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Khandekar N, Lie KH, Sachdev PS, Sidhu KS. Amyloid precursor proteins, neural differentiation of pluripotent stem cells and its relevance to Alzheimer's disease. Stem Cells Dev 2012; 21:997-1006. [PMID: 22122714 DOI: 10.1089/scd.2011.0564] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Alzheimer's disease (AD) is a leading cause of age-related dementia that is characterized by an extensive loss of neurons and synaptic transmission. The pathological hallmarks of AD are neurofibrillary tangles and deposition of β-amyloid (Aβ) plaques. Previous research has investigated how Aβ fragments disrupt synaptic mechanisms in the vulnerable regions of the brain. There is a tremendous potential for stem cell technology to extend upon this research, not only in terms of developing therapeutic applications, but also in modeling AD. Indeed, the advent of induced pluripotent stem cell technology has opened up exciting new avenues for generating patient and disease-specific cell lines from somatic cells that may be used to model AD. Amyloid precursor protein (APP) is a key protein in neuronal development and this article reviews the role of APP in AD. Stem cell technology offers the opportunity to make use of APP in the directed differentiation of induced pluripotent stem cells into functional neurons, a process that may help generate a model of AD and thereby facilitate an understanding of the mechanisms underlying this disease.
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Affiliation(s)
- Neeta Khandekar
- Faculty of Medicine, School of Psychiatry, University of New South Wales, Sydney, NSW, Australia.
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202
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Woo JA, Roh SE, Lakshmana MK, Kang DE. Pivotal role of RanBP9 in integrin-dependent focal adhesion signaling and assembly. FASEB J 2012; 26:1672-81. [PMID: 22223749 DOI: 10.1096/fj.11-194423] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Accumulation of the amyloid β (Aβ) peptide derived from the amyloid precursor protein (APP) plays a central role in the pathogenesis of Alzheimer's disease (AD). We previously reported that the scaffolding protein RanBP9 is markedly increased in AD brains and promotes Aβ generation by scaffolding APP/BACE1/LRP complexes together and accelerating APP endocytosis. Because APP, LRP, and RanBP9 all physically interact with β-integrins, we investigated whether RanBP9 alters integrin-dependent cell adhesion and focal adhesion signaling. Here, we show that RanBP9 overexpression dramatically disrupts integrin-dependent cell attachment and spreading in NIH3T3 and hippocampus-derived HT22 cells, concomitant with strongly decreased Pyk2/paxillin signaling and talin/vinculin localization in focal adhesion complexes. Conversely, RanBP9 knockdown robustly promotes cell attachment, spreading, and focal adhesion signaling and assembly. Cell surface biotinylation and endocytosis assays reveal that RanBP9 overexpression and RanBP9 siRNA potently reduces and increases surface β1-integrin and LRP by accelerating and inhibiting their endocytosis, respectively. Primary hippocampal neurons derived from RanBP9-transgenic mice also demonstrate severely reduced levels of surface β1-integrin, LRP, and APP, as well as neurite arborization. Therefore, these data indicate that RanBP9 simultaneously inhibits cell-adhesive processes and enhances Aβ generation by accelerating APP, LRP, and β1-integrin endocytosis.
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Affiliation(s)
- Jung A Woo
- World Class University-Neurocytomics Program, Seoul National University College of Medicine, Seoul, Korea
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203
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So PP, Zeldich E, Seyb KI, Huang MM, Concannon JB, King GD, Chen CD, Cuny GD, Glicksman MA, Abraham CR. Lowering of amyloid beta peptide production with a small molecule inhibitor of amyloid-β precursor protein dimerization. AMERICAN JOURNAL OF NEURODEGENERATIVE DISEASE 2012; 1:75-87. [PMID: 22822474 PMCID: PMC3560454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 04/22/2012] [Indexed: 06/01/2023]
Abstract
The amyloid β precursor protein (APP) is a single-pass transmembrane glycoprotein that is ubiquitously expressed in many cell types, including neurons. Amyloidogenic processing of APP by β- and γ-secretases leads to the production of amyloid-β (Aβ) peptides that can oligomerize and aggregate into amyloid plaques, a characteristic hallmark of Alzheimer's disease (AD) brains. Multiple reports suggest that dimerization of APP may play a role in Aβ production; however, it is not yet clear whether APP dimers increase or decrease Aβ and the mechanism is not fully understood. To better understand the relationship between APP dimerization and production of Aβ, a high throughput screen for small molecule modulators of APP dimerization was conducted using APP-Firefly luciferase enzyme complementation to detect APP dimerization. Selected modulators identified from a compound library of 77,440 compounds were tested for their effects on Aβ generation. Two molecules that inhibited APP dimerization produced a reduction in Aβ levels as measured by ELISA. The inhibitors did not change sAPPα or γ-CTF levels, but lowered sAPPβ levels, suggesting that blocking the dimerization is preventing the cleavage by β-secretase in the amyloidogenic processing of APP. To our knowledge, this is the first High Throughput Screen (HTS) effort to identify small molecule modulators of APP dimerization. Inhibition of APP dimerization has previously been suggested as a therapeutic target in AD. The findings reported here further support that modulation of APP dimerization may be a viable means of reducing the production of Aβ.
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Affiliation(s)
- Pauline Pl So
- Department of Medicine Graduate Program in Molecular Medicine, Boston University School of Medicine, Boston, MA, USA
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204
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Sun MK, Alkon DL. Activation of protein kinase C isozymes for the treatment of dementias. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2012; 64:273-302. [PMID: 22840750 DOI: 10.1016/b978-0-12-394816-8.00008-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Memories are much more easily impaired than improved. Dementias, a lasting impairment of memory function, occur in a variety of cognitive disorders and become more clinically dominant as the population ages. Protein kinase C is one of the "cognitive kinases," and plays an essential role in both memory acquisition and maintenance. Deficits in protein kinase C (PKC) signal cascades in neurons represent one of the earliest changes in the brains of patients with Alzheimer's disease (AD) and other types of memory impairment, including those related to cerebral ischemia and ischemic stroke. Inhibition or impairment of PKC activity results in compromised learning and memory, whereas an appropriate activation of certain PKC isozymes leads to an enhancement of learning and memory and/or antidementic effects. In preclinical studies, PKC activators have been shown to increase the expression and activity of PKC isozymes, thereby restoring PKC signaling and downstream activity, including stimulation of neurotrophic activity, synaptic/structural remodeling, and synaptogenesis in the hippocampus and related cortical areas. PKC activators also reduce the accumulation of neurotoxic amyloid and tau protein hyperphosphorylation and support anti-apoptotic processes in the brain. These observations strongly suggest that PKC pharmacology may represent an attractive area for the development of effective cognition-enhancing therapeutics for the treatment of dementias.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
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205
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Chasseigneaux S, Allinquant B. Functions of Aβ, sAPPα and sAPPβ : similarities and differences. J Neurochem 2011; 120 Suppl 1:99-108. [PMID: 22150401 DOI: 10.1111/j.1471-4159.2011.07584.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Amyloid peptide (Aβ) is derived from the cleavage of amyloid precursor protein (APP), which also generates the soluble peptide APPβ (sAPPβ). An antagonist and major APP metabolic pathway involves cleavage by alpha secretase, which releases sAPPα. Although soluble Aβ oligomers are neurotoxic, Aβ monomers share similar properties with sAPPα. These include neurotrophic and neuroprotective effects, as well as stimulation of neural-progenitor proliferation. The properties of Aβ monomers and the neurotrophic capacity of sAPPβ to stimulate axonal outgrowth suggest that Aβ production is not deleterious per se. Consequently, therapeutic strategies for Alzheimer's disease that are targeted at Aβ-cleaving enzymes should modulate rather than inhibit Aβ generation. These strategies should focus on the factors that induce the conversion of Aβ monomers into toxic soluble oligomers. Another interesting therapeutic approach is to focus on the mechanisms of the different properties of sAPPα. Indeed, increasing sAPPα levels could shift proliferating cells towards tumorigenesis. In contrast to its neuroprotective effects, sAPPα is also able to activate microglia, leading to neurotoxicity. Understanding the mechanisms that underlie the different properties of sAPPα could therefore lead to the development of therapeutic strategies against Alzheimer's disease, which could be curative as well as preventive.
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Affiliation(s)
- Stéphanie Chasseigneaux
- INSERM UMR 894, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| | - Bernadette Allinquant
- INSERM UMR 894, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
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206
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α2-chimaerin controls neuronal migration and functioning of the cerebral cortex through CRMP-2. Nat Neurosci 2011; 15:39-47. [PMID: 22138645 DOI: 10.1038/nn.2972] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 10/03/2011] [Indexed: 11/08/2022]
Abstract
Disrupted cortical neuronal migration is associated with epileptic seizures and developmental delay. However, the molecular mechanism by which disruptions of early cortical development result in neurological symptoms is poorly understood. Here we report α2-chimaerin as a key regulator of cortical neuronal migration and function. In utero suppression of α2-chimaerin arrested neuronal migration at the multipolar stage, leading to accumulation of ectopic neurons in the subcortical region. Mice with such migration defects showed an imbalance between excitation and inhibition in local cortical circuitry and greater susceptibility to convulsant-induced seizures. We further show that α2-chimaerin regulates bipolar transition and neuronal migration through modulating the activity of CRMP-2, a microtubule-associated protein. These findings establish a new α2-chimaerin-dependent mechanism underlying neuronal migration and proper functioning of the cerebral cortex and provide insights into the pathogenesis of seizure-related neurodevelopmental disorders.
