription with LRP1 and KAI1 promoters. By quantitative RT-PCR, we confirmed that mRNA levels of the examined candidate genes were exclusively decreased by the potentially neurotoxic Aβ42 wild-type peptide. Shorter peptides (Aβ38 or Aβ40) and other longer peptides (nontoxic Aβ42 G33A substitution or Aβ43) did not affect mRNA levels. Overall, our data indicate that the nuclear translocation of Aβ42 impacts gene regulation, and deleterious effects of Aβ42 in Alzheimer disease pathogenesis may be influenced by altering the expression profiles of disease-modifying genes.
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Affiliation(s)
- Christian Barucker
- From the Institut fuer Chemie und Biochemie, Freie Universitaet Berlin, 14195 Berlin, Germany, the Department of Pharmacology and Therapeutics, Faculty of Medicine, McGill University, Montreal, Quebec H3G 0B1, Canada
| | - Anja Harmeier
- From the Institut fuer Chemie und Biochemie, Freie Universitaet Berlin, 14195 Berlin, Germany
| | - Joerg Weiske
- the Institute of Clinical Chemistry and Pathobiochemistry, Charite-Campus Benjamin Franklin, 12203 Berlin, Germany
| | - Beatrix Fauler
- the Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Kai Frederik Albring
- the Institute of Clinical Chemistry and Pathobiochemistry, Charite-Campus Benjamin Franklin, 12203 Berlin, Germany, the Institute of Biochemistry II, Jena University Hospital, Friedrich Schiller University, 07743 Jena, Germany, and
| | | | - Peter Hildebrand
- Institute of Medical Physics and Biophysics, Charite-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Rudi Lurz
- the Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | | | - Otmar Huber
- the Institute of Clinical Chemistry and Pathobiochemistry, Charite-Campus Benjamin Franklin, 12203 Berlin, Germany, the Institute of Biochemistry II, Jena University Hospital, Friedrich Schiller University, 07743 Jena, Germany, and
| | - Gerhard Multhaup
- From the Institut fuer Chemie und Biochemie, Freie Universitaet Berlin, 14195 Berlin, Germany, the Department of Pharmacology and Therapeutics, Faculty of Medicine, McGill University, Montreal, Quebec H3G 0B1, Canada,
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26
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Grimm MOW, Mett J, Stahlmann CP, Haupenthal VJ, Zimmer VC, Hartmann T. Neprilysin and Aβ Clearance: Impact of the APP Intracellular Domain in NEP Regulation and Implications in Alzheimer's Disease. Front Aging Neurosci 2013; 5:98. [PMID: 24391587 PMCID: PMC3870290 DOI: 10.3389/fnagi.2013.00098] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/09/2013] [Indexed: 12/18/2022] Open
Abstract
One of the characteristic hallmarks of Alzheimer's disease (AD) is an accumulation of amyloid β (Aβ) leading to plaque formation and toxic oligomeric Aβ complexes. Besides the de novo synthesis of Aβ caused by amyloidogenic processing of the amyloid precursor protein (APP), Aβ levels are also highly dependent on Aβ degradation. Several enzymes are described to cleave Aβ. In this review we focus on one of the most prominent Aβ degrading enzymes, the zinc-metalloprotease Neprilysin (NEP). In the first part of the review we discuss beside the general role of NEP in Aβ degradation the alterations of the enzyme observed during normal aging and the progression of AD. In vivo and cell culture experiments reveal that a decreased NEP level results in an increased Aβ level and vice versa. In a pathological situation like AD, it has been reported that NEP levels and activity are decreased and it has been suggested that certain polymorphisms in the NEP gene result in an increased risk for AD. Conversely, increasing NEP activity in AD mouse models revealed an improvement in some behavioral tests. Therefore it has been suggested that increasing NEP might be an interesting potential target to treat or to be protective for AD making it indispensable to understand the regulation of NEP. Interestingly, it is discussed that the APP intracellular domain (AICD), one of the cleavage products of APP processing, which has high similarities to Notch receptor processing, might be involved in the transcriptional regulation of NEP. However, the mechanisms of NEP regulation by AICD, which might be helpful to develop new therapeutic strategies, are up to now controversially discussed and summarized in the second part of this review. In addition, we review the impact of AICD not only in the transcriptional regulation of NEP but also of further genes.
