151
|
Bennett RE, Brody DL. Array tomography for the detection of non-dilated, injured axons in traumatic brain injury. J Neurosci Methods 2015; 245:25-36. [PMID: 25687633 DOI: 10.1016/j.jneumeth.2015.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 10/24/2022]
Abstract
BACKGROUND Axonal injury is a key feature of several types of brain trauma and neurological disease. However, in mice and humans, many axons are less than 500 nm in diameter which is at or below the resolution of most conventional light microscopic imaging methods. In moderate to severe forms of axon injury, damaged axons become dilated and therefore readily detectible by light microscopy. However, in more subtle forms of injury, the damaged axons may remain undilated and therefore difficult to detect. NEW METHOD Here we present a method for adapting array tomography for the identification and quantification of injured axons. In this technique, ultrathin (∼70 nm) plastic sections of tissue are prepared, labeled with axon injury-relevant antibodies and imaged using conventional epifluorescence. RESULTS To demonstrate the use of array-tomography-based methods, we determined that mice that received two closed-skull concussive traumatic brain injury impacts had significantly increased numbers of non-dilated axons that were immunoreactive for non-phosphorylated neurofilament (SMI-32; a marker of axonal injury), compared to sham mice (1682±628 versus 339±52 per mm(2), p=0.004, one-tailed Mann-Whitney U test). Tubulin loss was not evident (p=0.2063, one-tailed Mann-Whitney U test). Furthermore, mice that were subjected to more severe injury had a loss of tubulin in addition to both dilated and non-dilated SMI-32 immunoreactive axons indicating that this technique is suitable for the analysis of various injury conditions. COMPARISON WITH EXISTING METHOD With array tomography we could detect similar overall numbers of axons as electron microscopy, but accurate diameter measurements were limited to those with diameters >200 nm. Importantly, array tomography had greater sensitivity for detecting small non-dilated injured axons compared with conventional immunohistochemistry. CONCLUSION Imaging of individual axons and quantification of subtle axonal injury is possible using this array tomography method. This method may be most useful for the assessment of concussive injuries and other pathologies in which injured axons are not typically dilated. The ability to process moderately large volumes of tissue, label multiple proteins of interest, and automate analysis support array tomography as a useful alternative to electron microscopy.
Collapse
Affiliation(s)
- Rachel E Bennett
- Department of Neurology, Washington University in St. Louis, 660 S. Euclid Avenue, Saint Louis, MO 63110, USA
| | - David L Brody
- Department of Neurology, Washington University in St. Louis, 660 S. Euclid Avenue, Saint Louis, MO 63110, USA.
| |
Collapse
|
152
|
Abstract
The β-amyloid precursor protein (APP) plays a central role in the pathogenesis of Alzheimer's disease. APP is processed in neurons, but little is known about the relative contributions of presynaptic or postsynaptic compartments to the release of Aβ peptides. To address this issue, we transduced primary neurons from Sprague-Dawley rats or APP(-/-) mice (B6.129S7-App(tm1Dbo)/J) with lentiviral constructs expressing APP chimeras harboring targeting motifs from low-density lipoprotein receptor or neuron-glia cell-adhesion molecule to polarize expression to either dendritic or axonal membranes, respectively. Using imaging and quantitative biochemical approaches, we now report that APP selectively targeted to either axons or dendrites leads to the secretion of full-length Aβ peptides with significantly elevated release from dendritic compartments. These findings reveal that the enzymatic machinery required for production of Aβ peptides are operative both in presynaptic and postsynaptic compartments of primary neurons, leading to the suggestion that Aβ-mediated impairments in glutamatergic neurotransmission is the result of Aβ release from both local and distal neuronal compartments.
Collapse
|
153
|
Kukharsky MS, Ovchinnikov RK, Bachurin SO. Molecular aspects of the pathogenesis and current approaches to pharmacological correction of Alzheimer’s disease. Zh Nevrol Psikhiatr Im S S Korsakova 2015; 115:103-114. [DOI: 10.17116/jnevro20151156103-114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
154
|
Abstract
Interest in the amyloid precursor protein (APP) has increased in recent years due to its involvement in Alzheimer's disease. Since its molecular cloning, significant genetic and biochemical work has focused on the role of APP in the pathogenesis of this disease. Thus far, however, these studies have failed to deliver successful therapies. This suggests that understanding the basic biology of APP and its physiological role during development might be a crucial missing link for a better comprehension of Alzheimer's disease. Here, we present an overview of some of the key studies performed in various model organisms that have revealed roles for APP at different stages of neuronal development.