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207
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Zhang H, Ma Q, Zhang YW, Xu H. Proteolytic processing of Alzheimer's β-amyloid precursor protein. J Neurochem 2011; 120 Suppl 1:9-21. [PMID: 22122372 DOI: 10.1111/j.1471-4159.2011.07519.x] [Citation(s) in RCA: 233] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
β-Amyloid precursor protein (APP) is a critical factor in the pathogenesis of Alzheimer's disease (AD). APP undergoes post-translational proteolysis/processing to generate the hydrophobic β-amyloid (Aβ) peptides. Deposition of Aβ in the brain, forming oligomeric Aβ and plaques, is identified as one of the key pathological hallmarks of AD. The processing of APP to generate Aβ is executed by β- and γ-secretase and is highly regulated. Aβ toxicity can lead to synaptic dysfunction, neuronal cell death, impaired learning/memory and abnormal behaviors in AD models in vitro and in vivo. Aside from Aβ, proteolytic cleavages of APP can also give rise to the APP intracellular domain, reportedly involved in multiple types of cellular events such as gene transcription and apoptotic cell death. In addition to amyloidogenic processing, APP can also be cleaved by α-secretase to form a soluble or secreted APP ectodomain (sAPP-α) that has been shown to be mostly neuro-protective. In this review, we describe the mechanisms involved in APP metabolism and the likely functions of its various proteolytic products to give a better understanding of the patho/physiological functions of APP.
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Affiliation(s)
- Han Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China.,Neurodegenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
| | - Qilin Ma
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, China
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China.,Neurodegenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
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208
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Ben Khalifa N, Tyteca D, Marinangeli C, Depuydt M, Collet JF, Courtoy PJ, Renauld JC, Constantinescu S, Octave JN, Kienlen-Campard P. Structural features of the KPI domain control APP dimerization, trafficking, and processing. FASEB J 2011; 26:855-67. [PMID: 22085646 DOI: 10.1096/fj.11-190207] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The two major isoforms of human APP, APP695 and APP751, differ by the presence of a Kunitz-type protease inhibitor (KPI) domain in the extracellular region. APP processing and function is thought to be regulated by homodimerization. We used bimolecular fluorescence complementation (BiFC) to study dimerization of different APP isoforms and mutants. APP751 was found to form significantly more homodimers than APP695. Mutation of dimerization motifs in the TM domain did not affect fluorescence complementation, but native folding of KPI is critical for APP751 homodimerization. APP751 and APP695 dimers were mostly localized at steady state in the Golgi region, suggesting that most of the APP751 and 695 dimers are in the secretory pathway. Mutation of the KPI led to the retention of the APP homodimers in the endoplasmic reticulum. We finally showed that APP751 is more efficiently processed through the nonamyloidogenic pathway than APP695. These findings provide new insight on the particular role of KPI domain in APP dimerization. The correlation observed between dimerization, subcellular localization, and processing suggests that dimerization acts as an efficient regulator of APP trafficking in the secretory compartments that has major consequences on its processing.
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Affiliation(s)
- Naouel Ben Khalifa
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
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209
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Kolk SM, de Mooij-Malsen AJ, Martens GJM. Spatiotemporal Molecular Approach of in utero Electroporation to Functionally Decipher Endophenotypes in Neurodevelopmental Disorders. Front Mol Neurosci 2011; 4:37. [PMID: 22065947 PMCID: PMC3206543 DOI: 10.3389/fnmol.2011.00037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 10/11/2011] [Indexed: 11/21/2022] Open
Abstract
We have only just begun to decipher the complexity of our brain, including its maturation. Correct brain development and communication among brain areas are crucial for proper cognitive behavior. Brain area-specific genes expressed within a particular time window direct neurodevelopmental events such as proliferation, migration, axon guidance, dendritic arborization, and synaptogenesis. These genes can pose as susceptibility factors in neurodevelopmental disorders eventually resulting in area-specific cognitive deficits. Therefore, in utero electroporation (IUE)-mediated gene transfer can aid in creating valuable animal models in which the regionality and time of expression can be restricted for the targeted gene(s). Moreover, through the use of cell-type-specific molecular constructs, expression can be altered in a particular neuronal subset within a distinct area such that we are now able to causally link the function of that gene in that brain region to the etiology of the disorder. Thus, IUE-mediated gene transfer is an attractive molecular technique to spatiotemporally address the developmental aspects of gene function in relation to neurodevelopmental disorder-associated endophenotypes.
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Affiliation(s)
- Sharon Margriet Kolk
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition, and Behaviour, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Nijmegen, Netherlands
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210
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Abstract
Alzheimer's disease (AD), the leading cause of dementia worldwide, is characterized by the accumulation of the β-amyloid peptide (Aβ) within the brain along with hyperphosphorylated and cleaved forms of the microtubule-associated protein tau. Genetic, biochemical, and behavioral research suggest that physiologic generation of the neurotoxic Aβ peptide from sequential amyloid precursor protein (APP) proteolysis is the crucial step in the development of AD. APP is a single-pass transmembrane protein expressed at high levels in the brain and metabolized in a rapid and highly complex fashion by a series of sequential proteases, including the intramembranous γ-secretase complex, which also process other key regulatory molecules. Why Aβ accumulates in the brains of elderly individuals is unclear but could relate to changes in APP metabolism or Aβ elimination. Lessons learned from biochemical and genetic studies of APP processing will be crucial to the development of therapeutic targets to treat AD.
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211
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Hartmann T, Prinetti A. Going the wrong road: Fyn and targeting of amyloid precursor protein to lipid rafts. J Neurochem 2011; 118:677-9. [PMID: 21689102 DOI: 10.1111/j.1471-4159.2011.07353.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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212
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Aydin D, Weyer SW, Müller UC. Functions of the APP gene family in the nervous system: insights from mouse models. Exp Brain Res 2011; 217:423-34. [PMID: 21931985 DOI: 10.1007/s00221-011-2861-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 08/30/2011] [Indexed: 06/16/2024]
Abstract
The amyloid precursor protein (APP) plays a key role in the pathogenesis of Alzheimer's disease (AD), as proteolytical cleavage of APP gives rise to the β-amyloid peptide which is deposited in the brains of Alzheimer patients. During the past years, intense research efforts have been directed at elucidating the physiological function(s) of APP and the question of whether a perturbation of these functions contributes to AD pathogenesis. Indeed, a growing body of evidence has accumulated supporting a role of APP and the two closely related homologues APLP1 and APLP2 in various aspects of nervous system development and function, in particular, for synapse formation and function. This review summarizes recent insights into the in vivo role of the APP gene family from mice lacking individual or combinations of APP family members, with particular emphasis on recently generated knockin mice to examine the in vivo relevance of distinct functional domains.
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Affiliation(s)
- Dorothee Aydin
- Department of Bioinformatics and Functional Genomics, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
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213
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ADP ribosylation factor 6 (ARF6) controls amyloid precursor protein (APP) processing by mediating the endosomal sorting of BACE1. Proc Natl Acad Sci U S A 2011; 108:E559-68. [PMID: 21825135 DOI: 10.1073/pnas.1100745108] [Citation(s) in RCA: 189] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Amyloid β (Aβ) peptides, the primary constituents of senile plaques and a hallmark in Alzheimer's disease pathology, are generated through the sequential cleavage of amyloid precursor protein (APP) by β-site APP cleaving enzyme 1 (BACE1) and γ-secretase. The early endosome is thought to represent a major compartment for APP processing; however, the mechanisms of how BACE1 encounters APP are largely unknown. In contrast to APP internalization, which is clathrin-dependent, we demonstrate that BACE1 is sorted to early endosomes via a route controlled by the small GTPase ADP ribosylation factor 6 (ARF6). Altering ARF6 levels or its activity affects endosomal sorting of BACE1, and consequently results in altered APP processing and Aβ production. Furthermore, sorting of newly internalized BACE1 from ARF6-positive towards RAB GTPase 5 (RAB5)-positive early endosomes depends on its carboxyterminal short acidic cluster-dileucine motif. This ARF6-mediated sorting of BACE1 is confined to the somatodendritic compartment of polarized neurons in agreement with Aβ peptides being primarily secreted from here. These results demonstrate a spatial separation between APP and BACE1 during surface-to-endosome transport, suggesting subcellular trafficking as a regulatory mechanism for this proteolytic processing step. It thereby provides a novel avenue to interfere with Aβ production through a selective modulation of the distinct endosomal transport routes used by BACE1 or APP.
