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Jeong J, Kim OH, Shim J, Keum S, Hwang YE, Song S, Kim JW, Choi JH, Lee HJ, Rhee S. Microtubule acetylation induced by oxidative stress regulates subcellular distribution of lysosomal vesicles for amyloid-beta secretion. J Cell Physiol 2023; 238:2812-2826. [PMID: 37801327 DOI: 10.1002/jcp.31131] [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: 05/07/2023] [Revised: 09/04/2023] [Accepted: 09/19/2023] [Indexed: 10/07/2023]
Abstract
Excessive production and accumulation of amyloid-beta (Aβ) in the brain are one of the hallmarks of Alzheimer's disease (AD). Although oxidative stress is known to trigger and promote the progression of AD, the molecular relationship between oxidative stress and Aβ production is not yet fully understood. In this study, we demonstrate that microtubule acetylation induced by oxidative stress plays a critical role in Aβ production and secretion by altering the subcellular distribution of Aβ precursor protein (APP)-containing lysosomal vesicles. Under oxidative stress, both H4-APPSwe/Ind and HEK293T-APPSwe/Ind cell lines showed increased microtubule acetylation and Aβ secretion. Knockdown (KD) of alpha-tubulin N-acetyltransferase 1 (ATAT1) by using a lentiviral shRNA not only inhibited the generation of intermediate APP fragments, such as β-CTF and AICD, but also suppressed Aβ secretion. Oxidative stress promoted the dispersion of LAMP1-positive vesicles to the periphery of the cell through microtubule acetylation, leading to the formation of neutralized lysosomal vesicles (NLVs), which was inhibited by ATAT1 KD. Treatment of the cells with the dynein ATPase inhibitor EHNA or downregulation of LIS1, a regulator of dynein-mediated intracellular transport, increased the peripheral localization of NLVs and promoted Aβ secretion, whereas KD of ADP ribosylation factor like GTPase 8B showed the opposite result. ATAT1 KD in the hippocampal region of the 5×FAD AD mouse model also showed significant reductions in Aβ plaque accumulation and memory loss. Taken together, these findings suggest that oxidative stress-induced microtubule acetylation promotes the peripheral localization of lysosomal vesicles to form NLVs, thereby enhancing Aβ secretion.
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Affiliation(s)
- Jangho Jeong
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Ok-Hyeon Kim
- Department of Anatomy and Cell Biology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Jaeyeoung Shim
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Seula Keum
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Ye Eun Hwang
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Seongeun Song
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Jung-Woong Kim
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Jee-Hye Choi
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Hyun Jung Lee
- Department of Anatomy and Cell Biology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul, Republic of Korea
| | - Sangmyung Rhee
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
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2
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Roselli S, Satir TM, Camacho R, Fruhwürth S, Bergström P, Zetterberg H, Agholme L. APP-BACE1 Interaction and Intracellular Localization Regulate Aβ Production in iPSC-Derived Cortical Neurons. Cell Mol Neurobiol 2023; 43:3653-3668. [PMID: 37355492 PMCID: PMC10477112 DOI: 10.1007/s10571-023-01374-0] [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: 12/08/2022] [Accepted: 06/09/2023] [Indexed: 06/26/2023]
Abstract
Alzheimer's disease (AD) is characterized pathologically by amyloid β (Aβ)-containing plaques. Generation of Aβ from amyloid precursor protein (APP) by two enzymes, β- and γ-secretase, has therefore been in the AD research spotlight for decades. Despite this, how the physical interaction of APP with the secretases influences APP processing is not fully understood. Herein, we compared two genetically identical human iPSC-derived neuronal cell types: low Aβ-secreting neuroprogenitor cells (NPCs) and high Aβ-secreting mature neurons, as models of low versus high Aβ production. We investigated levels of substrate, enzymes and products of APP amyloidogenic processing and correlated them with the proximity of APP to β- and γ-secretase in endo-lysosomal organelles. In mature neurons, increased colocalization of full-length APP with the β-secretase BACE1 correlated with increased β-cleavage product sAPPβ. Increased flAPP/BACE1 colocalization was mainly found in early endosomes. In the same way, increased colocalization of APP-derived C-terminal fragment (CTF) with presenilin-1 (PSEN1), the catalytic subunit of γ-secretase, was seen in neurons as compared to NPCs. Furthermore, most of the interaction of APP with BACE1 in low Aβ-secreting NPCs seemed to derive from CTF, the remaining APP part after BACE1 cleavage, indicating a possible novel product-enzyme inhibition. In conclusion, our results suggest that interaction of APP and APP cleavage products with their secretases can regulate Aβ production both positively and negatively. β- and γ-Secretases are difficult targets for AD treatment due to their ubiquitous nature and wide range of substrates. Therefore, targeting APP-secretase interactions could be a novel treatment strategy for AD. Colocalization of APP species with BACE1 in a novel model of low- versus high-Aβ secretion-Two genetically identical human iPSC-derived neuronal cell types: low Aβ-secreting neuroprogenitor cells (NPCs) and high Aβ secreting mature neurons, were compared. Increased full-length APP (flAPP)/BACE1 colocalization in early endosomes was seen in neurons, while APP-CTF/BACE1 colocalization was much higher than flAPP/BACE1 colocalization in NPCs, although the cellular location was not determined.
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Affiliation(s)
- Sandra Roselli
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Blå Stråket 15, Sahlgrenska Hospital, 405 30, Gothenburg, Sweden.
| | - Tugce Munise Satir
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Blå Stråket 15, Sahlgrenska Hospital, 405 30, Gothenburg, Sweden
| | - Rafael Camacho
- Centre for Cellular Imaging, Core Facilities, The Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 7A, 405 30, Gothenburg, Sweden
| | - Stefanie Fruhwürth
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Blå Stråket 15, Sahlgrenska Hospital, 405 30, Gothenburg, Sweden
| | - Petra Bergström
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Blå Stråket 15, Sahlgrenska Hospital, 405 30, Gothenburg, Sweden
| | - Henrik Zetterberg
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Blå Stråket 15, Sahlgrenska Hospital, 405 30, Gothenburg, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Building V3, Mölndal Hospital, 431 80, Mölndal, Sweden
- Department of Neurodegenerative Disease, Institute of Neurology, University College London Queen Square, Queen Square, London, WC1N 3BG, UK
- UK Dementia Research Institute at UCL, Cruciform Building, Gower Street, London, WC1E 6BT, UK
- Hong Kong Center for Neurodegenerative Diseases, Units 1501-1502, 1512-1518, 15/F, Building 17W, Hong Kong Science Park, Shatin, N.T., Hong Kong, China
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, 53792, USA
| | - Lotta Agholme
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Blå Stråket 15, Sahlgrenska Hospital, 405 30, Gothenburg, Sweden
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3
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Orobets KS, Karamyshev AL. Amyloid Precursor Protein and Alzheimer's Disease. Int J Mol Sci 2023; 24:14794. [PMID: 37834241 PMCID: PMC10573485 DOI: 10.3390/ijms241914794] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/20/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023] Open
Abstract
Alzheimer's disease (AD) is one of the most common neurodegenerative disorders associated with age or inherited mutations. It is characterized by severe dementia in the late stages that affect memory, cognitive functions, and daily life overall. AD progression is linked to the accumulation of cytotoxic amyloid beta (Aβ) and hyperphosphorylated tau protein combined with other pathological features such as synaptic loss, defective energy metabolism, imbalances in protein, and metal homeostasis. Several treatment options for AD are under investigation, including antibody-based therapy and stem cell transplantation. Amyloid precursor protein (APP) is a membrane protein considered to play a main role in AD pathology. It is known that APP in physiological conditions follows a non-amyloidogenic pathway; however, it can proceed to an amyloidogenic scenario, which leads to the generation of extracellular deleterious Aβ plaques. Not all steps of APP biogenesis are clear so far, and these questions should be addressed in future studies. AD is a complex chronic disease with many factors that contribute to disease progression.
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Affiliation(s)
| | - Andrey L. Karamyshev
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA;
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Latina V, Atlante A, Malerba F, La Regina F, Balzamino BO, Micera A, Pignataro A, Stigliano E, Cavallaro S, Calissano P, Amadoro G. The Cleavage-Specific Tau 12A12mAb Exerts an Anti-Amyloidogenic Action by Modulating the Endocytic and Bioenergetic Pathways in Alzheimer's Disease Mouse Model. Int J Mol Sci 2023; 24:ijms24119683. [PMID: 37298634 DOI: 10.3390/ijms24119683] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/27/2023] [Accepted: 05/31/2023] [Indexed: 06/12/2023] Open
Abstract
Beyond deficits in hippocampal-dependent episodic memory, Alzheimer's Disease (AD) features sensory impairment in visual cognition consistent with extensive neuropathology in the retina. 12A12 is a monoclonal cleavage specific antibody (mAb) that in vivo selectively neutralizes the AD-relevant, harmful N-terminal 20-22 kDa tau fragment(s) (i.e., NH2htau) without affecting the full-length normal protein. When systemically injected into the Tg2576 mouse model overexpressing a mutant form of Amyloid Precursor Protein (APP), APPK670/671L linked to early onset familial AD, this conformation-specific tau mAb successfully reduces the NH2htau accumulating both in their brain and retina and, thus, markedly alleviates the phenotype-associated signs. By means of a combined biochemical and metabolic experimental approach, we report that 12A12mAb downregulates the steady state expression levels of APP and Beta-Secretase 1 (BACE-1) and, thus, limits the Amyloid beta (Aβ) production both in the hippocampus and retina from this AD animal model. The local, antibody-mediated anti-amyloidogenic action is paralleled in vivo by coordinated modulation of the endocytic (BIN1, RIN3) and bioenergetic (glycolysis and L-Lactate) pathways. These findings indicate for the first time that similar molecular and metabolic retino-cerebral pathways are modulated in a coordinated fashion in response to 12A12mAb treatment to tackle the neurosensorial Aβ accumulation in AD neurodegeneration.