Collapse
Affiliation(s)
- Maya Nicolas
- VIB Center for the Biology of Disease, VIB, 3000 Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine, 3000 Leuven, Belgium Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, 3000 Leuven, Belgium
| | - Bassem A Hassan
- VIB Center for the Biology of Disease, VIB, 3000 Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine, 3000 Leuven, Belgium Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, 3000 Leuven, Belgium
| |
Collapse
|
155
|
Ciccotosto GD, James SA, Altissimo M, Paterson D, Vogt S, Lai B, de Jonge MD, Howard DL, Bush AI, Cappai R. Quantitation and localization of intracellular redox active metals by X-ray fluorescence microscopy in cortical neurons derived from APP and APLP2 knockout tissue. Metallomics 2014; 6:1894-904. [PMID: 25098278 DOI: 10.1039/c4mt00176a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The amyloid precursor protein (APP) gene family includes APP and the amyloid precursor-like proteins, APLP1 and APLP2. These proteins contain metal binding sites for copper, zinc and iron and are known to have physiological roles in modulating the metal homeostasis in brain cells. Here we report the application of X-ray fluorescence microscopy (XFM) to investigate the subcellular distribution patterns of the metal ions Cu, Zn, Fe, and Ca in individual neurons derived from APP and APLP2 knockout mice brains to further define their role in metal homeostasis. These studies add to the growing body of data that the APP family of proteins are metalloproteins that have shared as well as distinct effects on metals. As we continue to delineate the cellular effects of the APP family of proteins it is important to consider how metals are involved in their actions.
Collapse
Affiliation(s)
- Giuseppe D Ciccotosto
- Department of Pathology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
156
|
Zhang YQ, Chandra SS. Oligomerization of Cysteine String Protein alpha mutants causing adult neuronal ceroid lipofuscinosis. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2136-46. [PMID: 25064588 DOI: 10.1016/j.bbadis.2014.07.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 06/20/2014] [Accepted: 07/16/2014] [Indexed: 02/07/2023]
Abstract
Cysteine String Protein alpha (CSPα) is a palmitoylated, synaptic vesicle co-chaperone that is essential for neuroprotection. Two mutations in CSPα - L115R and L116Δ - cause adult neuronal ceroid lipofuscinosis (ANCL), a dominantly-inherited neurodegenerative disease. To elucidate the pathogenesis of ANCL, the intrinsic biochemical properties of human wildtype (WT) and disease mutant CSPα were examined. Mutant proteins purified from Escherichia coli exhibited high potency to oligomerize in a concentration, temperature, and time dependent manner, with L115R possessing the greatest potency. When freshly purified, ANCL mutant proteins displayed normal co-chaperone activity and substrate recognition similar to WT. However, co-chaperone activity was impaired for both CSPα mutants upon oligomerization. When WT and mutant CSPα were mixed together they co-oligomerized leading to an overall decrease of co-chaperone activity. The oligomerization properties of ANCL mutants were faithfully replicated in HEK 293T cells. Interestingly, the oligomers were covalently tagged by ubiquitination instead of palmitoylation. Taken together, ANCL mutations result in both a gain and partial loss-of-function.
Collapse
Affiliation(s)
- Yong-Quan Zhang
- Program for Cellular Neuroscience, Neurodegeneration and Repair, Department of Neurology, Yale School of Medicine, New Haven, CT 06536, USA.
| | - Sreeganga S Chandra
- Program for Cellular Neuroscience, Neurodegeneration and Repair, Department of Neurology, Yale School of Medicine, New Haven, CT 06536, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06536, USA.
| |
Collapse
|
157
|
Alzheimer's disease--a panorama glimpse. Int J Mol Sci 2014; 15:12631-50. [PMID: 25032844 PMCID: PMC4139864 DOI: 10.3390/ijms150712631] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/26/2014] [Accepted: 07/10/2014] [Indexed: 01/05/2023] Open
Abstract
The single-mutation of genes associated with Alzheimer's disease (AD) increases the production of Aβ peptides. An elevated concentration of Aβ peptides is prone to aggregation into oligomers and further deposition as plaque. Aβ plaques and neurofibrillary tangles are two hallmarks of AD. In this review, we provide a broad overview of the diverses sources that could lead to AD, which include genetic origins, Aβ peptides and tau protein. We shall discuss on tau protein and tau accumulation, which result in neurofibrillary tangles. We detail the mechanisms of Aβ aggregation, fibril formation and its polymorphism. We then show the possible links between Aβ and tau pathology. Furthermore, we summarize the structural data of Aβ and its precursor protein obtained via Nuclear Magnetic Resonance (NMR) or X-ray crystallography. At the end, we go through the C-terminal and N-terminal truncated Aβ variants. We wish to draw reader's attention to two predominant and toxic Aβ species, namely Aβ4-42 and pyroglutamate amyloid-beta peptides, which have been neglected for more than a decade and may be crucial in Aβ pathogenesis due to their dominant presence in the AD brain.