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214
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Jefferson T, Čaušević M, auf dem Keller U, Schilling O, Isbert S, Geyer R, Maier W, Tschickardt S, Jumpertz T, Weggen S, Bond JS, Overall CM, Pietrzik CU, Becker-Pauly C. Metalloprotease meprin beta generates nontoxic N-terminal amyloid precursor protein fragments in vivo. J Biol Chem 2011; 286:27741-50. [PMID: 21646356 PMCID: PMC3149364 DOI: 10.1074/jbc.m111.252718] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 06/02/2011] [Indexed: 01/07/2023] Open
Abstract
Identification of physiologically relevant substrates is still the most challenging part in protease research for understanding the biological activity of these enzymes. The zinc-dependent metalloprotease meprin β is known to be expressed in many tissues with functions in health and disease. Here, we demonstrate unique interactions between meprin β and the amyloid precursor protein (APP). Although APP is intensively studied as a ubiquitously expressed cell surface protein, which is involved in Alzheimer disease, its precise physiological role and relevance remain elusive. Based on a novel proteomics technique termed terminal amine isotopic labeling of substrates (TAILS), APP was identified as a substrate for meprin β. Processing of APP by meprin β was subsequently validated using in vitro and in vivo approaches. N-terminal APP fragments of about 11 and 20 kDa were found in human and mouse brain lysates but not in meprin β(-/-) mouse brain lysates. Although these APP fragments were in the range of those responsible for caspase-induced neurodegeneration, we did not detect cytotoxicity to primary neurons treated by these fragments. Our data demonstrate that meprin β is a physiologically relevant enzyme in APP processing.
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Affiliation(s)
- Tamara Jefferson
- From Cell and Matrix Biology, Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Mirsada Čaušević
- the Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Ulrich auf dem Keller
- the Institute of Cell Biology, Swiss Federal Institute of Technology Zurich, ETH Hoenggerberg, HPM D24, CH-8093 Zurich, Switzerland
| | - Oliver Schilling
- the Institute of Molecular Medicine and Cell Research, University of Freiburg, Stefan-Meier-Strasse 17, D-79104 Freiburg, Germany
| | - Simone Isbert
- the Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Rebecca Geyer
- From Cell and Matrix Biology, Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Wladislaw Maier
- the Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Sabrina Tschickardt
- the Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Thorsten Jumpertz
- the Department of Neuropathology, Heinrich-Heine-University, 40225 Duesseldorf, Germany
| | - Sascha Weggen
- the Department of Neuropathology, Heinrich-Heine-University, 40225 Duesseldorf, Germany
| | - Judith S. Bond
- the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, and
| | - Christopher M. Overall
- the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, and
| | - Claus U. Pietrzik
- the Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, 55128 Mainz, Germany
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215
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Secreted human amyloid precursor protein binds semaphorin 3a and prevents semaphorin-induced growth cone collapse. PLoS One 2011; 6:e22857. [PMID: 21829538 PMCID: PMC3146505 DOI: 10.1371/journal.pone.0022857] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 06/29/2011] [Indexed: 12/04/2022] Open
Abstract
The amyloid precursor protein (APP) is well known for giving rise to the amyloid-β peptide and for its role in Alzheimer's disease. Much less is known, however, on the physiological roles of APP in the development and plasticity of the central nervous system. We have used phage display of a peptide library to identify high-affinity ligands of purified recombinant human sAPPα695 (the soluble, secreted ectodomain from the main neuronal APP isoform). Two peptides thus selected exhibited significant homologies with the conserved extracellular domain of several members of the semaphorin (Sema) family of axon guidance proteins. We show that sAPPα695 binds both purified recombinant Sema3A and Sema3A secreted by transfected HEK293 cells. Interestingly, sAPPα695 inhibited the collapse of embryonic chicken (Gallus gallus domesticus) dorsal root ganglia growth cones promoted by Sema3A (Kd≤8·10−9 M). Two Sema3A-derived peptides homologous to the peptides isolated by phage display blocked sAPPα binding and its inhibitory action on Sema3A function. These two peptides are comprised within a domain previously shown to be involved in binding of Sema3A to its cellular receptor, suggesting a competitive mechanism by which sAPPα modulates the biological action of semaphorins.
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216
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Abstract
The amyloid precursor protein (APP) has been under intensive study in recent years, mainly due to its critical role in the pathogenesis of Alzheimer's disease (AD). β-Amyloid (Aβ) peptides generated from APP proteolytic cleavage can aggregate, leading to plaque formation in human AD brains. Point mutations of APP affecting Aβ production are found to be causal for hereditary early onset familial AD. It is very likely that elucidating the physiological properties of APP will greatly facilitate the understanding of its role in AD pathogenesis. A number of APP loss- and gain-of-function models have been established in model organisms including Caenorhabditis elegans, Drosophila, zebrafish and mouse. These in vivo models provide us valuable insights into APP physiological functions. In addition, several knock-in mouse models expressing mutant APP at a physiological level are available to allow us to study AD pathogenesis without APP overexpression. This article will review the current physiological and pathophysiological animal models of APP.
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217
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Zhou ZD, Chan CHS, Ma QH, Xu XH, Xiao ZC, Tan EK. The roles of amyloid precursor protein (APP) in neurogenesis: Implications to pathogenesis and therapy of Alzheimer disease. Cell Adh Migr 2011; 5:280-92. [PMID: 21785276 DOI: 10.4161/cam.5.4.16986] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The amyloid-beta (Aβ) peptide is the derivative of amyloid precursor protein (APP) generated through sequential proteolytic processing by β- and γ-secretases. Excessive accumulation of Aβ, the main constituent of amyloid plaques, has been implicated in the etiology of Alzheimer's disease (AD). It was found recently that the impairments of neurogenesis in brain were associated with the pathogenesis of AD. Furthermore recent findings implicated that APP could function to influence proliferation of neural progenitor cells (NPC) and might regulate transcriptional activity of various genes. Studies demonstrated that influence of neurogenesis by APP is conferred differently via its two separate domains, soluble secreted APPs (sAPPs, mainly sAPPα) and APP intracellular domain (AICD). The sAPPα was shown to be neuroprotective and important to neurogenesis, whereas AICD was found to negatively modulate neurogenesis. Furthermore, it was demonstrated recently that microRNA could function to regulate APP expression, APP processing, Aβ accumulation and subsequently influence neurotoxicity and neurogenesis related to APP, which was implicated to AD pathogenesis, especially for sporadic AD. Based on data accumulated, secretase balances were proposed. These secretase balances could influence the downstream balance related to regulation of neurogenesis by AICD and sAPPα as well as balance related to influence of neuron viability by Aβ and sAPPα. Disruption of these secretase balances could be culprits to AD onset.
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218
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Abstract
Over the last three decades, advances in biochemical pathology and human genetics have illuminated one of the most enigmatic subjects in biomedicine--neurodegeneration. Eponymic diseases of the nervous system such as Alzheimer's, Parkinson's, and Huntington's diseases that were long characterized by mechanistic ignorance have yielded striking progress in our understanding of their molecular underpinnings. A central theme in these and related disorders is the concept that certain normally soluble neuronal proteins can misfold and aggregate into oligomers and amyloid fibrils which can confer profound cytotoxicity. Perhaps the foremost example, both in terms of its societal impact and how far knowledge has moved toward the clinic, is that of Alzheimer's disease (AD). Here, we will review the classical protein lesions of the disorder that have provided a road map to etiology and pathogenesis. We will discuss how elucidating the genotype-to-phenotype relationships of familial forms of Alzheimer's disease has highlighted the importance of the misfolding and altered proteostasis of two otherwise soluble proteins, amyloid β-protein and tau, suggesting mechanism-based therapeutic targets that have led to clinical trials.
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Affiliation(s)
- Dennis J Selkoe
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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219
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Selective interaction of amyloid precursor protein with different isoforms of neural cell adhesion molecule. J Mol Neurosci 2011; 46:203-9. [PMID: 21691800 DOI: 10.1007/s12031-011-9578-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 06/08/2011] [Indexed: 10/18/2022]
Abstract
Compare to the thoroughly studied beta-amyloid, the physiological function of amyloid precursor protein (APP) is not well understood. We now had identified neural cell adhesion molecule (NCAM)-140 as a potential interaction partner of APP. Our data indicated that NCAM-140, but not NCAM-180, binds to the conserved central extracellular domain of APP. We also found that the phosphorylation levels of ERK1 and ERK2 were increased when cells were co-transfected with NCAM-140 and APP indicate that the interaction between NCAM-140 and APP may involve the MAPK pathway. These findings demonstrated that NCAM-140 interacts with APP, potentially playing a role in neurite outgrowth and neural development.
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220
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Sokol DK, Maloney B, Long JM, Ray B, Lahiri DK. Autism, Alzheimer disease, and fragile X: APP, FMRP, and mGluR5 are molecular links. Neurology 2011; 76:1344-52. [PMID: 21482951 DOI: 10.1212/wnl.0b013e3182166dc7] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The present review highlights an association between autism, Alzheimer disease (AD), and fragile X syndrome (FXS). We propose a conceptual framework involving the amyloid-β peptide (Aβ), Aβ precursor protein (APP), and fragile X mental retardation protein (FMRP) based on experimental evidence. The anabolic (growth-promoting) effect of the secreted α form of the amyloid-β precursor protein (sAPPα) may contribute to the state of brain overgrowth implicated in autism and FXS. Our previous report demonstrated that higher plasma sAPPα levels associate with more severe symptoms of autism, including aggression. This molecular effect could contribute to intellectual disability due to repression of cell-cell adhesion, promotion of dense, long, thin dendritic spines, and the potential for disorganized brain structure as a result of disrupted neurogenesis and migration. At the molecular level, APP and FMRP are linked via the metabotropic glutamate receptor 5 (mGluR5). Specifically, mGluR5 activation releases FMRP repression of APP mRNA translation and stimulates sAPP secretion. The relatively lower sAPPα level in AD may contribute to AD symptoms that significantly contrast with those of FXS and autism. Low sAPPα and production of insoluble Aβ would favor a degenerative process, with the brain atrophy seen in AD. Treatment with mGluR antagonists may help repress APP mRNA translation and reduce secretion of sAPP in FXS and perhaps autism.