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Affiliation(s)
- Valentina Latina
- European Brain Research Institute (EBRI), Viale Regina Elena 295, 00161 Rome, Italy
| | - Anna Atlante
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council (CNR), Via Amendola 122/O, 70126 Bari, Italy
| | - Francesca Malerba
- European Brain Research Institute (EBRI), Viale Regina Elena 295, 00161 Rome, Italy
| | - Federico La Regina
- European Brain Research Institute (EBRI), Viale Regina Elena 295, 00161 Rome, Italy
| | - Bijorn Omar Balzamino
- Research Laboratories in Ophthalmology, IRCCS-Fondazione Bietti, Via Santo Stefano Rotondo 6, 00184 Rome, Italy
| | - Alessandra Micera
- Research Laboratories in Ophthalmology, IRCCS-Fondazione Bietti, Via Santo Stefano Rotondo 6, 00184 Rome, Italy
| | - Annabella Pignataro
- Institute of Translational Pharmacology (IFT), National Research Council (CNR), Via Fosso del Cavaliere 100, 00133 Rome, Italy
| | - Egidio Stigliano
- Area of Pathology, Department of Woman and Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli IRCCS, Istituto di Anatomia Patologica, Università Cattolica del Sacro Cuore, Largo Francesco Vito 1, 00168 Rome, Italy
| | - Sebastiano Cavallaro
- Institute for Biomedical Research and Innovation (IRIB), National Research Council (CNR), Via P. Gaifami 18, 95126 Catania, Italy
| | - Pietro Calissano
- European Brain Research Institute (EBRI), Viale Regina Elena 295, 00161 Rome, Italy
| | - Giuseppina Amadoro
- European Brain Research Institute (EBRI), Viale Regina Elena 295, 00161 Rome, Italy
- Institute of Translational Pharmacology (IFT), National Research Council (CNR), Via Fosso del Cavaliere 100, 00133 Rome, Italy
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5
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Wen QX, Luo B, Xie XY, Zhou GF, Chen J, Song L, Liu Y, Xie SQ, Chen L, Li KY, Xiang XJ, Chen GJ. AP2S1 regulates APP degradation through late endosome-lysosome fusion in cells and APP/PS1 mice. Traffic 2023; 24:20-33. [PMID: 36412210 PMCID: PMC10107530 DOI: 10.1111/tra.12874] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 09/08/2022] [Accepted: 11/14/2022] [Indexed: 11/23/2022]
Abstract
AP2S1 is the sigma 2 subunit of adaptor protein 2 (AP2) that is essential for endocytosis. In this study, we investigated the potential role of AP2S1 in intracellular processing of amyloid precursor protein (APP), which contributes to the pathogenesis of Alzheimer disease (AD) by generating the toxic β-amyloid peptide (Aβ). We found that knockdown or overexpression of AP2S1 decreased or increased the protein levels of APP and Aβ in cells stably expressing human full-length APP695, respectively. This effect was unrelated to endocytosis but involved lysosomal degradation. Morphological studies revealed that silencing of AP2S1 promoted the translocalization of APP from RAB9-positive late endosomes (LE) to LAMP1-positive lysosomes, which was paralleled by the enhanced LE-lysosome fusion. In support, silencing of vacuolar protein sorting-associated protein 41 (VPS41) that is implicated in LE-lyso fusion prevented AP2S1-mediated regulation of APP degradation and translocalization. In APP/PS1 mice, an animal model of AD, AAV-mediated delivery of AP2S1 shRNA in the hippocampus significantly reduced the protein levels of APP and Aβ, with the concomitant APP translocalization, LE-lyso fusion and the improved cognitive functions. Taken together, these data uncover a LE-lyso fusion mechanism in APP degradation and suggest a novel role for AP2S1 in the pathophysiology of AD.
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Affiliation(s)
- Qi-Xin Wen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Biao Luo
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xiao-Yong Xie
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Gui-Feng Zhou
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Jian Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Li Song
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Yue Liu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Shi-Qi Xie
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Long Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Kun-Yi Li
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xiao-Jiao Xiang
- Department of Nuclear Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Guo-Jun Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Chongqing Key Laboratory of Neurology, Chongqing, China.,Institute for Brain Science and Disease, Chongqing Medical University, Chongqing, China
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6
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Aow J, Huang TR, Thinakaran G, Koo EH. Enhanced cleavage of APP by co-expressed Bace1 alters the distribution of APP and its fragments in neuronal and non-neuronal cells. Mol Neurobiol 2022; 59:3073-3090. [PMID: 35266114 DOI: 10.1007/s12035-022-02733-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/04/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND Alzheimer's disease amyloid-beta peptides (Aβ) are generated via sequential cleavage of the amyloid precursor protein (APP) by β-secretase (Bace1) and γ-secretase. Though the precise subcellular location(s) of Bace1-mediated APP cleavage remains unresolved, current models suggest APP internalization into Bace1-containing endosomes is a critical step. However, direct evidence for this model is lacking, and previous reports that probed the APP/Bace1 interaction (using co-expressed APP and Bace1 differentially labeled with fluorescent protein tags) did not determine if APP fluorescence originated from full-length APP (fl-APP) molecules that had internalized from the cell surface pool. METHODS We adapted the bungarotoxin-ligand (BTX) system to label surface APP and track internalized fluorescent APP/BTX puncta in rodent primary neurons co-expressing fluorescently-tagged Bace1. Subsequently, we employed imaging and biochemical-based approaches to measure N- and C-terminal APP epitope levels in primary neurons, N2a neuroblastoma, and HeLa cell lines. RESULTS We hypothesized that surface-labeled APP/BTX puncta would, upon internalization, colocalize with fluorescently-tagged Bace1. Unexpectedly, we observed a dramatic loss of internalized APP in co-transfected neurons and ~ 80-90% loss of surface-resident fl-APP, which we also observed in HeLa and N2a cells. Loss of surface fl-APP could be reversed by a Bace1 inhibitor, suggesting that enhanced Bace1-mediated APP cleavage was responsible for the altered processing and mis-sorting. Importantly, in a C-terminally-tagged APP construct, the majority of C-terminal fluorescence was preserved in HeLa cells despite the loss of N-terminal APP signal. This phenomenon was not only recapitulated in cultured neurons, but also showed a progressive disappearance of the APP N-terminal tag, reflecting continual cleavage of fl-APP by Bace1 away from the cell body. CONCLUSIONS Our results strongly suggested that in APP/Bace1 co-expression approaches, there was significant early and aberrant Bace1-mediated APP cleavage that perturbed fl-APP trafficking from the secretory pathway onwards, resulting in a substantial loss of surface fl-APP, which in turn led to a marked reduction in APP internalization. In C-terminally-tagged APP constructs, a large fraction of the APP fluorescence signal therefore likely arose from fluorescently-tagged β-C-terminal-fragment (β-CTF) or downstream proteolytic derivatives instead of fl-APP. Thus, care is needed in interpreting results where APP is detected only with a C-terminal tag in the presence of Bace1 co-expression, and previous findings may need to be reinterpreted if it is unclear whether fl-APP is present in normal physiological levels.
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Affiliation(s)
- Jonathan Aow
- Agency for Science, Technology and Research (A*STAR), Genome Institute of Singapore, Singapore, Singapore.
- Department of Medicine, National University of Singapore, Singapore, Singapore.
| | - Tzu-Rung Huang
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | - Gopal Thinakaran
- USF Health Byrd Alzheimer's Center and Research Institute and Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Edward H Koo
- Department of Medicine, National University of Singapore, Singapore, Singapore.
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore.
- Department of Neurosciences, University of California San Diego, San Diego, CA, USA.
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7
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Rab35 and glucocorticoids regulate APP and BACE1 trafficking to modulate Aβ production. Cell Death Dis 2021; 12:1137. [PMID: 34876559 PMCID: PMC8651661 DOI: 10.1038/s41419-021-04433-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/08/2021] [Accepted: 11/23/2021] [Indexed: 11/08/2022]
Abstract
Chronic stress and elevated glucocorticoids (GCs), the major stress hormones, are risk factors for Alzheimer’s disease (AD) and promote AD pathomechanisms, including overproduction of toxic amyloid-β (Aβ) peptides and intraneuronal accumulation of hyperphosphorylated Tau protein. The latter is linked to downregulation of the small GTPase Rab35, which mediates Tau degradation via the endolysosomal pathway. Whether Rab35 is also involved in Aβ overproduction remains an open question. Here, we find that hippocampal Rab35 levels are decreased not only by stress/GC but also by aging, another AD risk factor. Moreover, we show that Rab35 negatively regulates Aβ production by sorting amyloid precursor protein (APP) and β-secretase (BACE1) out of the endosomal network, where they interact to produce Aβ. Interestingly, Rab35 coordinates distinct intracellular trafficking steps for BACE1 and APP, mediated by its effectors OCRL and ACAP2, respectively. Finally, we demonstrate that Rab35 overexpression prevents the amyloidogenic trafficking of APP and BACE1 induced by high GC levels. These studies identify Rab35 as a key regulator of APP processing and suggest that its downregulation may contribute to stress-related and AD-related amyloidogenesis.
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8
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Cuestas Torres DM, Cardenas FP. Synaptic plasticity in Alzheimer's disease and healthy aging. Rev Neurosci 2021; 31:245-268. [PMID: 32250284 DOI: 10.1515/revneuro-2019-0058] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 11/01/2019] [Indexed: 12/17/2022]
Abstract
The strength and efficiency of synaptic connections are affected by the environment or the experience of the individual. This property, called synaptic plasticity, is directly related to memory and learning processes and has been modeled at the cellular level. These types of cellular memory and learning models include specific stimulation protocols that generate a long-term strengthening of the synapses, called long-term potentiation, or a weakening of the said long-term synapses, called long-term depression. Although, for decades, researchers have believed that the main cause of the cognitive deficit that characterizes Alzheimer's disease (AD) and aging was the loss of neurons, the hypothesis of an imbalance in the cellular and molecular mechanisms of synaptic plasticity underlying this deficit is currently widely accepted. An understanding of the molecular and cellular changes underlying the process of synaptic plasticity during the development of AD and aging will direct future studies to specific targets, resulting in the development of much more efficient and specific therapeutic strategies. In this review, we classify, discuss, and describe the main findings related to changes in the neurophysiological mechanisms of synaptic plasticity in excitatory synapses underlying AD and aging. In addition, we suggest possible mechanisms in which aging can become a high-risk factor for the development of AD and how its development could be prevented or slowed.
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Affiliation(s)
- Diana Marcela Cuestas Torres
- Departamento de Psicología and Departamento de Biología, Laboratorio de Neurociencia y Comportamiento, Universidad de los Andes, Cra 1 N° 18A-12, CP 111711, Bogotá, Colombia
| | - Fernando P Cardenas
- Departamento de Psicología, Laboratorio de Neurociencia y Comportamiento, Universidad de los Andes, Cra 1 N° 18A-12, CP 111711, Bogotá, Colombia
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9
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Endocytosis-pathway polygenic scores affects the hippocampal network connectivity and individualized identification across the high-risk of Alzheimer's disease. Brain Imaging Behav 2021; 15:1155-1169. [PMID: 32803660 DOI: 10.1007/s11682-020-00316-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The neural mechanisms underlying the polygenic effects of the endocytosis pathway on the brain function of Alzheimer's Disease (AD) remain unclear, especially in the prodromal stages of AD from early mild cognitive impairment (EMCI) to late mild cognitive impairment (LMCI). We used an imaging genetic approach to investigate the polygenic effects of the endocytosis pathway on the hippocampal network across the prodromal stages of AD. The subjects' data were selected from the Alzheimer's Disease Neuroimaging Initiative. Hippocampal volumes were examined in subjects of cognitive normal (CN), EMCI and LMCI groups. Multivariate linear regression analysis was employed to measure the effects of disease and endocytosis-based multilocus genetic risk scores (MGRS) on the hippocampal network which was constructed using the bilateral hippocampal regions. We identified hippocampal volumes in LMCI group were smaller than those in CN and EMCI groups. Endocytosis-based MGRS was widely influenced the neural structures within the hippocampal network, especially in the prefrontal-occipital regions and striatum. Compared to low endocytosis-based MGRS carriers, high MGRS carriers showed the opposite trajectory of hippocampal network functional connectivity (FC) across the prodromal stages of AD. Further, a model composed of selected hippocampal FCs and hippocampal volume yielded strong classification powers of EMCI and LMCI. These findings expand our understanding of the pathophysiology of polygenic effects underlying brain network in the prodromal stages of AD.