Collapse
|
158
|
Vassar R, Kuhn PH, Haass C, Kennedy ME, Rajendran L, Wong PC, Lichtenthaler SF. Function, therapeutic potential and cell biology of BACE proteases: current status and future prospects. J Neurochem 2014; 130:4-28. [PMID: 24646365 PMCID: PMC4086641 DOI: 10.1111/jnc.12715] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 01/18/2023]
Abstract
The β-site APP cleaving enzymes 1 and 2 (BACE1 and BACE2) were initially identified as transmembrane aspartyl proteases cleaving the amyloid precursor protein (APP). BACE1 is a major drug target for Alzheimer's disease because BACE1-mediated cleavage of APP is the first step in the generation of the pathogenic amyloid-β peptides. BACE1, which is highly expressed in the nervous system, is also required for myelination by cleaving neuregulin 1. Several recent proteomic and in vivo studies using BACE1- and BACE2-deficient mice demonstrate a much wider range of physiological substrates and functions for both proteases within and outside of the nervous system. For BACE1 this includes axon guidance, neurogenesis, muscle spindle formation, and neuronal network functions, whereas BACE2 was shown to be involved in pigmentation and pancreatic β-cell function. This review highlights the recent progress in understanding cell biology, substrates, and functions of BACE proteases and discusses the therapeutic options and potential mechanism-based liabilities, in particular for BACE inhibitors in Alzheimer's disease. The protease BACE1 is a major drug target in Alzheimer disease. Together with its homolog BACE2, both proteases have an increasing number of functions within and outside of the nervous system. This review highlights recent progress in understanding cell biology, substrates, and functions of BACE proteases and discusses the therapeutic options and potential mechanism-based liabilities, in particular for BACE inhibitors in Alzheimer disease.
Collapse
Affiliation(s)
- Robert Vassar
- Department of Cell and Molecular Biology, Feinberg University School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Peer-Hendrik Kuhn
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Neuroproteomics, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Institute for Advanced Study, Technische Universität München, Garching, Germany
| | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
- Adolf-Butenandt Institute, Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany
| | - Matthew E. Kennedy
- Neurosciences, Merck Research Labs, Boston, Massachusetts, USA
- Division of Psychiatry Research, University of Zurich, Zurich, Switzerland
| | - Lawrence Rajendran
- Systems and Cell Biology of Neurodegeneration, Division of Psychiatry Research, University of Zurich, Zurich, Switzerland
- Graduate programs of the Zurich Center for Integrative Human Physiology and Zurich Neuroscience Center, University of Zurich, Zurich, Switzerland
| | - Philip C. Wong
- Departments of Pathology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Stefan F. Lichtenthaler
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Neuroproteomics, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Institute for Advanced Study, Technische Universität München, Garching, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| |
Collapse
|
159
|
Heiker JT, Kunath A, Kosacka J, Flehmig G, Knigge A, Kern M, Stumvoll M, Kovacs P, Blüher M, Klöting N. Identification of genetic loci associated with different responses to high-fat diet-induced obesity in C57BL/6N and C57BL/6J substrains. Physiol Genomics 2014; 46:377-84. [DOI: 10.1152/physiolgenomics.00014.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We have recently demonstrated that C57BL/6NTac and C57BL/6JRj substrains are significantly different in their response to high-fat diet-induced obesity (DIO). The C57BL/6JRj substrain seems to be protected from DIO and genetic differences between C57BL/6J and C57BL/6N substrains at 11 single nucleotide polymorphism (SNP) loci have been identified. To define genetic variants as well as differences in parameters of glucose homeostasis and insulin sensitivity between C57BL/6NTac and C57BL/6JRj substrains that may explain the different response to DIO, we analyzed 208 first backcross (BC1) hybrids of C57BL/6NTac and C57BL/6JRj [(C57BL/6NTac × C57BL/6JRj)F1 × C57BL/6NTac] mice. Body weight, epigonadal and subcutaneous fat mass, circulating leptin, as well as parameters of glucose metabolism were measured after 10 wk of high-fat diet (HFD). Genetic profiling of BC1 hybrids were performed using TaqMan SNP genotyping assays. Furthermore, to assess whether SNP polymorphisms could affect mRNA level, we carried out gene expression analysis in murine liver samples. Human subcutaneous adipose tissue was used to verify murine data of SNAP29. We identified four sex-specific variants that are associated with the extent of HFD-induced weight gain and fat depot mass. BC1 hybrids carrying the combination of risk or beneficial alleles exhibit the phenotypical extremes of the parental strains. Murine and human SC expression analysis revealed Snap29 as strongest candidate. Our data indicate an important role of these loci in responsiveness to HFD-induced obesity and suggest genes of the synaptic vesicle release system such as Snap29 being involved in the regulation of high-fat DIO.