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Affiliation(s)
- Marcus O W Grimm
- Experimental Neurology, Saarland University , Homburg, Saar , Germany ; Neurodegeneration and Neurobiology, Saarland University , Homburg, Saar , Germany ; Deutsches Institut für DemenzPrävention, Saarland University , Homburg, Saar , Germany
| | - Janine Mett
- Experimental Neurology, Saarland University , Homburg, Saar , Germany
| | | | | | - Valerie C Zimmer
- Experimental Neurology, Saarland University , Homburg, Saar , Germany
| | - Tobias Hartmann
- Experimental Neurology, Saarland University , Homburg, Saar , Germany ; Neurodegeneration and Neurobiology, Saarland University , Homburg, Saar , Germany ; Deutsches Institut für DemenzPrävention, Saarland University , Homburg, Saar , Germany
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Maarouf CL, Kokjohn TA, Whiteside CM, Macias MP, Kalback WM, Sabbagh MN, Beach TG, Vassar R, Roher AE. Molecular Differences and Similarities Between Alzheimer's Disease and the 5XFAD Transgenic Mouse Model of Amyloidosis. BIOCHEMISTRY INSIGHTS 2013; 6:1-10. [PMID: 25210460 PMCID: PMC4154482 DOI: 10.4137/bci.s13025] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transgenic (Tg) mouse models of Alzheimer’s disease (AD) have been extensively used to study the pathophysiology of this dementia and to test the efficacy of drugs to treat AD. The 5XFAD Tg mouse, which contains two presenilin-1 and three amyloid precursor protein (APP) mutations, was designed to rapidly recapitulate a portion of the pathologic alterations present in human AD. APP and its proteolytic peptides, as well as apolipoprotein E and endogenous mouse tau, were investigated in the 5XFAD mice at 3 months, 6 months, and 9 months. AD and nondemented subjects were used as a frame of reference. APP, amyloid-beta (Aβ) peptides, APP C-terminal fragments (CT99, CT83, AICD), β-site APP-cleaving enzyme, and APLP1 substantially increased with age in the brains of 5XFAD mice. Endogenous mouse tau did not show age-related differences. The rapid synthesis of Aβ and its impact on neuronal loss and neuroinflammation make the 5XFAD mice a desirable paradigm to model AD.
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Affiliation(s)
- Chera L Maarouf
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute Sun City, AZ, USA
| | - Tyler A Kokjohn
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute Sun City, AZ, USA. ; Department of Microbiology, Midwestern University School of Medicine, Glendale, AZ, USA
| | - Charisse M Whiteside
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute Sun City, AZ, USA
| | - MiMi P Macias
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute Sun City, AZ, USA
| | - Walter M Kalback
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute Sun City, AZ, USA
| | - Marwan N Sabbagh
- Roberts Clinical Center, Banner Sun Health Research Institute Sun City, AZ, USA. ; University of Arizona College of Medicine, Phoenix, AZ, USA
| | - Thomas G Beach
- Harold Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, AZ, USA
| | - Robert Vassar
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Alex E Roher
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute Sun City, AZ, USA
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Visualization and quantification of APP intracellular domain-mediated nuclear signaling by bimolecular fluorescence complementation. PLoS One 2013; 8:e76094. [PMID: 24086696 PMCID: PMC3783399 DOI: 10.1371/journal.pone.0076094] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 08/21/2013] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The amyloid precursor protein (APP) intracellular domain (AICD) is released from full-length APP upon sequential cleavage by either α- or β-secretase followed by γ-secretase. Together with the adaptor protein Fe65 and the histone acetyltransferase Tip60, AICD forms nuclear multiprotein complexes (AFT complexes) that function in transcriptional regulation. OBJECTIVE To develop a medium-throughput machine-based assay for visualization and quantification of AFT complex formation in cultured cells. METHODS We used cotransfection of bimolecular fluorescence complementation (BiFC) fusion constructs of APP and Tip60 for analysis of subcellular localization by confocal microscopy and quantification by flow cytometry (FC). RESULTS Our novel BiFC-constructs show a nuclear localization of AFT complexes that is identical to conventional fluorescence-tagged constructs. Production of the BiFC signal is dependent on the adaptor protein Fe65 resulting in fluorescence complementation only after Fe65-mediated nuclear translocation of AICD and interaction with Tip60. We applied the AFT-BiFC system to show that the Swedish APP familial Alzheimer's disease mutation increases AFT complex formation, consistent with the notion that AICD mediated nuclear signaling mainly occurs following APP processing through the amyloidogenic β-secretase pathway. Next, we studied the impact of posttranslational modifications of AICD on AFT complex formation. Mutation of tyrosine 682 in the YENPTY motif of AICD to phenylalanine prevents phosphorylation resulting in increased nuclear AFT-BiFC signals. This is consistent with the negative impact of tyrosine phosphorylation on Fe65 binding to AICD. Finally, we studied the effect of oxidative stress. Our data shows that oxidative stress, at a level that also causes cell death, leads to a reduction in AFT-BiFC signals. CONCLUSION We established a new method for visualization and FC quantification of the interaction between AICD, Fe65 and Tip60 in the nucleus based on BiFC. It enables flow cytometric analysis of AICD nuclear signaling and is characterized by scalability and low background fluorescence.
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