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10
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Burrinha T, Martinsson I, Gomes R, Terrasso AP, Gouras GK, Almeida CG. Up-regulation of APP endocytosis by neuronal aging drives amyloid dependent-synapse loss. J Cell Sci 2021; 134:240244. [PMID: 33910234 DOI: 10.1242/jcs.255752] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/03/2021] [Indexed: 12/14/2022] Open
Abstract
Neuronal aging increases the risk of late-onset Alzheimer's disease. During normal aging, synapses decline, and β-amyloid (Aβ) accumulates intraneuronally. However, little is known about the underlying cell biological mechanisms. We studied normal neuronal aging using normal aged brain and aged mouse primary neurons that accumulate lysosomal lipofuscin and show synapse loss. We identify the up-regulation of amyloid precursor protein (APP) endocytosis as a neuronal aging mechanism that potentiates APP processing and Aβ production in vitro and in vivo. The increased APP endocytosis may contribute to the observed early endosomes enlargement in the aged brain. Mechanistically, we show that clathrin-dependent APP endocytosis requires F-actin and that clathrin and endocytic F-actin increase with neuronal aging. Finally, Aβ production inhibition reverts synaptic decline in aged neurons while Aβ accumulation, promoted by endocytosis up-regulation in younger neurons, recapitulates aging-related synapse decline. Overall, we identify APP endocytosis up-regulation as a potential mechanism of neuronal aging and, thus, a novel target to prevent late-onset Alzheimer's disease.
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Affiliation(s)
- Tatiana Burrinha
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, 1169-056 Lisboa,Portugal
| | - Isak Martinsson
- Experimental Dementia Research Unit, Lund University, 22184 Lund, Sweden
| | - Ricardo Gomes
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, 1169-056 Lisboa,Portugal.,iBET - Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Ana Paula Terrasso
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, 1169-056 Lisboa,Portugal.,iBET - Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Gunnar K Gouras
- Experimental Dementia Research Unit, Lund University, 22184 Lund, Sweden
| | - Cláudia Guimas Almeida
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, 1169-056 Lisboa,Portugal
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11
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Yi C, Goh KY, Wong LW, Ramanujan A, Tanaka K, Sajikumar S, Ibáñez CF. Inactive variants of death receptor p75 NTR reduce Alzheimer's neuropathology by interfering with APP internalization. EMBO J 2020; 40:e104450. [PMID: 33258176 DOI: 10.15252/embj.2020104450] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 01/04/2023] Open
Abstract
A prevalent model of Alzheimer's disease (AD) pathogenesis postulates the generation of neurotoxic fragments derived from the amyloid precursor protein (APP) after its internalization to endocytic compartments. The molecular pathways that regulate APP internalization and intracellular trafficking in neurons are incompletely understood. Here, we report that 5xFAD mice, an animal model of AD, expressing signaling-deficient variants of the p75 neurotrophin receptor (p75NTR ) show greater neuroprotection from AD neuropathology than animals lacking this receptor. p75NTR knock-in mice lacking the death domain or transmembrane Cys259 showed lower levels of Aβ species, amyloid plaque burden, gliosis, mitochondrial stress, and neurite dystrophy than global knock-outs. Strikingly, long-term synaptic plasticity and memory, which are completely disrupted in 5xFAD mice, were fully recovered in the knock-in mice. Mechanistically, we found that p75NTR interacts with APP at the plasma membrane and regulates its internalization and intracellular trafficking in hippocampal neurons. Inactive p75NTR variants internalized considerably slower than wild-type p75NTR and showed increased association with the recycling pathway, thereby reducing APP internalization and co-localization with BACE1, the critical protease for generation of neurotoxic APP fragments, favoring non-amyloidogenic APP cleavage. These results reveal a novel pathway that directly and specifically regulates APP internalization, amyloidogenic processing, and disease progression, and suggest that inhibitors targeting the p75NTR transmembrane domain may be an effective therapeutic strategy in AD.
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Affiliation(s)
- Chenju Yi
- Department of Physiology, National University of Singapore, Singapore City, Singapore.,Life Sciences Institute, National University of Singapore, Singapore City, Singapore
| | - Ket Yin Goh
- Department of Physiology, National University of Singapore, Singapore City, Singapore.,Life Sciences Institute, National University of Singapore, Singapore City, Singapore
| | - Lik-Wei Wong
- Department of Physiology, National University of Singapore, Singapore City, Singapore.,Life Sciences Institute, National University of Singapore, Singapore City, Singapore
| | - Ajeena Ramanujan
- Department of Physiology, National University of Singapore, Singapore City, Singapore.,Life Sciences Institute, National University of Singapore, Singapore City, Singapore
| | - Kazuhiro Tanaka
- Department of Physiology, National University of Singapore, Singapore City, Singapore.,Life Sciences Institute, National University of Singapore, Singapore City, Singapore
| | - Sreedharan Sajikumar
- Department of Physiology, National University of Singapore, Singapore City, Singapore.,Life Sciences Institute, National University of Singapore, Singapore City, Singapore
| | - Carlos F Ibáñez
- Department of Physiology, National University of Singapore, Singapore City, Singapore.,Life Sciences Institute, National University of Singapore, Singapore City, Singapore.,Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.,Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch, South Africa
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12
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Hu L, Chen L, Yang L, Ye Z, Huang W, Li X, Liu Q, Qiu J, Ding X. KCTD1 mutants in scalp‑ear‑nipple syndrome and AP‑2α P59A in Char syndrome reciprocally abrogate their interactions, but can regulate Wnt/β‑catenin signaling. Mol Med Rep 2020; 22:3895-3903. [PMID: 33000225 PMCID: PMC7533495 DOI: 10.3892/mmr.2020.11457] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 07/14/2020] [Indexed: 12/26/2022] Open
Abstract
Potassium-channel tetramerization-domain-containing 1 (KCTD1) mutations are reported to result in scalp-ear-nipple syndrome. These mutations occur in the conserved broad-complex, tramtrack and bric a brac domain, which is associated with inhibited transcriptional activity. However, the mechanisms of KCTD1 mutants have not previously been elucidated; thus, the present study aimed to investigate whether KCTD1 mutants affect their interaction with transcription factor AP-2α and their regulation of the Wnt pathway. Results from the present study demonstrated that none of the ten KCTD1 mutants had an inhibitory effect on the transcriptional activity of AP-2α. Co-immunoprecipitation assays demonstrated that certain mutants exhibited changeable localization compared with the nuclear localization of wild-type KCTD1, but no KCTD1 mutant interacted with AP-2α. Almost all KCTD1 mutants, except KCTD1 A30E and H33Q, exhibited differential inhibitory effects on regulating TOPFLASH luciferase reporter activity. In addition, the interaction region of KCTD1 to the PY motif (amino acids 59–62) in AP-2α was identified. KCTD1 exhibited no suppressive effects on the transcriptional activity of the AP-2α P59A mutant, resulting in Char syndrome, a genetic disorder characterized by a distinctive facial appearance, heart defect and hand abnormalities, by altered protein cellular localization that abolished protein interactions. However, the P59A, P60A, P61R and 4A AP-2α mutants inhibited TOPFLASH reporter activity. Moreover, AP-2α and KCTD1 inhibited β-catenin expression levels and SW480 cell viability. The present study thus identified a putative mechanism of disease-related KCTD1 mutants and AP-2α mutants by disrupting their interaction with the wildtype proteins AP-2α and KCTD1 and influencing the regulation of the Wnt/β-catenin pathway.
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Affiliation(s)
- Lingyu Hu
- Department of Obstetrics and Gynecology, Third Xiangya Hospital of The Central South University, Changsha, Hunan 410013, P.R. China
| | - Li Chen
- Key Laboratory of Protein Chemistry and Development Biology of State Education Ministry of China, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P.R. China
| | - Liu Yang
- Key Laboratory of Protein Chemistry and Development Biology of State Education Ministry of China, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P.R. China
| | - Zi Ye
- Yali High School of Changsha, Changsha, Hunan 410007, P.R. China
| | - Wenhuan Huang
- Key Laboratory of Protein Chemistry and Development Biology of State Education Ministry of China, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P.R. China
| | - Xinxin Li
- Key Laboratory of Protein Chemistry and Development Biology of State Education Ministry of China, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P.R. China
| | - Qing Liu
- Key Laboratory of Protein Chemistry and Development Biology of State Education Ministry of China, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P.R. China
| | - Junlu Qiu
- Key Laboratory of Protein Chemistry and Development Biology of State Education Ministry of China, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P.R. China
| | - Xiaofeng Ding
- Key Laboratory of Protein Chemistry and Development Biology of State Education Ministry of China, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P.R. China
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13
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Kurihara T, Asahi T, Sawamura N. Cereblon-mediated degradation of the amyloid precursor protein via the ubiquitin-proteasome pathway. Biochem Biophys Res Commun 2020; 524:236-241. [DOI: 10.1016/j.bbrc.2020.01.078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 01/15/2020] [Indexed: 11/30/2022]
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14
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Inhibitory effects of curcumin on H 2O 2-induced cell damage and APP expression and processing in SH-SY5Y cells transfected with APP gene with Swedish mutation. Mol Biol Rep 2020; 47:2047-2059. [PMID: 32036572 DOI: 10.1007/s11033-020-05305-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/04/2020] [Indexed: 10/25/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder, and the pathological mechanism of the disease is still far to understand. According to the amyloid cascade hypothesis in AD, Amyloid-β (Aβ) is considered as a key substance that contributes AD development. Aβ is a β-cleaving product from Amyloid-β protein precursor (APP). Mutations of APP including APPKM670/671670NL (Swedish mutation) result in Aβ overproduction and the development of early-onset familial AD. Increase of oxidative stress and damage also occurs in early stage of AD. In this study, we used a SH-SY5Y cell line that stably expresses APP gene with Swedish mutation (SH-SY5Y-APPswe), and the inhibitory effects of curcumin on H2O2-induced cell damage and APP processing were investigated. Cells were treated with curcumin (0 ~ 5 μM) for 4 h before hydrogen peroxide (H2O2). Cell growth was detected with CCK-8 assay, and cell damage was determined through the evaluation of release of lactate dehydrogenase (LDH) from the cytosol to the culture medium and the morphological change of nucleus. The ability of mitochondrial stress and the depolarization of mitochondrial membrane potential were assayed through the measuring the oxygen consumption rate (OCR) and the green/red fluorescence ratio of JC-1 dye respectively. The protein levels of APP, sAPPα, sAPPβ, and BACE1 were analyzed with Western blot assay. Aβ production was measured with enzyme-linked immunosorbent assay (ELISA). The results indicated that curcumin inhibits H2O2-induced decrease of cell growth and cell damage. Curcumin attenuates H2O2-induced damage on the ability to mitochondrial oxidative phosphorylation and membrane potential. Curcumin inhibits H2O2-induced increase of APP cleavage through β-cleavage pathway and of intracellular Aβ production. These results imply that curcumin can be used to treat AD through inhibiting oxidative damage-induced APP β-cleavage and intracellular Aβ generation.
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15
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Donepezil modulates amyloid precursor protein endocytosis and reduction by up-regulation of SNX33 expression in primary cortical neurons. Sci Rep 2019; 9:11922. [PMID: 31417133 PMCID: PMC6695423 DOI: 10.1038/s41598-019-47462-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 07/16/2019] [Indexed: 11/09/2022] Open
Abstract
Donepezil, a therapeutic drug for Alzheimer’s disease, ameliorates cognitive dysfunction through selective inhibition of acetylcholinesterase. However, recent studies have also reported off-target effects of donepezil that likely contribute to its therapeutic effects. In this study, we investigated the (i) role of donepezil in amyloid precursor protein (APP) processing and (ii) involvement of sorting nexin protein 33 (SNX33), a member of the sorting nexin protein family, in this processing. Results showed that donepezil induces an increase in SNX33 expression in primary cortical neurons. The secretion of sAPPα in culture media increased, whereas the expression of full-length APP in the cell lysate remained unchanged. Exposure of cortical cultures to donepezil led to a decrease in amyloid β (Aβ) protein levels in a concentration- and time-dependent manner. This decrease was not affected by concomitant treatment with acetylcholine receptor antagonists. SNX33 knockdown by target-specific morpholino oligos inhibited the effects of donepezil. Donepezil treatment increased cell membrane surface expression of APP in SNX33 expression-dependent manner. These results suggested that donepezil decreases the level of Aβ by increasing SNX33 expression and APP cleavage by α-secretase in cortical neurons.