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Affiliation(s)
- D K Sokol
- Department of Neurology, Indiana University School of Medicine, 791 Union Drive, Indianapolis, IN 46202, USA
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221
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Minami SS, Hoe HS, Rebeck GW. Fyn kinase regulates the association between amyloid precursor protein and Dab1 by promoting their localization to detergent-resistant membranes. J Neurochem 2011; 118:879-90. [PMID: 21534960 DOI: 10.1111/j.1471-4159.2011.07296.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The adaptor protein Disabled1 (Dab1) interacts with amyloid precursor protein (APP) and decreases its pathological processing, an effect mediated by Fyn tyrosine kinase. Fyn is highly enriched in lipid rafts, a major site of pathological APP processing. To investigate the role of Fyn in the localization and phosphorylation of APP and Dab1 in lipid rafts, we isolated detergent-resistant membrane (DRM) fractions from wild-type and Fyn knock-out mice. In wild-type mice, all of the Fyn kinase, 17% of total APP, and 33% of total Dab1 were found in DRMs. Nearly all of the tyrosine phosphorylated forms of APP and Dab1 were in DRMs. APP and Dab1 co-precipitated both in and out of DRM fractions, indicating an association that is independent of subcellular localization. Fyn knock-out mice had decreased APP, Dab1, and tyrosine-phosphorylated Dab1 in DRMs but increased co-immunoprecipitation of DRM APP and Dab1. Expression of phosphorylation deficient APP or Dab1 constructs revealed that phosphorylation of APP increases, whereas phosphorylation of Dab1 decreases, the interaction between APP and Dab1. Consistent with these observations, Reelin treatment led to increased Dab1 phosphorylation and decreased association between APP and Dab1. Reelin also caused increased localization of APP and Dab1 to DRMs, an effect that was not seen in Fyn knock-out neurons. These findings suggest that Reelin treatment promotes the localization of APP and Dab1 to DRMs, and affects their phosphorylation by Fyn, thus regulating their interaction.
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Affiliation(s)
- S Sakura Minami
- Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia 20057-1464, USA
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222
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Freude KK, Penjwini M, Davis JL, LaFerla FM, Blurton-Jones M. Soluble amyloid precursor protein induces rapid neural differentiation of human embryonic stem cells. J Biol Chem 2011; 286:24264-74. [PMID: 21606494 PMCID: PMC3129207 DOI: 10.1074/jbc.m111.227421] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Human embryonic stem cells (hESCs) offer tremendous potential for not only treating neurological disorders but also for their ability to serve as vital reagents to model and investigate human disease. To further our understanding of a key protein involved in Alzheimer disease pathogenesis, we stably overexpressed amyloid precursor protein (APP) in hESCs. Remarkably, we found that APP overexpression in hESCs caused a rapid and robust differentiation of pluripotent stem cells toward a neural fate. Despite maintenance in standard hESC media, up to 80% of cells expressed the neural stem cell marker nestin, and 65% exhibited the more mature neural marker β-3 tubulin within just 5 days of passaging. To elucidate the mechanism underlying the effects of APP on neural differentiation, we examined the proteolysis of APP and performed both gain of function and loss of function experiments. Taken together, our results demonstrate that the N-terminal secreted soluble forms of APP (in particular sAPPβ) robustly drive neural differentiation of hESCs. Our findings not only reveal a novel and intriguing role for APP in neural lineage commitment but also identify a straightforward and rapid approach to generate large numbers of neurons from human embryonic stem cells. These novel APP-hESC lines represent a valuable tool to investigate the potential role of APP in development and neurodegeneration and allow for insights into physiological functions of this protein.
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Affiliation(s)
- Kristine K Freude
- Department of Neurobiology and Behavior and Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California 92697, USA
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223
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Bugiani O. Alzheimer’s disease: ageing-related or age-related? New hypotheses from an old debate. Neurol Sci 2011; 32:1241-7. [DOI: 10.1007/s10072-011-0614-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 04/28/2011] [Indexed: 11/28/2022]
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224
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Taniguchi Y, Young-Pearse T, Sawa A, Kamiya A. In utero electroporation as a tool for genetic manipulation in vivo to study psychiatric disorders: from genes to circuits and behaviors. Neuroscientist 2011; 18:169-79. [PMID: 21551077 DOI: 10.1177/1073858411399925] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Many genetic risk factors for major mental disorders have key roles in brain development. Thus, exploring the roles for these genetic factors for brain development at the molecular, cellular, and neuronal circuit level is crucial for discovering how genetic disturbances affect high brain functions, which ultimately lead to disease pathologies. However, it is a tremendously difficult task, given that most mental disorders have genetic complexities in which many genetic risk factors have multiple roles in different cell types and brain regions over a time-course dependent manner. Furthermore, some genetic risk factors are likely to act epistatically in common molecular pathways. For this reason, a technique for spatial and temporal manipulation of multiple genes is necessary for understanding how genetic disturbances contribute to disease etiology. Here, the authors will review the said technique, in utero electroporation, which investigates the molecular disease pathways in rodent models for major mental disorders. This technique is also useful to examine the effect of genetic risks at the behavioral level. Furthermore, the authors will discuss the recent progress of this technology, such as inducible and cell type-specific targeting, as well as nonepisomal genetic manipulation, which provide further availability of this technique for research on major mental disorders.
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Affiliation(s)
- Yu Taniguchi
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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225
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Zheng H, Koo EH. Biology and pathophysiology of the amyloid precursor protein. Mol Neurodegener 2011; 6:27. [PMID: 21527012 PMCID: PMC3098799 DOI: 10.1186/1750-1326-6-27] [Citation(s) in RCA: 221] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 04/28/2011] [Indexed: 01/22/2023] Open
Abstract
The amyloid precursor protein (APP) plays a central role in the pathophysiology of Alzheimer's disease in large part due to the sequential proteolytic cleavages that result in the generation of β-amyloid peptides (Aβ). Not surprisingly, the biological properties of APP have also been the subject of great interest and intense investigations. Since our 2006 review, the body of literature on APP continues to expand, thereby offering further insights into the biochemical, cellular and functional properties of this interesting molecule. Sophisticated mouse models have been created to allow in vivo examination of cell type-specific functions of APP together with the many functional domains. This review provides an overview and update on our current understanding of the pathobiology of APP.
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Affiliation(s)
- Hui Zheng
- Huffington Center on Aging and Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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226
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Franco SJ, Martinez-Garay I, Gil-Sanz C, Harkins-Perry SR, Müller U. Reelin regulates cadherin function via Dab1/Rap1 to control neuronal migration and lamination in the neocortex. Neuron 2011; 69:482-97. [PMID: 21315259 DOI: 10.1016/j.neuron.2011.01.003] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2011] [Indexed: 10/18/2022]
Abstract
Neuronal migration is critical for establishing neocortical cell layers and migration defects can cause neurological and psychiatric diseases. Recent studies show that radially migrating neocortical neurons use glia-dependent and glia-independent modes of migration, but the signaling pathways that control different migration modes and the transitions between them are poorly defined. Here, we show that Dab1, an essential component of the reelin pathway, is required in radially migrating neurons for glia-independent somal translocation, but not for glia-guided locomotion. During migration, Dab1 acts in translocating neurons to stabilize their leading processes in a Rap1-dependent manner. Rap1, in turn, controls cadherin function to regulate somal translocation. Furthermore, cell-autonomous neuronal deficits in somal translocation are sufficient to cause severe neocortical lamination defects. Thus, we define the cellular mechanism of reelin function during radial migration, elucidate the molecular pathway downstream of Dab1 during somal translocation, and establish the importance of glia-independent motility in neocortical development.
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Affiliation(s)
- Santos J Franco
- Dorris Neuroscience Center and Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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227
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Lodato S, Rouaux C, Quast KB, Jantrachotechatchawan C, Studer M, Hensch TK, Arlotta P. Excitatory projection neuron subtypes control the distribution of local inhibitory interneurons in the cerebral cortex. Neuron 2011; 69:763-79. [PMID: 21338885 DOI: 10.1016/j.neuron.2011.01.015] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2010] [Indexed: 01/08/2023]
Abstract
In the mammalian cerebral cortex, the developmental events governing the integration of excitatory projection neurons and inhibitory interneurons into balanced local circuitry are poorly understood. We report that different subtypes of projection neurons uniquely and differentially determine the laminar distribution of cortical interneurons. We find that in Fezf2⁻/⁻ cortex, the exclusive absence of subcerebral projection neurons and their replacement by callosal projection neurons cause distinctly abnormal lamination of interneurons and altered GABAergic inhibition. In addition, experimental generation of either corticofugal neurons or callosal neurons below the cortex is sufficient to recruit cortical interneurons to these ectopic locations. Strikingly, the identity of the projection neurons generated, rather than strictly their birthdate, determines the specific types of interneurons recruited. These data demonstrate that in the neocortex individual populations of projection neurons cell-extrinsically control the laminar fate of interneurons and the assembly of local inhibitory circuitry.