Collapse
Affiliation(s)
- John T. Heiker
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
- Institute of Biochemistry, Leipzig University, Leipzig, Germany
| | - Anne Kunath
- IFB AdiposityDiseases, Junior Research Group 2 “Animal models of obesity”, Leipzig University, Leipzig, Germany; and
| | - Joanna Kosacka
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
| | - Gesine Flehmig
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
- IFB AdiposityDiseases, Leipzig University, Leipzig, Germany
| | - Anja Knigge
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
| | - Matthias Kern
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
| | - Michael Stumvoll
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
- IFB AdiposityDiseases, Leipzig University, Leipzig, Germany
| | - Peter Kovacs
- IFB AdiposityDiseases, Leipzig University, Leipzig, Germany
| | - Matthias Blüher
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
- IFB AdiposityDiseases, Leipzig University, Leipzig, Germany
| | - Nora Klöting
- Department of Medicine, Endocrinology and Diabetes, Leipzig University, Leipzig, Germany
- IFB AdiposityDiseases, Junior Research Group 2 “Animal models of obesity”, Leipzig University, Leipzig, Germany; and
| |
Collapse
|
160
|
Mayer MC, Kaden D, Schauenburg L, Hancock MA, Voigt P, Roeser D, Barucker C, Than ME, Schaefer M, Multhaup G. Novel zinc-binding site in the E2 domain regulates amyloid precursor-like protein 1 (APLP1) oligomerization. J Biol Chem 2014; 289:19019-30. [PMID: 24855651 DOI: 10.1074/jbc.m114.570382] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The amyloid precursor protein (APP) and the APP-like proteins 1 and 2 (APLP1 and APLP2) are a family of multidomain transmembrane proteins possessing homo- and heterotypic contact sites in their ectodomains. We previously reported that divalent metal ions dictate the conformation of the extracellular APP E2 domain (Dahms, S. O., Könnig, I., Roeser, D., Gührs, K.-H., Mayer, M. C., Kaden, D., Multhaup, G., and Than, M. E. (2012) J. Mol. Biol. 416, 438-452), but unresolved is the nature and functional importance of metal ion binding to APLP1 and APLP2. We found here that zinc ions bound to APP and APLP1 E2 domains and mediated their oligomerization, whereas the APLP2 E2 domain interacted more weakly with zinc possessing a less surface-exposed zinc-binding site, and stayed monomeric. Copper ions bound to E2 domains of all three proteins. Fluorescence resonance energy transfer (FRET) analyses examined the effect of metal ion binding to APP and APLPs in the cellular context in real time. Zinc ions specifically induced APP and APLP1 oligomerization and forced APLP1 into multimeric clusters at the plasma membrane consistent with zinc concentrations in the blood and brain. The observed effects were mediated by a novel zinc-binding site within the APLP1 E2 domain as APLP1 deletion mutants revealed. Based upon its cellular localization and its dominant response to zinc ions, APLP1 is mainly affected by extracellular zinc among the APP family proteins. We conclude that zinc binding and APP/APLP oligomerization are intimately linked, and we propose that this represents a novel mechanism for regulating APP/APLP protein function at the molecular level.