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16
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Regulatory role of Golgi brefeldin A resistance factor‐1 in amyloid precursor protein trafficking, cleavage and Aβ formation. J Cell Biochem 2019; 120:15604-15615. [DOI: 10.1002/jcb.28827] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 01/11/2019] [Accepted: 01/14/2019] [Indexed: 01/19/2023]
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17
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Chun YS, Kwon OH, Oh HG, Cho YY, Yang HO, Chung S. Justicidin A Reduces β-Amyloid via Inhibiting Endocytosis of β-Amyloid Precursor Protein. Biomol Ther (Seoul) 2019; 27:276-282. [PMID: 30332887 PMCID: PMC6513189 DOI: 10.4062/biomolther.2018.112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/08/2018] [Accepted: 09/01/2018] [Indexed: 11/05/2022] Open
Abstract
β-amyloid precursor protein (APP) can be cleaved by α-, and γ-secretase at plasma membrane producing soluble ectodomain fragment (sAPPα). Alternatively, following endocytosis, APP is cleaved by β-, and γ-secretase at early endosomes generating β-amyloid (Aβ), the main culprit in Alzheimer's disease (AD). Thus, APP endocytosis is critical for Aβ production. Recently, we reported that Monsonia angustifolia, the indigenous vegetables consumed in Tanzania, improved cognitive function and decreased Aβ production. In this study, we examined the underlying mechanism of justicidin A, the active compound of M. angustifolia, on Aβ production. We found that justicidin A reduced endocytosis of APP, increasing sAPPα level, while decreasing Aβ level in HeLa cells overexpressing human APP with the Swedish mutation. The effect of justicidin A on Aβ production was blocked by endocytosis inhibitors, indicating that the decreased APP endocytosis by justicidin A is the underlying mechanism. Thus, justicidin A, the active compound of M. angustifolia, may be a novel agent for AD treatment.
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Affiliation(s)
- Yoon Sun Chun
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea.,Natural Products Research Center, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Oh-Hoon Kwon
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Hyun Geun Oh
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Yoon Young Cho
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Hyun Ok Yang
- Natural Products Research Center, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea.,Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Republic of Korea
| | - Sungkwon Chung
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
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18
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Komura H, Kakio S, Sasahara T, Arai Y, Takino N, Sato M, Satomura K, Ohnishi T, Nabeshima YI, Muramatsu SI, Kii I, Hoshi M. Alzheimer Aβ Assemblies Accumulate in Excitatory Neurons upon Proteasome Inhibition and Kill Nearby NAKα3 Neurons by Secretion. iScience 2019; 13:452-477. [PMID: 30827871 PMCID: PMC6443839 DOI: 10.1016/j.isci.2019.01.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 11/14/2018] [Accepted: 01/11/2019] [Indexed: 12/11/2022] Open
Abstract
We identified ∼30-mer amyloid-β protein (Aβ) assemblies, termed amylospheroids, from brains of patients with Alzheimer disease (AD) as toxic entities responsible for neurodegeneration and showed that Na+,K+-ATPase α3 (NAKα3) is the sole target of amylospheroid-mediated neurodegeneration. However, it remains unclear where in neurons amylospheroids form and how they reach their targets to induce neurodegeneration. Here, we present an in vitro culture system designed to chronologically follow amylospheroid formation in mature neurons expressing amyloid precursor protein bearing early-onset AD mutations. Amylospheroids were found to accumulate mainly in the trans-Golgi network of excitatory neurons and were initially transported in axons. Proteasome inhibition dramatically increased amylospheroid amounts in trans-Golgi by increasing Aβ levels and induced dendritic transport. Amylospheroids were secreted and caused the degeneration of adjacent NAKα3-expressing neurons. Interestingly, the ASPD-producing neurons later died non-apoptotically. Our findings demonstrate a link between ASPD levels and proteasome function, which may have important implications for AD pathophysiology.
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Affiliation(s)
- Hitomi Komura
- Department of Brain and Neurodegenerative Disease Research, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan; TAO Health Life Pharma Co., Ltd., Med-Pharma Collaboration Bldg, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shota Kakio
- Department of Brain and Neurodegenerative Disease Research, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan; TAO Health Life Pharma Co., Ltd., Med-Pharma Collaboration Bldg, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tomoya Sasahara
- Department of Brain and Neurodegenerative Disease Research, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan; TAO Health Life Pharma Co., Ltd., Med-Pharma Collaboration Bldg, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yoshie Arai
- Department of Brain and Neurodegenerative Disease Research, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan; TAO Health Life Pharma Co., Ltd., Med-Pharma Collaboration Bldg, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Naomi Takino
- Division of Neurology, Jichi Medical University, Shimotsuke 329-0498, Japan
| | - Michio Sato
- Meiji University, Graduate School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Kaori Satomura
- Department of Brain and Neurodegenerative Disease Research, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan; TAO Health Life Pharma Co., Ltd., Med-Pharma Collaboration Bldg, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Takayuki Ohnishi
- Department of Brain and Neurodegenerative Disease Research, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan; TAO Health Life Pharma Co., Ltd., Med-Pharma Collaboration Bldg, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yo-Ichi Nabeshima
- Department of Gerontology, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan
| | - Shin-Ichi Muramatsu
- Division of Neurology, Jichi Medical University, Shimotsuke 329-0498, Japan; Center for Gene & Cell Therapy, The Institute of Medical Science, University of Tokyo, Tokyo 108-0071, Japan
| | - Isao Kii
- RIKEN Center for Life Science Technologies, Division of Bio-Function Dynamics Imaging, Kobe 650-0047, Japan
| | - Minako Hoshi
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
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19
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Patel AA, Ganepola GA, Rutledge JR, Chang DH. The Potential Role of Dysregulated miRNAs in Alzheimer’s Disease Pathogenesis and Progression. J Alzheimers Dis 2019; 67:1123-1145. [DOI: 10.3233/jad-181078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Ankur A. Patel
- Department of Research, Center for Cancer Research and Genomic Medicine, The Valley Hospital, Paramus, NJ, USA
| | - Ganepola A.P. Ganepola
- Department of Research, Center for Cancer Research and Genomic Medicine, The Valley Hospital, Paramus, NJ, USA
| | - John R. Rutledge
- Department of Oncology Special Program, The Daniel and Gloria Blumenthal Cancer Center, The Valley Hospital, Paramus, NJ, USA
| | - David H. Chang
- Department of Research, Center for Cancer Research and Genomic Medicine, The Valley Hospital, Paramus, NJ, USA
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20
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Buechler J, Salinas PC. Deficient Wnt Signaling and Synaptic Vulnerability in Alzheimer's Disease: Emerging Roles for the LRP6 Receptor. Front Synaptic Neurosci 2018; 10:38. [PMID: 30425633 PMCID: PMC6218458 DOI: 10.3389/fnsyn.2018.00038] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/10/2018] [Indexed: 12/11/2022] Open
Abstract
Synapse dysfunction and loss represent critical early events in the pathophysiology of Alzheimer’s disease (AD). While extensive research has elucidated the direct synaptotoxic effects of Amyloid-β (Aβ) oligomers, less is known about how signaling pathways at the synapse are affected by Aβ. A better understanding of the cellular and molecular mechanisms underlying synaptic vulnerability in AD is key to illuminating the determinants of AD susceptibility and will unveil novel therapeutic avenues. Canonical Wnt signaling through the Wnt co-receptor LRP6 has a critical role in maintaining the structural and functional integrity of synaptic connections in the adult brain. Accumulating evidence suggests that deficient Wnt signaling may contribute to AD pathology. In particular, LRP6 deficiency compromises synaptic function and stability, and contributes to Aß production and plaque formation. Here, we review the role of Wnt signaling for synaptic maintenance in the adult brain and the contribution of aberrant Wnt signaling to synaptic degeneration in AD. We place a focus on emerging evidence implicating the LRP6 receptor as an important modulator of AD risk and pathology.
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Affiliation(s)
- Johanna Buechler
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Patricia C Salinas
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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21
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Lichtenthaler SF, Lemberg MK, Fluhrer R. Proteolytic ectodomain shedding of membrane proteins in mammals-hardware, concepts, and recent developments. EMBO J 2018; 37:e99456. [PMID: 29976761 PMCID: PMC6068445 DOI: 10.15252/embj.201899456] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/05/2018] [Accepted: 06/18/2018] [Indexed: 12/14/2022] Open
Abstract
Proteolytic removal of membrane protein ectodomains (ectodomain shedding) is a post-translational modification that controls levels and function of hundreds of membrane proteins. The contributing proteases, referred to as sheddases, act as important molecular switches in processes ranging from signaling to cell adhesion. When deregulated, ectodomain shedding is linked to pathologies such as inflammation and Alzheimer's disease. While proteases of the "a disintegrin and metalloprotease" (ADAM) and "beta-site APP cleaving enzyme" (BACE) families are widely considered as sheddases, in recent years a much broader range of proteases, including intramembrane and soluble proteases, were shown to catalyze similar cleavage reactions. This review demonstrates that shedding is a fundamental process in cell biology and discusses the current understanding of sheddases and their substrates, molecular mechanisms and cellular localizations, as well as physiological functions of protein ectodomain shedding. Moreover, we provide an operational definition of shedding and highlight recent conceptual advances in the field. While new developments in proteomics facilitate substrate discovery, we expect that shedding is not a rare exception, but rather the rule for many membrane proteins, and that many more interesting shedding functions await discovery.
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Affiliation(s)
- Stefan F Lichtenthaler
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Neuroproteomics, Klinikum rechts der Isar, School of Medicine, and Institute for Advanced Study, Technical University Munich, Munich, Germany
- Munich Center for Systems Neurology (SyNergy), Munich, Germany
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Regina Fluhrer
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Biomedizinisches Centrum (BMC), Ludwig-Maximilians University of Munich, Munich, Germany
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22
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Xu S, Nigam SM, Brodin L. Overexpression of SNX3 Decreases Amyloid-β Peptide Production by Reducing Internalization of Amyloid Precursor Protein. NEURODEGENER DIS 2018; 18:26-37. [PMID: 29414832 DOI: 10.1159/000486199] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 12/08/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Sorting nexins (SNXs) have diverse functions in protein sorting and membrane trafficking. Recently, single-nucleotide polymorphisms in SNX3 were found to be associated with Alzheimer disease. However, it remains unknown whether SNX3 participates in amyloid (A)β peptide production. OBJECTIVE To examine the role of SNX3 in Aβ production and APP processing. METHODS The effect of increased expression of SNX3 was studied in HEK293T cells. Aβ peptides were measured by immunoassay. Protein-protein association was analyzed by a bimolecular fluorescence complementation (BiFC) assay. APP uptake was measured with an α-bungarotoxin-binding assay, and flow cytometry was used to measure cell surface APP levels. RESULTS We found that overexpression of SNX3 in HEK293T cells decreases the levels of secreted Aβ and soluble N-terminal APP fragments (sAPPβ). The reduction correlated with a decreased association of APP with BACE1, as revealed by BiFC. This effect may, in part, be explained by a reduced internalization of APP; SNX3 overexpression reduced APP internalization as determined by an α-bungarotoxin-binding assay, and caused increased APP levels on the cell surface, as shown by flow cytometry. In addition, SNX3 overexpression increased the cellular levels of full-length APP. CONCLUSION These results provide evidence that SNX3 regulates Aβ production by influencing the internalization of APP.