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Affiliation(s)
- Simona Lodato
- Center for Regenerative Medicine and Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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228
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Puzzo D, Privitera L, Fa' M, Staniszewski A, Hashimoto G, Aziz F, Sakurai M, Ribe EM, Troy CM, Mercken M, Jung SS, Palmeri A, Arancio O. Endogenous amyloid-β is necessary for hippocampal synaptic plasticity and memory. Ann Neurol 2011; 69:819-30. [PMID: 21472769 DOI: 10.1002/ana.22313] [Citation(s) in RCA: 221] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 09/10/2010] [Accepted: 10/15/2010] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The goal of this study was to investigate the role of endogenous amyloid-β peptide (Aβ) in healthy brain. METHODS Long-term potentiation (LTP), a type of synaptic plasticity that is thought to be associated with learning and memory, was examined through extracellular field recordings from the CA1 region of hippocampal slices, whereas behavioral techniques were used to assess contextual fear memory and reference memory. Amyloid precursor protein (APP) expression was reduced through small interfering RNA (siRNA) technique. RESULTS We found that both antirodent Aβ antibody and siRNA against murine APP reduced LTP as well as contextual fear memory and reference memory. These effects were rescued by the addition of human Aβ₄₂, suggesting that endogenously produced Aβ is needed for normal LTP and memory. Furthermore, the effect of endogenous Aβ on plasticity and memory was likely due to regulation of transmitter release, activation of α7-containing nicotinic acetylcholine receptors, and Aβ₄₂ production. INTERPRETATION Endogenous Aβ₄₂ is a critical player in synaptic plasticity and memory within the normal central nervous system. This needs to be taken into consideration when designing therapies aiming at reducing Aβ levels to treat Alzheimer disease.
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Affiliation(s)
- Daniela Puzzo
- Department of Pathology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY 10032, USA
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229
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Dinet V, An N, Ciccotosto GD, Bruban J, Maoui A, Bellingham SA, Hill AF, Andersen OM, Nykjaer A, Jonet L, Cappai R, Mascarelli F. APP involvement in retinogenesis of mice. Acta Neuropathol 2011; 121:351-63. [PMID: 20978902 DOI: 10.1007/s00401-010-0762-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 10/11/2010] [Accepted: 10/14/2010] [Indexed: 12/23/2022]
Abstract
Very few studies have examined expression and function of amyloid precursor protein (APP) in the retina. We showed that APP mRNA and protein are expressed according to the different waves of retinal differentiation. Depletion of App led to an absence of amacrine cells, a 50% increase in the number of horizontal cells and alteration of the synapses. The retinas of adult APP(-/-) mice showed only half as many glycinergic amacrine cells as wild-type retinas. We identified Ptf1a, which plays a role in controlling both amacrine and horizontal cell fates, as a downstream effector of APP. The observation of a similar phenotype in sorLA knockout mice, a major regulator of APP processing, suggests that regulation of APP functions via sorLA controls the determination of amacrine and horizontal cell fate. These findings provide novel insights that indicate that APP plays an important role in retinal differentiation.
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Affiliation(s)
- Virginie Dinet
- Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 6, INSERM, 15 rue de l'Ecole de Médecine, Paris, France
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230
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Lu L, Mamiya T, Koseki T, Mouri A, Nabeshima T. Genetic Animal Models of Schizophrenia Related with the Hypothesis of Abnormal Neurodevelopment. Biol Pharm Bull 2011; 34:1358-63. [DOI: 10.1248/bpb.34.1358] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Lingling Lu
- The Academic Frontier Project for Private University, Comparative Cognitive Science Institute, Meijo University
- Department of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Meijo University
| | - Takayoshi Mamiya
- The Academic Frontier Project for Private University, Comparative Cognitive Science Institute, Meijo University
- Department of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Meijo University
- Japanese Drug Organization for Appropriate Use and Research
| | - Takenao Koseki
- The Academic Frontier Project for Private University, Comparative Cognitive Science Institute, Meijo University
- Department of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Meijo University
| | - Akihiro Mouri
- The Academic Frontier Project for Private University, Comparative Cognitive Science Institute, Meijo University
- Department of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Meijo University
- Japanese Drug Organization for Appropriate Use and Research
| | - Toshitaka Nabeshima
- The Academic Frontier Project for Private University, Comparative Cognitive Science Institute, Meijo University
- Department of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Meijo University
- Japanese Drug Organization for Appropriate Use and Research
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231
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Balu DT, Coyle JT. Neuroplasticity signaling pathways linked to the pathophysiology of schizophrenia. Neurosci Biobehav Rev 2011; 35:848-70. [PMID: 20951727 PMCID: PMC3005823 DOI: 10.1016/j.neubiorev.2010.10.005] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 10/06/2010] [Accepted: 10/10/2010] [Indexed: 12/15/2022]
Abstract
Schizophrenia is a severe mental illness that afflicts nearly 1% of the world's population. One of the cardinal pathological features of schizophrenia is perturbation in synaptic connectivity. Although the etiology of schizophrenia is unknown, it appears to be a developmental disorder involving the interaction of a potentially large number of risk genes, with no one gene producing a strong effect except rare, highly penetrant copy number variants. The purpose of this review is to detail how putative schizophrenia risk genes (DISC-1, neuregulin/ErbB4, dysbindin, Akt1, BDNF, and the NMDA receptor) are involved in regulating neuroplasticity and how alterations in their expression may contribute to the disconnectivity observed in schizophrenia. Moreover, this review highlights how many of these risk genes converge to regulate common neurotransmitter systems and signaling pathways. Future studies aimed at elucidating the functions of these risk genes will provide new insights into the pathophysiology of schizophrenia and will likely lead to the nomination of novel therapeutic targets for restoring proper synaptic connectivity in the brain in schizophrenia and related disorders.
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Affiliation(s)
- Darrick T Balu
- Department of Psychiatry, Harvard Medical School, Belmont, MA, USA.
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232
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O'Tuathaigh CMP, Desbonnet L, Moran PM, Waddington JL. Susceptibility genes for schizophrenia: mutant models, endophenotypes and psychobiology. Curr Top Behav Neurosci 2011; 12:209-50. [PMID: 22367925 DOI: 10.1007/7854_2011_194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Schizophrenia is characterised by a multifactorial aetiology that involves genetic liability interacting with epigenetic and environmental factors to increase risk for developing the disorder. A consensus view is that the genetic component involves several common risk alleles of small effect and/or rare but penetrant copy number variations. Furthermore, there is increasing evidence for broader, overlapping genetic-phenotypic relationships in psychosis; for example, the same susceptibility genes also confer risk for bipolar disorder. Phenotypic characterisation of genetic models of candidate risk genes and/or putative pathophysiological processes implicated in schizophrenia, as well as examination of epidemiologically relevant gene × environment interactions in these models, can illuminate molecular and pathobiological mechanisms involved in schizophrenia. The present chapter outlines both the evidence from phenotypic studies in mutant mouse models related to schizophrenia and recently described mutant models addressing such gene × environment interactions. Emphasis is placed on evaluating the extent to which mutant phenotypes recapitulate the totality of the disease phenotype or model selective endophenotypes. We also discuss new developments and trends in relation to the functional genomics of psychosis which might help to inform on the construct validity of mutant models of schizophrenia and highlight methodological challenges in phenotypic evaluation that relate to such models.
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Affiliation(s)
- Colm M P O'Tuathaigh
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin 2, Ireland,
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233
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Barros CS, Franco SJ, Müller U. Extracellular matrix: functions in the nervous system. Cold Spring Harb Perspect Biol 2011; 3:a005108. [PMID: 21123393 DOI: 10.1101/cshperspect.a005108] [Citation(s) in RCA: 260] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An astonishing number of extracellular matrix glycoproteins are expressed in dynamic patterns in the developing and adult nervous system. Neural stem cells, neurons, and glia express receptors that mediate interactions with specific extracellular matrix molecules. Functional studies in vitro and genetic studies in mice have provided evidence that the extracellular matrix affects virtually all aspects of nervous system development and function. Here we will summarize recent findings that have shed light on the specific functions of defined extracellular matrix molecules on such diverse processes as neural stem cell differentiation, neuronal migration, the formation of axonal tracts, and the maturation and function of synapses in the peripheral and central nervous system.
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Affiliation(s)
- Claudia S Barros
- The Scripps Research Institute, Department of Cell Biology, Dorris Neuroscience Center, La Jolla, California 92037, USA
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234
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Abstract
The memory dysfunctions that characterize Alzheimer's disease (AD) are strongly correlated with synapse loss. The amyloid precursor protein (APP) and its cleavage product Aβ play central roles in synapse and memory loss, and thus are strongly implicated in the pathogenesis of AD. Numerous in vitro and transgenic AD mouse model studies have shown that overexpression of APP leads to Aβ accumulation, which causes decreased synaptic activity and dendritic spine density. However, the normal synaptic function of APP itself is not fully understood. Several recent studies have found that full-length APP promotes synaptic activity, synapse formation, and dendritic spine formation. These findings cast APP as a potential key player in learning and memory. It is of interest that the synaptic functions of full-length APP are opposite to the effects associated with pathological Aβ accumulation. In this review, we will summarize the normal functions of APP at synapses and spines along with other known functions of APP, including its role in cell motility, neuronal migration, and neurite outgrowth. These studies shed light on the physiological actions of APP, independent of Aβ effects, and thus lead to a better understanding of the synaptic dysfunctions associated with AD.
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Affiliation(s)
- Hyang-Sook Hoe
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, USA.
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235
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Peterziel H, Sackmann T, Strelau J, Kuhn PH, Lichtenthaler SF, Marom K, Klar A, Unsicker K. F-spondin regulates neuronal survival through activation of disabled-1 in the chicken ciliary ganglion. Mol Cell Neurosci 2010; 46:483-97. [PMID: 21145970 DOI: 10.1016/j.mcn.2010.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 11/19/2010] [Accepted: 12/02/2010] [Indexed: 01/06/2023] Open
Abstract
The extracellular membrane-associated protein F-spondin has been implicated in cell-matrix and cell-cell adhesion and plays an important role in axonal pathfinding. We report here that F-spondin is expressed in non-neuronal cells in the embryonic chicken ciliary ganglion (CG) and robustly promotes survival of cultured CG neurons. Using deletion constructs of F-spondin we found that the amino-terminal Reelin/Spondin domain cooperates with thrombospondin type 1 repeat (TSR) 6, a functional TGFβ-activation domain. In ovo treatment with blocking antibodies raised against the Reelin/Spondin domain or the TSR-domains caused increased apoptosis of CG neurons during the phase of programmed cell death and loss of about 30% of the neurons compared to controls. The Reelin/Spondin domain receptor - APP and its downstream signalling molecule disabled-1 are expressed in CG neurons. F-spondin induced rapid phosphorylation of disabled-1. Moreover, both blocking the central APP domain and interference with disabled-1 signalling disrupted the survival promoting effect of F-spondin. Taken together, our data suggest that F-spondin can promote neuron survival by a mechanism involving the Reelin/Spondin and the TSR domains.
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Affiliation(s)
- H Peterziel
- Neuroanatomy & Interdisciplinary Center for Neurosiences (IZN), University of Heidelberg, Heidelberg, Germany.
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236
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Ruberti F, Barbato C, Cogoni C. Post-transcriptional regulation of amyloid precursor protein by microRNAs and RNA binding proteins. Commun Integr Biol 2010; 3:499-503. [PMID: 21331224 DOI: 10.4161/cib.3.6.13172] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Accepted: 07/27/2010] [Indexed: 11/19/2022] Open
Abstract
Amyloid Precursor Protein (APP) and its proteolytic product amyloid beta (Aβ) are critical in the pathogenesis of Alzheimer's Disease (AD). APP gene duplication and transcriptional upregulation are linked to AD. In addition, normal levels of APP appear to be required for some physiological functions in the developing brain. Several studies in mammalian cell lines and primary neuron cultures indicate that RNA binding proteins and microRNAs interacting with regulatory regions of the APP mRNA modulate expression of APP post-transcriptionally. However, when the various mechanisms of APP post-transcriptional regulation are recruited and which of them are acting in a synergistic fashion to balance APP protein levels, is unclear. Recent studies suggest that further investigation of the molecules and pathways involved in APP post-transcriptional regulation are warranted.
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Affiliation(s)
- Francesca Ruberti
- INMM-CNR Istituto di Neurobiologia e Medicina Molecolare; IRCSS; Fondazione Santa Lucia
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237
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De Vry J, Martínez-Martínez P, Losen M, Temel Y, Steckler T, Steinbusch HWM, De Baets MH, Prickaerts J. In vivo electroporation of the central nervous system: a non-viral approach for targeted gene delivery. Prog Neurobiol 2010; 92:227-44. [PMID: 20937354 DOI: 10.1016/j.pneurobio.2010.10.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 09/24/2010] [Accepted: 10/01/2010] [Indexed: 01/11/2023]
Abstract
Electroporation is a widely used technique for enhancing the efficiency of DNA delivery into cells. Application of electric pulses after local injection of DNA temporarily opens cell membranes and facilitates DNA uptake. Delivery of plasmid DNA by electroporation to alter gene expression in tissue has also been explored in vivo. This approach may constitute an alternative to viral gene transfer, or to transgenic or knock-out animals. Among the most frequently electroporated target tissues are skin, muscle, eye, and tumors. Moreover, different regions in the central nervous system (CNS), including the developing neural tube and the spinal cord, as well as prenatal and postnatal brain have been successfully electroporated. Here, we present a comprehensive review of the literature describing electroporation of the CNS with a focus on the adult brain. In addition, the mechanism of electroporation, different ways of delivering the electric pulses, and the risk of damaging the target tissue are highlighted. Electroporation has been successfully used in humans to enhance gene transfer in vaccination or cancer therapy with several clinical trials currently ongoing. Improving the knowledge about in vivo electroporation will pave the way for electroporation-enhanced gene therapy to treat brain carcinomas, as well as CNS disorders such as Alzheimer's disease, Parkinson's disease, and depression.
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Affiliation(s)
- Jochen De Vry
- Department of Psychiatry & Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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238
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Förster E, Bock HH, Herz J, Chai X, Frotscher M, Zhao S. Emerging topics in Reelin function. Eur J Neurosci 2010; 31:1511-8. [PMID: 20525064 DOI: 10.1111/j.1460-9568.2010.07222.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Reelin signalling in the early developing cortex regulates radial migration of cortical neurons. Later in development, Reelin promotes maturation of dendrites and dendritic spines. Finally, in the mature brain, it is involved in modulating synaptic function. In recent years, efforts to identify downstream signalling events induced by binding of Reelin to lipoprotein receptors led to the characterization of novel components of the Reelin signalling cascade. In the present review, we first address distinct functions of the Reelin receptors Apoer2 and Vldlr in cortical layer formation, followed by a discussion on the recently identified downstream effector molecule n-cofilin, involved in regulating actin cytoskeletal dynamics required for coordinated neuronal migration. Next, we discuss possible functions of the recently identified Reelin-Notch signalling crosstalk, and new aspects of the role of Reelin in the formation of the dentate radial glial scaffold. Finally, progress in characterizing the function of Reelin in modulating synaptic function in the adult brain is summarized. The present review has been inspired by a session entitled 'Functions of Reelin in the developing and adult hippocampus', held at the Spring Hippocampal Research Conference in Verona/Italy, June 2009.
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Affiliation(s)
- Eckart Förster
- Institut für Anatomie I: Zelluläre Neurobiologie, Hamburg, Germany.
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239
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Rice H, Suth S, Cavanaugh W, Bai J, Young-Pearse TL. In utero electroporation followed by primary neuronal culture for studying gene function in subset of cortical neurons. J Vis Exp 2010:2103. [PMID: 20972409 DOI: 10.3791/2103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In vitro study of primary neuronal cultures allows for quantitative analyses of neurite outgrowth. In order to study how genetic alterations affect neuronal process outgrowth, shRNA or cDNA constructs can be introduced into primary neurons via chemical transfection or viral transduction. However, with primary cortical cells, a heterogeneous pool of cell types (glutamatergic neurons from different layers, inhibitory neurons, glial cells) are transfected using these methods. The use of in utero electroporation to introduce DNA constructs in the embryonic rodent cortex allows for certain subsets of cells to be targeted: while electroporation of early embryonic cortex targets deep layers of the cortex, electroporation at late embryonic timepoints targets more superficial layers. Further, differential placement of electrodes across the heads of individual embryos results in the targeting of dorsal-medial versus ventral-lateral regions of the cortex. Following electroporation, transfected cells can be dissected out, dissociated, and plated in vitro for quantitative analysis of neurite outgrowth. Here, we provide a step-by-step method to quantitatively measure neuronal process outgrowth in subsets of cortical cells. The basic protocol for in utero electroporation has been described in detail in two other JoVE articles from the Kriegstein lab. We will provide an overview of our protocol for in utero electroporation, focusing on the most important details, followed by a description of our protocol that applies in utero electroporation to the study of gene function in neuronal process outgrowth.
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Affiliation(s)
- Heather Rice
- Center for Neurologic Diseases, Harvard Medical School
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240
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Ben-Ari Y, Spitzer NC. Phenotypic checkpoints regulate neuronal development. Trends Neurosci 2010; 33:485-92. [PMID: 20864191 DOI: 10.1016/j.tins.2010.08.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 08/22/2010] [Accepted: 08/22/2010] [Indexed: 12/22/2022]
Abstract
Nervous system development proceeds by sequential gene expression mediated by cascades of transcription factors in parallel with sequences of patterned network activity driven by receptors and ion channels. These sequences are cell type- and developmental stage-dependent and modulated by paracrine actions of substances released by neurons and glia. How and to what extent these sequences interact to enable neuronal network development is not understood. Recent evidence demonstrates that CNS development requires intermediate stages of differentiation providing functional feedback that influences gene expression. We suggest that embryonic neuronal functions constitute a series of phenotypic checkpoint signatures; neurons failing to express these functions are delayed or developmentally arrested. Such checkpoints are likely to be a general feature of neuronal development and constitute presymptomatic signatures of neurological disorders when they go awry.
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Affiliation(s)
- Yehezkel Ben-Ari
- Institut de Neurobiologie de la Méditerranée (INMED), Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 901, Parc Scientifique de Luminy, Marseille CEDEX 09, France.