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Affiliation(s)
- Shaohua Xu
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Saket M Nigam
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Lennart Brodin
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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23
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Otero MG, Bessone IF, Hallberg AE, Cromberg LE, De Rossi MC, Saez TM, Levi V, Almenar-Queralt A, Falzone TL. Proteasome stress leads to APP axonal transport defects by promoting its amyloidogenic processing in lysosomes. J Cell Sci 2018; 131:jcs.214536. [DOI: 10.1242/jcs.214536] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 04/25/2018] [Indexed: 01/25/2023] Open
Abstract
Alzheimer Disease (AD) pathology includes the accumulation of poly-ubiquitinated proteins and failures in proteasome-dependent degradation. Whereas the distribution of proteasomes and its role in synaptic function have been studied, whether proteasome activity regulates the axonal transport and metabolism of the amyloid precursor protein (APP), remains elusive. Using live imaging in primary hippocampal neurons, we showed that proteasome inhibition rapidly and severely impairs the axonal transport of APP. Fluorescent cross-correlation analyses and membrane internalization blockage showed that plasma membrane APP do not contribute to transport defects. Moreover, by western blots and double-color APP imaging we demonstrated that proteasome inhibition precludes APP axonal transport by enhancing its endo-lysosomal delivery where β-cleavage is induced. Together, we found that proteasomes controls the distal transport of APP and can re-distribute Golgi-derived vesicles to the endo-lysosomal pathway. This crosstalk between proteasomes and lysosomes regulates APP intracellular dynamics, and defects in proteasome activity can be considered a contributing factor that lead to abnormal APP metabolism in AD.
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Affiliation(s)
- María Gabriela Otero
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - Ivan Fernandez Bessone
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - Alan Earle Hallberg
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - Lucas Eneas Cromberg
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - María Cecilia De Rossi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica-IQUIBICEN UBA-CONICET, CP1428EGA, Argentina
| | - Trinidad M. Saez
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
- Instituto de Biología y Medicina Experimental, IBYME (CONICET). Vuelta de obligado 2490, Buenos Aires, CP 1428, Argentina
| | - Valeria Levi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica-IQUIBICEN UBA-CONICET, CP1428EGA, Argentina
| | - Angels Almenar-Queralt
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Tomás Luis Falzone
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
- Instituto de Biología y Medicina Experimental, IBYME (CONICET). Vuelta de obligado 2490, Buenos Aires, CP 1428, Argentina
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Grimm MOW, Michaelson DM, Hartmann T. Omega-3 fatty acids, lipids, and apoE lipidation in Alzheimer's disease: a rationale for multi-nutrient dementia prevention. J Lipid Res 2017; 58:2083-2101. [PMID: 28528321 PMCID: PMC5665674 DOI: 10.1194/jlr.r076331] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/09/2017] [Indexed: 12/14/2022] Open
Abstract
In the last decade, it has become obvious that Alzheimer's disease (AD) is closely linked to changes in lipids or lipid metabolism. One of the main pathological hallmarks of AD is amyloid-β (Aβ) deposition. Aβ is derived from sequential proteolytic processing of the amyloid precursor protein (APP). Interestingly, both, the APP and all APP secretases are transmembrane proteins that cleave APP close to and in the lipid bilayer. Moreover, apoE4 has been identified as the most prevalent genetic risk factor for AD. ApoE is the main lipoprotein in the brain, which has an abundant role in the transport of lipids and brain lipid metabolism. Several lipidomic approaches revealed changes in the lipid levels of cerebrospinal fluid or in post mortem AD brains. Here, we review the impact of apoE and lipids in AD, focusing on the major brain lipid classes, sphingomyelin, plasmalogens, gangliosides, sulfatides, DHA, and EPA, as well as on lipid signaling molecules, like ceramide and sphingosine-1-phosphate. As nutritional approaches showed limited beneficial effects in clinical studies, the opportunities of combining different supplements in multi-nutritional approaches are discussed and summarized.
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Affiliation(s)
- Marcus O W Grimm
- Department of Experimental Neurology and Department of Neurodegeneration and Neurobiology, and Deutsches Institut für DemenzPrävention (DIDP), Saarland University, Homburg/Saar, Germany
| | - Daniel M Michaelson
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Tobias Hartmann
- Department of Experimental Neurology and Department of Neurodegeneration and Neurobiology, and Deutsches Institut für DemenzPrävention (DIDP), Saarland University, Homburg/Saar, Germany
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Alterations in endocytic protein expression with increasing age in the transgenic APP695 V717I London mouse model of amyloid pathology. Neuroreport 2017; 28:963-968. [DOI: 10.1097/wnr.0000000000000861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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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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Nie L, Wei G, Peng S, Qu Z, Yang Y, Yang Q, Huang X, Liu J, Zhuang Z, Yang X. Melatonin ameliorates anxiety and depression-like behaviors and modulates proteomic changes in triple transgenic mice of Alzheimer's disease. Biofactors 2017; 43:593-611. [PMID: 28608594 DOI: 10.1002/biof.1369] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 04/06/2017] [Accepted: 05/01/2017] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is a devastating neurodegenerative disease accompanied by neuropsychiatric symptoms, such as anxiety and depression. The levels of melatonin decrease in brains of AD patients. The potential effect of melatonin on anxiety and depression behaviors in AD and the underlying mechanisms remain unclear. In this study, we treated 10-month-old triple transgenic mice of AD (3xTg-AD) with melatonin (10 mg/kg body weight/day) for 1 month and explored the effects of melatonin on anxiety and depression-like behaviors in 3xTg-AD mice and the protein expression of hippocampal tissues. The behavioral test showed that melatonin ameliorated anxiety and depression-like behaviors of 3xTg-AD mice as measured by open field test, elevated plus maze test, forced swimming test, and tail suspension test. By carrying out two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry, we revealed a total of 46 differentially expressed proteins in hippocampus between the wild-type (WT) mice and non-treated 3xTg-AD mice. A total of 21 differentially expressed proteins were revealed in hippocampus between melatonin-treated and non-treated 3xTg-AD mice. Among these differentially expressed proteins, glutathione S-transferase P 1 (GSTP1) (an anxiety-associated protein) and complexin-1 (CPLX1) (a depression-associated protein) were significantly down-regulated in hippocampus of 3xTg-AD mice compared with the WT mice. The expression of these two proteins was modulated by melatonin treatment. Our study suggested that melatonin could be used as a potential candidate drug to improve the neuropsychiatric behaviors in AD via modulating the expression of the proteins (i.e. GSTP1 and CPLX1) involved in anxiety and depression behaviors. © 2017 BioFactors, 43(4):593-611, 2017.
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Affiliation(s)
- Lulin Nie
- College of Chemistry, Xiangtan University, Xiangtan, 411105, China
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Gang Wei
- Thyroid & Breast Surgery Department, Hubei Maternal & Children Hospital, Wuhan, 430070, China
| | - Shengming Peng
- College of Chemistry, Xiangtan University, Xiangtan, 411105, China
| | - Zhongsen Qu
- Department of Neurology, Shanghai Jiaotong University Affiliated the Sixth Hospital, Shanghai, 200233, China
| | - Ying Yang
- Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430070, China
| | - Qian Yang
- Department of cell biology and Anatomy, LSU Health Sciences Center, New Orleans, LA, 70112
| | - Xinfeng Huang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Jianjun Liu
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Zhixiong Zhuang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Xifei Yang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
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Grimm MOW, Mett J, Grimm HS, Hartmann T. APP Function and Lipids: A Bidirectional Link. Front Mol Neurosci 2017; 10:63. [PMID: 28344547 PMCID: PMC5344993 DOI: 10.3389/fnmol.2017.00063] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 02/24/2017] [Indexed: 12/14/2022] Open
Abstract
Extracellular neuritic plaques, composed of aggregated amyloid-β (Aβ) peptides, are one of the major histopathological hallmarks of Alzheimer's disease (AD), a progressive, irreversible neurodegenerative disorder and the most common cause of dementia in the elderly. One of the most prominent risk factor for sporadic AD, carrying one or two aberrant copies of the apolipoprotein E (ApoE) ε4 alleles, closely links AD to lipids. Further, several lipid classes and fatty acids have been reported to be changed in the brain of AD-affected individuals. Interestingly, the observed lipid changes in the brain seem not only to be a consequence of the disease but also modulate Aβ generation. In line with these observations, protective lipids being able to decrease Aβ generation and also potential negative lipids in respect to AD were identified. Mechanistically, Aβ peptides are generated by sequential proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretase. The α-secretase appears to compete with β-secretase for the initial cleavage of APP, preventing Aβ production. All APP-cleaving secretases as well as APP are transmembrane proteins, further illustrating the impact of lipids on Aβ generation. Beside the pathological impact of Aβ, accumulating evidence suggests that Aβ and the APP intracellular domain (AICD) play an important role in regulating lipid homeostasis, either by direct effects or by affecting gene expression or protein stability of enzymes involved in the de novo synthesis of different lipid classes. This review summarizes the current literature addressing the complex bidirectional link between lipids and AD and APP processing including lipid alterations found in AD post mortem brains, lipids that alter APP processing and the physiological functions of Aβ and AICD in the regulation of several lipid metabolism pathways.
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Affiliation(s)
- Marcus O. W. Grimm
- Experimental Neurology, Saarland UniversityHomburg/Saar, Germany
- Neurodegeneration and Neurobiology, Saarland UniversityHomburg/Saar, Germany
- Deutsches Institut für DemenzPrävention (DIDP), Saarland UniversityHomburg/Saar, Germany
| | - Janine Mett
- Experimental Neurology, Saarland UniversityHomburg/Saar, Germany
| | - Heike S. Grimm
- Experimental Neurology, Saarland UniversityHomburg/Saar, Germany
| | - Tobias Hartmann
- Experimental Neurology, Saarland UniversityHomburg/Saar, Germany
- Neurodegeneration and Neurobiology, Saarland UniversityHomburg/Saar, Germany
- Deutsches Institut für DemenzPrävention (DIDP), Saarland UniversityHomburg/Saar, Germany
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Bhowmick DC, Singh S, Trikha S, Jeremic AM. The Molecular Physiopathogenesis of Islet Amyloidosis. Handb Exp Pharmacol 2017; 245:271-312. [PMID: 29043504 DOI: 10.1007/164_2017_62] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human islet amyloid polypeptide or amylin (hA) is a 37-amino acid peptide hormone produced and co-secreted with insulin by pancreatic β-cells. Under physiological conditions, hA regulates a broad range of biological processes including insulin release and slowing of gastric emptying, thereby maintaining glucose homeostasis. However, under the pathological conditions associated with type 2 diabetes mellitus (T2DM), hA undergoes a conformational transition from soluble random coil monomers to alpha-helical oligomers and insoluble β-sheet amyloid fibrils or amyloid plaques. There is a positive correlation between hA oligomerization/aggregation, hA toxicity, and diabetes progression. Because the homeostatic balance between hA synthesis, release, and uptake is lost in diabetics and hA aggregation is a hallmark of T2DM, this chapter focuses on the biophysical and cell biology studies investigating molecular mechanisms of hA uptake, trafficking, and degradation in pancreatic cells and its relevance to h's toxicity. We will also discuss the regulatory role of endocytosis and proteolytic pathways in clearance of toxic hA species. Finally, we will discuss potential pharmacological approaches for specific targeting of hA trafficking pathways and toxicity in islet β-cells as potential new avenues toward treatments of T2DM patients.
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Affiliation(s)
| | - Sanghamitra Singh
- Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA
| | - Saurabh Trikha
- Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA
| | - Aleksandar M Jeremic
- Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA.
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Singh M, Jadhav HR, Bhatt T. Dynamin Functions and Ligands: Classical Mechanisms Behind. Mol Pharmacol 2016; 91:123-134. [PMID: 27879341 DOI: 10.1124/mol.116.105064] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 11/17/2016] [Indexed: 12/21/2022] Open
Abstract
Dynamin is a GTPase that plays a vital role in clathrin-dependent endocytosis and other vesicular trafficking processes by acting as a pair of molecular scissors for newly formed vesicles originating from the plasma membrane. Dynamins and related proteins are important components for the cleavage of clathrin-coated vesicles, phagosomes, and mitochondria. These proteins help in organelle division, viral resistance, and mitochondrial fusion/fission. Dysfunction and mutations in dynamin have been implicated in the pathophysiology of various disorders, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Charcot-Marie-Tooth disease, heart failure, schizophrenia, epilepsy, cancer, dominant optic atrophy, osteoporosis, and Down's syndrome. This review is an attempt to illustrate the dynamin-related mechanisms involved in the above-mentioned disorders and to help medicinal chemists to design novel dynamin ligands, which could be useful in the treatment of dynamin-related disorders.
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Affiliation(s)
- Mahaveer Singh
- Department of Pharmacy, Birla Institute of Technology and Sciences Pilani, Pilani Campus, Rajasthan, India
| | - Hemant R Jadhav
- Department of Pharmacy, Birla Institute of Technology and Sciences Pilani, Pilani Campus, Rajasthan, India
| | - Tanya Bhatt
- Department of Pharmacy, Birla Institute of Technology and Sciences Pilani, Pilani Campus, Rajasthan, India
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Thomas RS, Henson A, Gerrish A, Jones L, Williams J, Kidd EJ. Decreasing the expression of PICALM reduces endocytosis and the activity of β-secretase: implications for Alzheimer's disease. BMC Neurosci 2016; 17:50. [PMID: 27430330 PMCID: PMC4949774 DOI: 10.1186/s12868-016-0288-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/11/2016] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Polymorphisms in the gene for phosphatidylinositol binding clathrin assembly protein (PICALM), an endocytic-related protein, are associated with a small, increased risk of developing Alzheimer's disease (AD), strongly suggesting that changes in endocytosis are involved in the aetiology of the disease. We have investigated the involvement of PICALM in the processing of amyloid precursor protein (APP) to understand how PICALM could be linked to the development of AD. We used siRNA to deplete levels of PICALM, its isoforms and clathrin heavy chain in the human brain-derived H4 neuroglioma cell line that expresses endogenous levels of APP. We then used Western blotting, ELISA and immunohistochemistry to detect intra- and extracellular protein levels of endocytic-related proteins, APP and APP metabolites including β-amyloid (Aβ). Levels of functional endocytosis were quantified using ALEXA 488-conjugated transferrin and flow cytometry as a marker of clathrin-mediated endocytosis (CME). RESULTS Following depletion of all the isoforms of PICALM by siRNA in H4 cells, levels of intracellular APP, intracellular β-C-terminal fragment (β-CTF) and secreted sAPPβ (APP fragments produced by β-secretase cleavage) were significantly reduced but Aβ40 was not affected. Functional endocytosis was significantly reduced after both PICALM and clathrin depletion, highlighting the importance of PICALM in this process. However, depletion of clathrin did not affect APP but did reduce β-CTF levels. PICALM depletion altered the intracellular distribution of clathrin while clathrin reduction affected the subcellular pattern of PICALM labelling. Both PICALM and clathrin depletion reduced the expression of BACE1 mRNA and PICALM siRNA reduced protein levels. Individual depletion of PICALM isoforms 1 and 2 did not affect APP levels while clathrin depletion had a differential effect on the isoforms, increasing isoform 1 while decreasing isoform 2 expression. CONCLUSIONS The depletion of PICALM in brain-derived cells has significant effects on the processing of APP, probably by reducing CME. In particular, it affects the production of β-CTF which is increasingly considered to be an important mediator in AD independent of Aβ. Thus a decrease in PICALM expression in the brain could be beneficial to slow or prevent the development of AD.
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Affiliation(s)
- Rhian S. Thomas
- />School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB UK
| | - Alex Henson
- />School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB UK
| | - Amy Gerrish
- />MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ UK
- />West Midlands Regional Genetics Laboratory, Birmingham Women’s NHS Foundation Trust, Mindelsohn Way, Edgbaston, Birmingham, B15 2TG UK
| | - Lesley Jones
- />MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ UK
| | - Julie Williams
- />MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ UK
| | - Emma J. Kidd
- />School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB UK
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Alzheimer disease: modeling an Aβ-centered biological network. Mol Psychiatry 2016; 21:861-71. [PMID: 27021818 DOI: 10.1038/mp.2016.38] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/16/2016] [Accepted: 02/18/2016] [Indexed: 01/15/2023]
Abstract
In genetically complex diseases, the search for missing heritability is focusing on rare variants with large effect. Thanks to next generation sequencing technologies, genome-wide characterization of these variants is now feasible in every individual. However, a lesson from current studies is that collapsing rare variants at the gene level is often insufficient to obtain a statistically significant signal in case-control studies, and that network-based analyses are an attractive complement to classical approaches. In Alzheimer disease (AD), according to the prevalent amyloid cascade hypothesis, the pathology is driven by the amyloid beta (Aβ) peptide. In past years, based on experimental studies, several hundreds of proteins have been shown to interfere with Aβ production, clearance, aggregation or toxicity. Thanks to a manual curation of the literature, we identified 335 genes/proteins involved in this biological network and classified them according to their cellular function. The complete list of genes, or its subcomponents, will be of interest in ongoing AD genetic studies.
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Basagiannis D, Christoforidis S. Constitutive Endocytosis of VEGFR2 Protects the Receptor against Shedding. J Biol Chem 2016; 291:16892-903. [PMID: 27298320 DOI: 10.1074/jbc.m116.730309] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 12/19/2022] Open
Abstract
VEGFR2 plays a fundamental role in blood vessel formation and in life threatening diseases, such as cancer angiogenesis and cardiovascular disorders. Although inactive growth factor receptors are mainly localized at the plasma membrane, VEGFR2 undergoes constitutive endocytosis (in the absence of ligand) and recycling. Intriguingly, the significance of these futile transport cycles of VEGFR2 remains unclear. Here we found that, unexpectedly, the function of constitutive endocytosis of VEGFR2 is to protect the receptor against plasma membrane cleavage (shedding), thereby preserving the functional state of the receptor until the time of activation by VEGF. Inhibition of constitutive endocytosis of VEGFR2, by interference with the function of clathrin, dynamin, or Rab5, increases dramatically the cleavage/shedding of VEGFR2. Shedding of VEGFR2 produces an N-terminal soluble fragment (100 kDa, s100), which is released in the extracellular space, and a residual C-terminal part (130 kDa, p130) that remains integrated at the plasma membrane. The released soluble fragment (s100) co-immunoprecipitates with VEGF, in line with the topology of the VEGF-binding domain at the N terminus of VEGFR2. Increased shedding of VEGFR2 (via inhibition of constitutive endocytosis) results in reduced response to VEGF, consistently with the loss of the VEGF-binding domain from the membrane remnant of VEGFR2. These data suggest that constitutive internalization of VEGFR2 protects the receptor against shedding and provides evidence for an unprecedented mechanism via which endocytosis can regulate the fate and activity of growth factor receptors.
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Affiliation(s)
- Dimitris Basagiannis
- From the Institute of Molecular Biology and Biotechnology-Biomedical Research, Foundation for Research and Technology, 45110 Ioannina and the Department of Medicine, Laboratory of Biological Chemistry, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece
| | - Savvas Christoforidis
- From the Institute of Molecular Biology and Biotechnology-Biomedical Research, Foundation for Research and Technology, 45110 Ioannina and the Department of Medicine, Laboratory of Biological Chemistry, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece
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Ben Halima S, Mishra S, Raja KMP, Willem M, Baici A, Simons K, Brüstle O, Koch P, Haass C, Caflisch A, Rajendran L. Specific Inhibition of β-Secretase Processing of the Alzheimer Disease Amyloid Precursor Protein. Cell Rep 2016; 14:2127-2141. [PMID: 26923602 DOI: 10.1016/j.celrep.2016.01.076] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 11/09/2015] [Accepted: 01/26/2016] [Indexed: 01/18/2023] Open
Abstract
Development of disease-modifying therapeutics is urgently needed for treating Alzheimer disease (AD). AD is characterized by toxic β-amyloid (Aβ) peptides produced by β- and γ-secretase-mediated cleavage of the amyloid precursor protein (APP). β-secretase inhibitors reduce Aβ levels, but mechanism-based side effects arise because they also inhibit β-cleavage of non-amyloid substrates like Neuregulin. We report that β-secretase has a higher affinity for Neuregulin than it does for APP. Kinetic studies demonstrate that the affinities and catalytic efficiencies of β-secretase are higher toward non-amyloid substrates than toward APP. We show that non-amyloid substrates are processed by β-secretase in an endocytosis-independent manner. Exploiting this compartmentalization of substrates, we specifically target the endosomal β-secretase by an endosomally targeted β-secretase inhibitor, which blocked cleavage of APP but not non-amyloid substrates in many cell systems, including induced pluripotent stem cell (iPSC)-derived neurons. β-secretase inhibitors can be designed to specifically inhibit the Alzheimer process, enhancing their potential as AD therapeutics without undesired side effects.
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Affiliation(s)
- Saoussen Ben Halima
- Systems and Cell Biology of Neurodegeneration, Institute of Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland; Graduate Program in Neuroscience, Neuroscience Center Zurich, 8057 Zurich, Switzerland; Graduate Program of the Zurich Center for Integrative Human Physiology, University of Zurich, 8057 Zurich, Switzerland
| | - Sabyashachi Mishra
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland
| | - K Muruga Poopathi Raja
- Department of Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Tamil Nadu 625002, Madurai, India
| | - Michael Willem
- Biomedical Center, Ludwig-Maximilians-University, 81337 Munich, Germany
| | - Antonio Baici
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Kai Simons
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Oliver Brüstle
- Institute of Reconstructive Neurobiology, University of Bonn, 53127 Bonn, Germany; German Center for Neurodegenerative Diseases, 53175 Bonn, Germany; Life & Brain, 53127 Bonn, Germany
| | - Philipp Koch
- Institute of Reconstructive Neurobiology, University of Bonn, 53127 Bonn, Germany
| | - Christian Haass
- Biomedical Center, Ludwig-Maximilians-University, 81337 Munich, Germany; German Center for Neurodegenerative Diseases, 53175 Bonn, Germany; Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Lawrence Rajendran
- Systems and Cell Biology of Neurodegeneration, Institute of Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland; Graduate Program in Neuroscience, Neuroscience Center Zurich, 8057 Zurich, Switzerland; Graduate Program of the Zurich Center for Integrative Human Physiology, University of Zurich, 8057 Zurich, Switzerland.