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241
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Serb JM, Orr MC, West Greenlee MH. Using evolutionary conserved modules in gene networks as a strategy to leverage high throughput gene expression queries. PLoS One 2010; 5:e12525. [PMID: 20824082 PMCID: PMC2932711 DOI: 10.1371/journal.pone.0012525] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 08/04/2010] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Large-scale gene expression studies have not yielded the expected insight into genetic networks that control complex processes. These anticipated discoveries have been limited not by technology, but by a lack of effective strategies to investigate the data in a manageable and meaningful way. Previous work suggests that using a pre-determined seed-network of gene relationships to query large-scale expression datasets is an effective way to generate candidate genes for further study and network expansion or enrichment. Based on the evolutionary conservation of gene relationships, we test the hypothesis that a seed network derived from studies of retinal cell determination in the fly, Drosophila melanogaster, will be an effective way to identify novel candidate genes for their role in mouse retinal development. METHODOLOGY/PRINCIPAL FINDINGS Our results demonstrate that a number of gene relationships regulating retinal cell differentiation in the fly are identifiable as pairwise correlations between genes from developing mouse retina. In addition, we demonstrate that our extracted seed-network of correlated mouse genes is an effective tool for querying datasets and provides a context to generate hypotheses. Our query identified 46 genes correlated with our extracted seed-network members. Approximately 54% of these candidates had been previously linked to the developing brain and 33% had been previously linked to the developing retina. Five of six candidate genes investigated further were validated by experiments examining spatial and temporal protein expression in the developing retina. CONCLUSIONS/SIGNIFICANCE We present an effective strategy for pursuing a systems biology approach that utilizes an evolutionary comparative framework between two model organisms, fly and mouse. Future implementation of this strategy will be useful to determine the extent of network conservation, not just gene conservation, between species and will facilitate the use of prior biological knowledge to develop rational systems-based hypotheses.
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Affiliation(s)
- Jeanne M Serb
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, Iowa, United States of America.
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242
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Biochemical and functional interaction of disrupted-in-schizophrenia 1 and amyloid precursor protein regulates neuronal migration during mammalian cortical development. J Neurosci 2010; 30:10431-40. [PMID: 20685985 DOI: 10.1523/jneurosci.1445-10.2010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Although clinically distinct, schizophrenia and Alzheimer's disease are common and devastating disorders that profoundly impair cognitive function. For Alzheimer's disease, key mechanistic insights have emerged from genetic studies that identified causative mutations in amyloid precursor protein (APP) and presenilin. Several genes have been associated with schizophrenia and other major psychoses, and understanding their normal functions will help elucidate the underlying causes of these disorders. One such gene is disrupted-in-schizophrenia 1 (DISC1). DISC1 and APP have been implicated separately in cortical development, with each having roles in both neuronal migration and neurite outgrowth. Here, we report a previously unrecognized biochemical and functional interaction between DISC1 and APP. Using in utero electroporation in the living rat brain, we show that DISC1 acts downstream of APP and Disabled-1 to regulate cortical precursor cell migration. Specifically, overexpression of DISC1 rescues the migration defect caused by a loss of APP expression. Moreover, knockdown of APP in cultured embryonic neurons results in altered subcellular localization of DISC1. Using transfected cells and normal brain tissue, we show that APP and DISC1 coimmunoprecipitate and that the intracellular domain of APP interacts with the N-terminal domain of DISC1. Based on these findings, we hypothesize that the APP cytoplasmic region transiently interacts with DISC1 to help regulate the translocation of DISC1 to the centrosome, where it plays a key role in controlling neuronal migration during cortical development.
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243
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Li H, Wang Z, Wang B, Guo Q, Dolios G, Tabuchi K, Hammer RE, Südhof TC, Wang R, Zheng H. Genetic dissection of the amyloid precursor protein in developmental function and amyloid pathogenesis. J Biol Chem 2010; 285:30598-605. [PMID: 20693289 DOI: 10.1074/jbc.m110.137729] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Proteolytic processing of the amyloid precursor protein (APP) generates large soluble APP derivatives, β-amyloid (Aβ) peptides, and APP intracellular domain. Expression of the extracellular sequences of APP or its Caenorhabditis elegans counterpart has been shown to be sufficient in partially rescuing the CNS phenotypes of the APP-deficient mice and the lethality of the apl-1 null C. elegans, respectively, leaving open the question as what is the role of the highly conserved APP intracellular domain? To address this question, we created an APP knock-in allele in which the mouse Aβ sequence was replaced by the human Aβ. A frameshift mutation was introduced that replaced the last 39 residues of the APP sequence. We demonstrate that the C-terminal mutation does not overtly affect APP processing and amyloid pathology. In contrast, crossing the mutant allele with APP-like protein 2 (APLP2)-null mice results in similar neuromuscular synapse defects and early postnatal lethality as compared with mice doubly deficient in APP and APLP2, demonstrating an indispensable role of the APP C-terminal domain in these development activities. Our results establish an essential function of the conserved APP intracellular domain in developmental regulation, and this activity can be genetically uncoupled from APP processing and Aβ pathogenesis.
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Affiliation(s)
- Hongmei Li
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas 77030, USA
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244
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Bergmans BA, Shariati SAM, Habets RLP, Verstreken P, Schoonjans L, Müller U, Dotti CG, De Strooper B. Neurons generated from APP/APLP1/APLP2 triple knockout embryonic stem cells behave normally in vitro and in vivo: lack of evidence for a cell autonomous role of the amyloid precursor protein in neuronal differentiation. Stem Cells 2010; 28:399-406. [PMID: 20049903 DOI: 10.1002/stem.296] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Alzheimer's disease amyloid precursor protein (APP) has been implicated in many neurobiologic processes, but supporting evidence remains indirect. Studies are confounded by the existence of two partially redundant APP homologues, APLP1 and APLP2. APP/APLP1/APLP2 triple knockout (APP tKO) mice display cobblestone lissencephaly and are perinatally lethal. To circumvent this problem, we generated APP triple knockout embryonic stem (ES) cells and differentiated these to APP triple knockout neurons in vitro and in vivo. In comparison with wild-type (WT) ES cell-derived neurons, APP tKO neurons formed equally pure neuronal cultures, had unaltered in vitro migratory capacities, had a similar acquisition of polarity, and were capable of extending long neurites and forming active excitatory synapses. These data were confirmed in vivo in chimeric mice with APP tKO neurons expressing the enhanced green fluorescent protein (eGFP) present in a WT background brain. The results suggest that the loss of the APP family of proteins has no major effect on these critical neuronal processes and that the apparent multitude of functions in which APP has been implicated might be characterized by molecular redundancy. Our stem cell culture provides an excellent tool to circumvent the problem of lack of viability of APP/APLP triple knockout mice and will help to explore the function of this intriguing protein further in vitro and in vivo.
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Affiliation(s)
- Bruno A Bergmans
- Laboratory of Neuronal Cell Biology and Gene Transfer, Leuven, Belgium
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245
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Dosunmu R, Wu J, Adwan L, Maloney B, Basha MR, McPherson CA, Harry GJ, Rice DC, Zawia NH, Lahiri DK. Lifespan profiles of Alzheimer's disease-associated genes and products in monkeys and mice. J Alzheimers Dis 2010; 18:211-30. [PMID: 19584442 DOI: 10.3233/jad-2009-1138] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is characterized by plaques of amyloid-beta (Abeta) peptide, cleaved from amyloid-beta protein precursor (AbetaPP). Our hypothesis is that lifespan profiles of AD-associated mRNA and protein levels in monkeys would differ from mice and that differential lifespan expression profiles would be useful to understand human AD pathogenesis. We compared profiles of AbetaPP mRNA, AbetaPP protein, and Abeta levels in rodents and primates. We also tracked a transcriptional regulator of the AbetaPP gene, specificity protein 1 (SP1), and the beta amyloid precursor cleaving enzyme (BACE1). In mice, AbetaPP and SP1 mRNA and their protein products were elevated late in life; Abeta levels declined in old age. In monkeys, SP1, AbetaPP, and BACE1 mRNA declined in old age, while protein products and Abeta levels rose. Proteolytic processing in both species did not match production of Abeta. In primates, AbetaPP and SP1 mRNA levels coordinate, but an inverse relationship exists with corresponding protein products as well as Abeta levels. Comparison of human DNA and mRNA sequences to monkey and mouse counterparts revealed structural features that may explain differences in transcriptional and translational processing. These findings are important for selecting appropriate models for AD and other age-related diseases.
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Affiliation(s)
- Remi Dosunmu
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA
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246
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Lee KJ, Moussa CEH, Lee Y, Sung Y, Howell BW, Turner RS, Pak DTS, Hoe HS. Beta amyloid-independent role of amyloid precursor protein in generation and maintenance of dendritic spines. Neuroscience 2010; 169:344-56. [PMID: 20451588 DOI: 10.1016/j.neuroscience.2010.04.078] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 04/28/2010] [Accepted: 04/30/2010] [Indexed: 10/19/2022]
Abstract
Synapse loss induced by amyloid beta (Abeta) is thought to be a primary contributor to cognitive decline in Alzheimer's disease. Abeta is generated by proteolysis of amyloid precursor protein (APP), a synaptic receptor whose physiological function remains unclear. In the present study, we investigated the role of APP in dendritic spine formation, which is known to be important for learning and memory. We found that overexpression of APP increased spine number, whereas knockdown of APP reduced spine density in cultured hippocampal neurons. This spine-promoting effect of APP required both the extracellular and intracellular domains of APP, and was accompanied by specific upregulation of the GluR2, but not the GluR1, subunit of AMPA receptors. In an in vivo experiment, we found that cortical layers II/III and hippocampal CA1 pyramidal neurons in 1 year-old APP-deficient mice had fewer and shorter dendritic spines than wild-type littermates. In contrast, transgenic mice overexpressing mutant APP exhibited increased spine density compared to control animals, though only at a young age prior to overaccumulation of soluble amyloid. Additionally, increased glutamate synthesis was observed in young APP transgenic brains, whereas glutamate levels were decreased and GABA levels were increased in APP-deficient mice. These results demonstrate that APP is important for promoting spine formation and is required for proper spine development.