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Chun YS, Kwon OH, Oh HG, Kim TW, McIntire L, Park MK, Chung S. Threonine 576 residue of amyloid-β precursor protein regulates its trafficking and processing. Biochem Biophys Res Commun 2015; 467:955-60. [DOI: 10.1016/j.bbrc.2015.10.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 10/07/2015] [Indexed: 02/08/2023]
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Tam JHK, Pasternak SH. Imaging the Intracellular Trafficking of APP with Photoactivatable GFP. J Vis Exp 2015:e53153. [PMID: 26555118 DOI: 10.3791/53153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Beta-amyloid (Aβ) is the major constituent of senile plaques found in the brains of Alzheimer's disease patients. Aβ is derived from the sequential cleavage of Amyloid Precursor Protein (APP) by β and γ-secretases. Despite the importance of Aβ to AD pathology, the subcellular localization of these cleavages is not well established. Work in our laboratory and others implicate the endosomal/lysosomal system in APP processing after internalization from the cell surface. However, the intracellular trafficking of APP is relatively understudied. While cell-surface proteins are amendable to many labeling techniques, there are no simple methods for following the trafficking of membrane proteins from the Golgi. To this end, we created APP constructs that were tagged with photo-activatable GFP (paGFP) at the C-terminus. After synthesis, paGFP has low basal fluorescence, but it can be stimulated with 413 nm light to produce a strong, stable green fluorescence. By using the Golgi marker Galactosyl transferase coupled to Cyan Fluorescent Protein (GalT-CFP) as a target, we are able to accurately photoactivate APP in the trans-Golgi network. Photo-activated APP-paGFP can then be followed as it traffics to downstream compartments identified with fluorescently tagged compartment marker proteins for the early endosome (Rab5), the late endosome (Rab9) and the lysosome (LAMP1). Furthermore, using inhibitors to APP processing including chloroquine or the γ-secretase inhibitor L685, 458, we are able to perform pulse-chase experiments to examine the processing of APP in single cells. We find that a large fraction of APP moves rapidly to the lysosome without appearing at the cell surface, and is then cleared from the lysosome by secretase-like cleavages. This technique demonstrates the utility of paGFP for following the trafficking and processing of intracellular proteins from the Golgi to downstream compartments.
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Affiliation(s)
- Joshua H K Tam
- Department of Physiology and Pharmacology, Robarts Research Institute, Western University
| | - Stephen H Pasternak
- Department of Physiology and Pharmacology, Robarts Research Institute, Western University; Department of Clinical Neurological Sciences, Western University;
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Sun X, Chen WD, Wang YD. β-Amyloid: the key peptide in the pathogenesis of Alzheimer's disease. Front Pharmacol 2015; 6:221. [PMID: 26483691 PMCID: PMC4588032 DOI: 10.3389/fphar.2015.00221] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 09/17/2015] [Indexed: 12/20/2022] Open
Abstract
The amyloid β peptide (Aβ) is a critical initiator that triggers the progression of Alzheimer's Disease (AD) via accumulation and aggregation, of which the process may be caused by Aβ overproduction or perturbation clearance. Aβ is generated from amyloid precursor protein through sequential cleavage of β- and γ-secretases while Aβ removal is dependent on the proteolysis and lysosome degradation system. Here, we overviewed the biogenesis and toxicity of Aβ as well as the regulation of Aβ production and clearance. Moreover, we also summarized the animal models correlated with Aβ that are essential in AD research. In addition, we discussed current immunotherapeutic approaches targeting Aβ to give some clues for exploring the more potentially efficient drugs for treatment of AD.
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Affiliation(s)
- Xiaojuan Sun
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University Kaifeng, China
| | - Wei-Dong Chen
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University Kaifeng, China
| | - Yan-Dong Wang
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology Beijing, China
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38
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Trafficking and degradation pathways in pathogenic conversion of prions and prion-like proteins in neurodegenerative diseases. Virus Res 2015; 207:146-54. [DOI: 10.1016/j.virusres.2015.01.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 10/01/2014] [Accepted: 01/22/2015] [Indexed: 11/20/2022]
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Abstract
The small, calcium-sensor protein, calmodulin, is ubiquitously expressed and central to cell function in all cell types. Here the literature linking calmodulin to Alzheimer's disease is reviewed. Several experimentally-verified calmodulin-binding proteins are involved in the formation of amyloid-β plaques including amyloid-β protein precursor, β-secretase, presenilin-1, and ADAM10. Many others possess potential calmodulin-binding domains that remain to be verified. Three calmodulin binding proteins are associated with the formation of neurofibrillary tangles: two kinases (CaMKII, CDK5) and one protein phosphatase (PP2B or calcineurin). Many of the genes recently identified by genome wide association studies and other studies encode proteins that contain putative calmodulin-binding domains but only a couple (e.g., APOE, BIN1) have been experimentally confirmed as calmodulin binding proteins. At least two receptors involved in calcium metabolism and linked to Alzheimer's disease (mAchR; NMDAR) have also been identified as calmodulin-binding proteins. In addition to this, many proteins that are involved in other cellular events intimately associated with Alzheimer's disease including calcium channel function, cholesterol metabolism, neuroinflammation, endocytosis, cell cycle events, and apoptosis have been tentatively or experimentally verified as calmodulin binding proteins. The use of calmodulin as a potential biomarker and as a therapeutic target is discussed.
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Affiliation(s)
- Danton H. O’Day
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Kristeen Eshak
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Michael A. Myre
- Center for Human Genetic Research, Richard B. Simches Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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Knowles EEM, Mathias SR, McKay DR, Sprooten E, Blangero J, Almasy L, Glahn DC. Genome-Wide Analyses of Working-Memory Ability: A Review. Curr Behav Neurosci Rep 2014; 1:224-233. [PMID: 25729637 PMCID: PMC4339023 DOI: 10.1007/s40473-014-0028-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Working memory, a theoretical construct from the field of cognitive psychology, is crucial to everyday life. It refers to the ability to temporarily store and manipulate task-relevant information. The identification of genes for working memory might shed light on the molecular mechanisms of this important cognitive ability and-given the genetic overlap between, for example, schizophrenia risk and working-memory ability-might also reveal important candidate genes for psychiatric illness. A number of genome-wide searches for genes that influence working memory have been conducted in recent years. Interestingly, the results of those searches converge on the mediating role of neuronal excitability in working-memory performance, such that the role of each gene highlighted by genome-wide methods plays a part in ion channel formation and/or dopaminergic signaling in the brain, with either direct or indirect influence on dopamine levels in the prefrontal cortex. This result dovetails with animal models of working memory that highlight the role of dynamic network connectivity, as mediated by dopaminergic signaling, in the dorsolateral prefrontal cortex. Future work, which aims to characterize functional variants influencing working-memory ability, might choose to focus on those genes highlighted in the present review and also those networks in which the genes fall. Confirming gene associations and highlighting functional characterization of those associations might have implications for the understanding of normal variation in working-memory ability and also for the development of drugs for mental illness.
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Affiliation(s)
- E E M Knowles
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Olin Neuropsychiatric Research Center, Institute of Living, Hartford, Hospital, Hartford, CT, USA
| | - S R Mathias
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Olin Neuropsychiatric Research Center, Institute of Living, Hartford, Hospital, Hartford, CT, USA
| | - D R McKay
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Olin Neuropsychiatric Research Center, Institute of Living, Hartford, Hospital, Hartford, CT, USA
| | - E Sprooten
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Olin Neuropsychiatric Research Center, Institute of Living, Hartford, Hospital, Hartford, CT, USA
| | - John Blangero
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Laura Almasy
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - D C Glahn
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Olin Neuropsychiatric Research Center, Institute of Living, Hartford, Hospital, Hartford, CT, USA
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41
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Niederst ED, Reyna SM, Goldstein LSB. Axonal amyloid precursor protein and its fragments undergo somatodendritic endocytosis and processing. Mol Biol Cell 2014; 26:205-17. [PMID: 25392299 PMCID: PMC4294669 DOI: 10.1091/mbc.e14-06-1049] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In mouse and human neurons, axonally secreted amyloid precursor protein (APP) fragments are processed in the cell body before being sorted into the axon in a process that requires endocytosis for the processing, but not axonal delivery, of APP. Deposition of potentially neurotoxic Aβ fragments derived from amyloid precursor protein (APP) at synapses may be a key contributor to Alzheimer's disease. However, the location(s) of proteolytic processing and subsequent secretion of APP fragments from highly compartmentalized, euploid neurons that express APP and processing enzymes at normal levels is not well understood. To probe the behavior of endogenous APP, particularly in human neurons, we developed a system using neurons differentiated from human embryonic stem cells, cultured in microfluidic devices, to enable direct biochemical measurements from axons. Using human or mouse neurons in these devices, we measured levels of Aβ, sAPPα, and sAPPβ secreted solely from axons. We found that a majority of the fragments secreted from axons were processed in the soma, and many were dependent on somatic endocytosis for axonal secretion. We also observed that APP and the β-site APP cleaving enzyme were, for the most part, not dependent on endocytosis for axonal entry. These data establish that axonal entry and secretion of APP and its proteolytic processing products traverse different pathways in the somatodendritic compartment before axonal entry.
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Affiliation(s)
- Emily D Niederst
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Sol M Reyna
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
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Belcavello L, Camporez D, Almeida LD, Morelato RL, Batitucci MCP, de Paula F. Association of MTHFR and PICALM polymorphisms with Alzheimer's disease. Mol Biol Rep 2014; 42:611-6. [PMID: 25359311 DOI: 10.1007/s11033-014-3806-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 10/27/2014] [Indexed: 01/17/2023]
Abstract
Alzheimer's disease (AD) is a complex neurodegenerative disorder and the primary cause of dementia in the elderly and causes a decrease in cognition, functionality, and behaviour. Genetic risk factors play an important role in the pathogenesis of AD. In this case-control study, we aimed to investigate whether single nucleotide polymorphisms in MTHFR (rs1801133), PICALM (3851719), CLU (rs11136000), and CR1 (rs6701713) are associated with AD. Genotype frequencies were evaluated in 82 late-onset AD patients and 161 elderly healthy controls matched by age and gender. We detected a significant association of the MTHFR rs1801133 and PICALM rs3851179 polymorphisms with AD. The results of this study support the hypothesis that several genes are involved in the aetiology of AD.
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Affiliation(s)
- Luciano Belcavello
- Department of Biological Sciences, Human Molecular Genetics Center, Federal University of Espírito Santo, Vitória, ES, Brazil,
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43
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Liu CC, Tsai CW, Deak F, Rogers J, Penuliar M, Sung YM, Maher JN, Fu Y, Li X, Xu H, Estus S, Hoe HS, Fryer JD, Kanekiyo T, Bu G. Deficiency in LRP6-mediated Wnt signaling contributes to synaptic abnormalities and amyloid pathology in Alzheimer's disease. Neuron 2014; 84:63-77. [PMID: 25242217 DOI: 10.1016/j.neuron.2014.08.048] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2014] [Indexed: 11/30/2022]
Abstract
Alzheimer's disease (AD) is an age-related neurological disorder characterized by synaptic loss and dementia. The low-density lipoprotein receptor-related protein 6 (LRP6) is an essential coreceptor for Wnt signaling, and its genetic variants have been linked to AD risk. Here we report that neuronal LRP6-mediated Wnt signaling is critical for synaptic function and cognition. Conditional deletion of Lrp6 gene in mouse forebrain neurons leads to age-dependent deficits in synaptic integrity and memory. Neuronal LRP6 deficiency in an amyloid mouse model also leads to exacerbated amyloid pathology due to increased APP processing to amyloid-β. In humans, LRP6 and Wnt signaling are significantly downregulated in AD brains, likely by a mechanism that depends on amyloid-β. Our results define a critical pathway in which decreased LRP6-mediated Wnt signaling, synaptic dysfunction, and elevated Aβ synergistically accelerate AD progression and suggest that restoring LRP6-mediated Wnt signaling can be explored as a viable strategy for AD therapy.
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Affiliation(s)
- Chia-Chen Liu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Chih-Wei Tsai
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Ferenc Deak
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma HSC, Oklahoma City, OK 73104, USA
| | - Justin Rogers
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Michael Penuliar
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - You Me Sung
- Department of Neuroscience, Georgetown University, Washington, D.C. 20057, USA
| | - James N Maher
- Department of Neuroscience, Georgetown University, Washington, D.C. 20057, USA
| | - Yuan Fu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Xia Li
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Steven Estus
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40506, USA
| | - Hyang-Sook Hoe
- Department of Neuroscience, Georgetown University, Washington, D.C. 20057, USA; Convergence Brain Research Department, Korea Brain Research Institute (KBRI), 425, Jungang-daero, Jung-gu, Daegu, Korea
| | - John D Fryer
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Clinic College of Medicine, Jacksonville, FL 32224, USA
| | - Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Clinic College of Medicine, Jacksonville, FL 32224, USA; Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian, China.
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Van Dooren T, Princen K, De Witte K, Griffioen G. Derailed intraneuronal signalling drives pathogenesis in sporadic and familial Alzheimer's disease. BIOMED RESEARCH INTERNATIONAL 2014; 2014:167024. [PMID: 25243118 PMCID: PMC4160617 DOI: 10.1155/2014/167024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/31/2014] [Accepted: 08/03/2014] [Indexed: 02/01/2023]
Abstract
Although a wide variety of genetic and nongenetic Alzheimer's disease (AD) risk factors have been identified, their role in onset and/or progression of neuronal degeneration remains elusive. Systematic analysis of AD risk factors revealed that perturbations of intraneuronal signalling pathways comprise a common mechanistic denominator in both familial and sporadic AD and that such alterations lead to increases in Aβ oligomers (Aβo) formation and phosphorylation of TAU. Conversely, Aβo and TAU impact intracellular signalling directly. This feature entails binding of Aβo to membrane receptors, whereas TAU functionally interacts with downstream transducers. Accordingly, we postulate a positive feedback mechanism in which AD risk factors or genes trigger perturbations of intraneuronal signalling leading to enhanced Aβo formation and TAU phosphorylation which in turn further derange signalling. Ultimately intraneuronal signalling becomes deregulated to the extent that neuronal function and survival cannot be sustained, whereas the resulting elevated levels of amyloidogenic Aβo and phosphorylated TAU species self-polymerizes into the AD plaques and tangles, respectively.
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45
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Merezhko M, Muggalla P, Nykänen NP, Yan X, Sakha P, Huttunen HJ. Multiplex assay for live-cell monitoring of cellular fates of amyloid-β precursor protein (APP). PLoS One 2014; 9:e98619. [PMID: 24932508 PMCID: PMC4059622 DOI: 10.1371/journal.pone.0098619] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/05/2014] [Indexed: 11/19/2022] Open
Abstract
Amyloid-β precursor protein (APP) plays a central role in pathogenesis of Alzheimer's disease. APP has a short half-life and undergoes complex proteolytic processing that is highly responsive to various stimuli such as changes in cellular lipid or energy homeostasis. Cellular trafficking of APP is controlled by its large protein interactome, including dozens of cytosolic adaptor proteins, and also by interactions with lipids. Currently, cellular regulation of APP is mostly studied based on appearance of APP-derived proteolytic fragments to conditioned media and cellular extracts. Here, we have developed a novel live-cell assay system based on several indirect measures that reflect altered APP trafficking and processing in cells. Protein-fragment complementation assay technology for detection of APP-BACE1 protein-protein interaction forms the core of the new assay. In a multiplex form, the assay can measure four endpoints: total cellular APP level, total secreted sAPP level in media, APP-BACE1 interaction in cells and in exosomes released by the cells. Functional validation of the assay with pharmacological and genetic tools revealed distinct patterns of cellular fates of APP, with immediate mechanistic implications. This new technology will facilitate functional genomics studies of late-onset Alzheimer's disease, drug discovery efforts targeting APP and characterization of the physiological functions of APP and its proteolytic fragments.
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Affiliation(s)
- Maria Merezhko
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | | | | | - Xu Yan
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Prasanna Sakha
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Henri J. Huttunen
- Neuroscience Center, University of Helsinki, Helsinki, Finland
- * E-mail: .
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46
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Malnar M, Hecimovic S, Mattsson N, Zetterberg H. Bidirectional links between Alzheimer's disease and Niemann-Pick type C disease. Neurobiol Dis 2014; 72 Pt A:37-47. [PMID: 24907492 DOI: 10.1016/j.nbd.2014.05.033] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 05/17/2014] [Accepted: 05/27/2014] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease (AD) and Niemann-Pick type C (NPC) disease are progressive neurodegenerative diseases with very different epidemiology and etiology. AD is a common cause of dementia with a complex polyfactorial etiology, including both genetic and environmental risk factors, while NPC is a very rare autosomal recessive disease. However, the diseases share some disease-related molecular pathways, including abnormal cholesterol metabolism, and involvement of amyloid-β (Aβ) and tau pathology. Here we review recent studies on these pathological traits, focusing on studies of Aβ and tau pathology in NPC, and the importance of the NPC1 gene in AD. Further studies of similarities and differences between AD and NPC may be useful to increase the understanding of both these devastating neurological diseases.
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Affiliation(s)
- Martina Malnar
- Division of Molecular Medicine, Rudjer Boskovic Institute, Zagreb, Croatia
| | - Silva Hecimovic
- Division of Molecular Medicine, Rudjer Boskovic Institute, Zagreb, Croatia.
| | - Niklas Mattsson
- Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, Mölndal, Gothenburg, Sweden; Center for Imaging of Neurodegenerative Diseases (CIND), San Francisco VA Medical Center, San Francisco, CA, USA; Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Henrik Zetterberg
- Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, Mölndal, Gothenburg, Sweden; UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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47
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UV irradiation accelerates amyloid precursor protein (APP) processing and disrupts APP axonal transport. J Neurosci 2014; 34:3320-39. [PMID: 24573290 DOI: 10.1523/jneurosci.1503-13.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Overexpression and/or abnormal cleavage of amyloid precursor protein (APP) are linked to Alzheimer's disease (AD) development and progression. However, the molecular mechanisms regulating cellular levels of APP or its processing, and the physiological and pathological consequences of altered processing are not well understood. Here, using mouse and human cells, we found that neuronal damage induced by UV irradiation leads to specific APP, APLP1, and APLP2 decline by accelerating their secretase-dependent processing. Pharmacological inhibition of endosomal/lysosomal activity partially protects UV-induced APP processing implying contribution of the endosomal and/or lysosomal compartments in this process. We found that a biological consequence of UV-induced γ-secretase processing of APP is impairment of APP axonal transport. To probe the functional consequences of impaired APP axonal transport, we isolated and analyzed presumptive APP-containing axonal transport vesicles from mouse cortical synaptosomes using electron microscopy, biochemical, and mass spectrometry analyses. We identified a population of morphologically heterogeneous organelles that contains APP, the secretase machinery, molecular motors, and previously proposed and new residents of APP vesicles. These possible cargoes are enriched in proteins whose dysfunction could contribute to neuronal malfunction and diseases of the nervous system including AD. Together, these results suggest that damage-induced APP processing might impair APP axonal transport, which could result in failure of synaptic maintenance and neuronal dysfunction.
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Schmidt V, Carlo AS, Willnow TE. Apolipoprotein E receptor pathways in Alzheimer disease. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2014; 6:255-70. [PMID: 24604742 DOI: 10.1002/wsbm.1262] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 12/31/2013] [Accepted: 01/03/2014] [Indexed: 11/07/2022]
Abstract
UNLABELLED Alzheimer disease (AD) is the most common neurodegenerative disease affecting millions of patients worldwide. According to the amyloid cascade hypothesis, the formation of neurotoxic oligomers composed of amyloid-β (Aβ) peptides is the main mechanism that causes synaptic dysfunction and, eventually, neuronal cell death in this condition. Intriguingly, apolipoprotein E (apoE), the most important genetic risk factor for sporadic AD, emerges as a key factor that contributes to many aspects of the amyloid cascade including the clearance of Aβ from brain interstitial fluid and the ability of this peptide to form neurotoxic oligomers. Central to the activity of apoE in the healthy and in the diseased brain are apoE receptors that interact with this protein to mediate its multiple cellular and systemic effects. This review describes the molecular interactions that link apoE and its cellular receptors with neuronal viability and function, and how defects in these pathways in the brain promote neurodegeneration. For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST The authors have declared no conflicts of interest for this article.
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Affiliation(s)
- Vanessa Schmidt
- Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
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49
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Morel E, Chamoun Z, Lasiecka ZM, Chan RB, Williamson RL, Vetanovetz C, Dall'Armi C, Simoes S, Point Du Jour KS, McCabe BD, Small SA, Di Paolo G. Phosphatidylinositol-3-phosphate regulates sorting and processing of amyloid precursor protein through the endosomal system. Nat Commun 2014; 4:2250. [PMID: 23907271 DOI: 10.1038/ncomms3250] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 07/03/2013] [Indexed: 01/24/2023] Open
Abstract
Defects in endosomal sorting have been implicated in Alzheimer's disease. Endosomal traffic is largely controlled by phosphatidylinositol-3-phosphate, a phosphoinositide synthesized primarily by lipid kinase Vps34. Here we show that phosphatidylinositol-3-phosphate is selectively deficient in brain tissue from humans with Alzheimer's disease and Alzheimer's disease mouse models. Silencing Vps34 causes an enlargement of neuronal endosomes, enhances the amyloidogenic processing of amyloid precursor protein in these organelles and reduces amyloid precursor protein sorting to intraluminal vesicles. This trafficking phenotype is recapitulated by silencing components of the ESCRT (Endosomal Sorting Complex Required for Transport) pathway, including the phosphatidylinositol-3-phosphate effector Hrs and Tsg101. Amyloid precursor protein is ubiquitinated, and interfering with this process by targeted mutagenesis alters sorting of amyloid precursor protein to the intraluminal vesicles of endosomes and enhances amyloid-beta peptide generation. In addition to establishing phosphatidylinositol-3-phosphate deficiency as a contributing factor in Alzheimer's disease, these results clarify the mechanisms of amyloid precursor protein trafficking through the endosomal system in normal and pathological states.
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Affiliation(s)
- Etienne Morel
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
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50
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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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