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Affiliation(s)
- K J Lee
- Department of Pharmacology, Georgetown University Medical Center, 3900 Reservoir Road NW, Washington, DC 20057-1464, USA
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247
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Khalifa NB, Van Hees J, Tasiaux B, Huysseune S, Smith SO, Constantinescu SN, Octave JN, Kienlen-Campard P. What is the role of amyloid precursor protein dimerization? Cell Adh Migr 2010; 4:268-72. [PMID: 20400860 DOI: 10.4161/cam.4.2.11476] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Extensive research efforts have been conducted over the past decades to understand the processing of the Amyloid Precursor Protein (APP). APP cleavage leads to the production of the beta-amyloid peptide (Abeta), which is the major constituent of the amyloid core of senile plaques found in the brains of patients with Alzheimer disease (AD). Abeta is produced by the sequential cleavage of APP by beta- and gamma-secretases. Cleavage of APP by gamma-secretase also generates the APP Intracellular C-terminal Domain (AICD) peptide, which might be involved in regulation of gene transcription. Up to now, our understanding of the mechanisms controlling APP processing has been elusive. Recently, APP was found to form homo- or hetero-complexes with the APP-like proteins (APLPs), which belong to the same family and share some important structural properties with receptors having a single membrane spanning domain. Homodimerization of APP is driven by motifs present in the extracellular domain and possibly in the juxtamembrane and transmembrane (JM/TM) domains of the protein. These striking observations raise important questions about APP processing and function: How and where is APP dimerizing? What is the role of dimerization in APP processing and function? Can dimerization be targeted by small molecule therapeutics?
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Affiliation(s)
- Naouel Ben Khalifa
- Université catholique de Louvain, Institute of Neuroscience, Brussels, Belgium
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248
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Venkataramani V, Rossner C, Iffland L, Schweyer S, Tamboli IY, Walter J, Wirths O, Bayer TA. Histone deacetylase inhibitor valproic acid inhibits cancer cell proliferation via down-regulation of the alzheimer amyloid precursor protein. J Biol Chem 2010; 285:10678-89. [PMID: 20145244 PMCID: PMC2856276 DOI: 10.1074/jbc.m109.057836] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 02/05/2010] [Indexed: 11/06/2022] Open
Abstract
The beta-amyloid precursor protein (APP) represents a type I transmembrane glycoprotein that is ubiquitously expressed. In the brain, it is a key player in the molecular pathogenesis of Alzheimer disease. Its physiological function is however less well understood. Previous studies showed that APP is up-regulated in prostate, colon, pancreatic tumor, and oral squamous cell carcinoma. In this study, we show that APP has an essential role in growth control of pancreatic and colon cancer. Abundant APP staining was found in human pancreatic adenocarcinoma and colon cancer tissue. Interestingly, treating pancreatic and colon cancer cells with valproic acid (VPA, 2-propylpentanoic acid), a known histone deacetylase (HDAC) inhibitor, leads to up-regulation of GRP78, an endoplasmic reticulum chaperone immunoglobulin-binding protein. GRP78 is involved in APP maturation and inhibition of tumor cell growth by down-regulation of APP and secreted soluble APPalpha. Trichostatin A, a pan-HDAC inhibitor, also lowered APP and increased GRP78 levels. In contrast, treating cells with valpromide, a VPA derivative lacking HDAC inhibitory properties, had no effect on APP levels. VPA did not modify the level of epidermal growth factor receptor, another type I transmembrane protein, and APLP2, a member of the APP family, demonstrating the specificity of the VPA effect on APP. Small interfering RNA-mediated knockdown of APP also resulted in significantly decreased cell growth. Based on these observations, the data suggest that APP down-regulation via HDAC inhibition provides a novel mechanism for pancreatic and colon cancer therapy.
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Affiliation(s)
- Vivek Venkataramani
- From the Department of Molecular Psychiatry, Alzheimer Ph.D. Graduate School, and
| | - Christian Rossner
- From the Department of Molecular Psychiatry, Alzheimer Ph.D. Graduate School, and
| | - Lara Iffland
- From the Department of Molecular Psychiatry, Alzheimer Ph.D. Graduate School, and
| | - Stefan Schweyer
- Department of Pathology, University of Goettingen, 37075 Goettingen and
| | - Irfan Y. Tamboli
- the Department of Molecular Cell Biology, University of Bonn, 53127 Bonn, Germany
| | - Jochen Walter
- the Department of Molecular Cell Biology, University of Bonn, 53127 Bonn, Germany
| | - Oliver Wirths
- From the Department of Molecular Psychiatry, Alzheimer Ph.D. Graduate School, and
| | - Thomas A. Bayer
- From the Department of Molecular Psychiatry, Alzheimer Ph.D. Graduate School, and
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249
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Niwa M, Kamiya A, Murai R, Kubo KI, Gruber AJ, Tomita K, Lu L, Tomisato S, Jaaro-Peled H, Seshadri S, Hiyama H, Huang B, Kohda K, Noda Y, O'Donnell P, Nakajima K, Sawa A, Nabeshima T. Knockdown of DISC1 by in utero gene transfer disturbs postnatal dopaminergic maturation in the frontal cortex and leads to adult behavioral deficits. Neuron 2010; 65:480-9. [PMID: 20188653 DOI: 10.1016/j.neuron.2010.01.019] [Citation(s) in RCA: 236] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2010] [Indexed: 01/28/2023]
Abstract
Adult brain function and behavior are influenced by neuronal network formation during development. Genetic susceptibility factors for adult psychiatric illnesses, such as Neuregulin-1 and Disrupted-in-Schizophrenia-1 (DISC1), influence adult high brain functions, including cognition and information processing. These factors have roles during neurodevelopment and are likely to cooperate, forming pathways or "signalosomes." Here we report the potential to generate an animal model via in utero gene transfer in order to address an important question of how nonlethal deficits in early development may affect postnatal brain maturation and high brain functions in adulthood, which are impaired in various psychiatric illnesses such as schizophrenia. We show that transient knockdown of DISC1 in the pre- and perinatal stages, specifically in a lineage of pyramidal neurons mainly in the prefrontal cortex, leads to selective abnormalities in postnatal mesocortical dopaminergic maturation and behavioral abnormalities associated with disturbed cortical neurocircuitry after puberty.
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Affiliation(s)
- Minae Niwa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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250
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Frigerio CS, Fadeeva JV, Minogue AM, Citron M, Leuven FV, Stufenbiel M, Paganetti P, Selkoe DJ, Walsh DM. beta-Secretase cleavage is not required for generation of the intracellular C-terminal domain of the amyloid precursor family of proteins. FEBS J 2010; 277:1503-18. [PMID: 20163459 PMCID: PMC2847843 DOI: 10.1111/j.1742-4658.2010.07579.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The amyloid precursor family of proteins are of considerable interest, both because of their role in Alzheimer's disease pathogenesis and because of their normal physiological functions. In mammals, the amyloid precursor protein (APP) has two homologs, amyloid precursor-like protein (APLP) 1 and APLP2. All three proteins undergo ectodomain shedding and regulated intramembrane proteolysis, and important functions have been attributed to the full-length proteins, shed ectodomains, C-terminal fragments and intracellular domains (ICDs). One of the proteases that is known to cleave APP and that is essential for generation of the amyloid beta-protein is the beta-site APP-cleaving enzyme 1 (BACE1). Here, we investigated the effects of genetic manipulation of BACE1 on the processing of the APP family of proteins. BACE1 expression regulated the levels and species of full-length APLP1, APP and APLP2, of their shed ectodomains, and of their membrane-bound C-terminal fragments. In particular, APP processing appears to be tightly regulated, with changes in beta-cleaved APPs (APPsbeta) being compensated for by changes in alpha-cleaved APPs (APPsalpha). In contrast, the total levels of soluble cleaved APLP1 and APLP2 species were less tightly regulated, and fluctuated with BACE1 expression. Importantly, the production of ICDs for all three proteins was not decreased by loss of BACE1 activity. These results indicate that BACE1 is involved in regulating ectodomain shedding, maturation and trafficking of the APP family of proteins. Consequently, whereas inhibition of BACE1 is unlikely to adversely affect potential ICD-mediated signaling, it may alter other important facets of amyloid precursor-like protein/APP biology.
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Affiliation(s)
- Carlo Sala Frigerio
- Laboratory for Neurodegenerative Research, The Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Republic of Ireland
| | - Julia V. Fadeeva
- Department of Neurology, Harvard Medical School and Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, MA 02115
| | - Aedín M. Minogue
- Laboratory for Neurodegenerative Research, The Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Republic of Ireland
| | - Martin Citron
- Amgen Inc., Thousand Oaks, CA 91320-1799, Current affiliation: Eli Lilly and Company, Indianapolis, IN 46285
| | - Fred Van Leuven
- Department of Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Matthias Stufenbiel
- Nervous System Research, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Paolo Paganetti
- Nervous System Research, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Dennis J. Selkoe
- Department of Neurology, Harvard Medical School and Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, MA 02115
| | - Dominic M. Walsh
- Laboratory for Neurodegenerative Research, The Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Republic of Ireland
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