Collapse
Affiliation(s)
- Magnus C Mayer
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Daniela Kaden
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Linda Schauenburg
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Mark A Hancock
- the Department of Pharmacology and Therapeutics, McGill University Montreal, Montreal, Quebec H3G 1Y6, Canada
| | - Philipp Voigt
- the Molekulare Pharmakologie und Zellbiologie, Thielallee 67-73, Neurowissenschaftliches Forschungszentrum, Charité-Universitätsmedizin Berlin, 14195 Berlin, Germany
| | - Dirk Roeser
- the Leibniz Institute for Age Research, Protein Crystallography Group, Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany, and
| | - Christian Barucker
- the Department of Pharmacology and Therapeutics, McGill University Montreal, Montreal, Quebec H3G 1Y6, Canada
| | - Manuel E Than
- the Leibniz Institute for Age Research, Protein Crystallography Group, Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany, and
| | - Michael Schaefer
- the Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Medizinische Fakultät der Universität Leipzig, Härtelstrasse 16-18, 04107 Leipzig, Germany
| | - Gerhard Multhaup
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany, the Department of Pharmacology and Therapeutics, McGill University Montreal, Montreal, Quebec H3G 1Y6, Canada,
| |
Collapse
|
161
|
Fogel H, Frere S, Segev O, Bharill S, Shapira I, Gazit N, O'Malley T, Slomowitz E, Berdichevsky Y, Walsh DM, Isacoff EY, Hirsch JA, Slutsky I. APP homodimers transduce an amyloid-β-mediated increase in release probability at excitatory synapses. Cell Rep 2014; 7:1560-1576. [PMID: 24835997 DOI: 10.1016/j.celrep.2014.04.024] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 03/12/2014] [Accepted: 04/12/2014] [Indexed: 10/25/2022] Open
Abstract
Accumulation of amyloid-β peptides (Aβ), the proteolytic products of the amyloid precursor protein (APP), induces a variety of synaptic dysfunctions ranging from hyperactivity to depression that are thought to cause cognitive decline in Alzheimer's disease. While depression of synaptic transmission has been extensively studied, the mechanisms underlying synaptic hyperactivity remain unknown. Here, we show that Aβ40 monomers and dimers augment release probability through local fine-tuning of APP-APP interactions at excitatory hippocampal boutons. Aβ40 binds to the APP, increases the APP homodimer fraction at the plasma membrane, and promotes APP-APP interactions. The APP activation induces structural rearrangements in the APP/Gi/o-protein complex, boosting presynaptic calcium flux and vesicle release. The APP growth-factor-like domain (GFLD) mediates APP-APP conformational changes and presynaptic enhancement. Thus, the APP homodimer constitutes a presynaptic receptor that transduces signal from Aβ40 to glutamate release. Excessive APP activation may initiate a positive feedback loop, contributing to hippocampal hyperactivity in Alzheimer's disease.
Collapse
Affiliation(s)
- Hilla Fogel
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Samuel Frere
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Oshik Segev
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Shashank Bharill
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Ilana Shapira
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Neta Gazit
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Tiernan O'Malley
- Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Dublin 4, Republic of Ireland; Laboratory for Neurodegenerative Research, Center for Neurologic Diseases, Brigham & Women's Hospital, Harvard Institutes of Medicine, Boston, MA 02115, USA
| | - Edden Slomowitz
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Yevgeny Berdichevsky
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Dominic M Walsh
- Laboratory for Neurodegenerative Research, Center for Neurologic Diseases, Brigham & Women's Hospital, Harvard Institutes of Medicine, Boston, MA 02115, USA
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Joel A Hirsch
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Inna Slutsky
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel.
| |
Collapse
|
162
|
Ayton S, Zhang M, Roberts BR, Lam LQ, Lind M, McLean C, Bush AI, Frugier T, Crack PJ, Duce JA. Ceruloplasmin and β-amyloid precursor protein confer neuroprotection in traumatic brain injury and lower neuronal iron. Free Radic Biol Med 2014; 69:331-7. [PMID: 24509156 DOI: 10.1016/j.freeradbiomed.2014.01.041] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/10/2014] [Accepted: 01/31/2014] [Indexed: 10/25/2022]
Abstract
Traumatic brain injury (TBI) is in part complicated by pro-oxidant iron elevation independent of brain hemorrhage. Ceruloplasmin (CP) and β-amyloid protein precursor (APP) are known neuroprotective proteins that reduce oxidative damage through iron regulation. We surveyed iron, CP, and APP in brain tissue from control and TBI-affected patients who were stratified according to time of death following injury. We observed CP and APP induction after TBI accompanying iron accumulation. Elevated APP and CP expression was also observed in a mouse model of focal cortical contusion injury concomitant with iron elevation. To determine if changes in APP or CP were neuroprotective we employed the same TBI model on APP(-/-) and CP(-/-) mice and found that both exhibited exaggerated infarct volume and iron accumulation postinjury. Evidence supports a regulatory role of both proteins in defence against iron-induced oxidative damage after TBI, which presents as a tractable therapeutic target.
Collapse
Affiliation(s)
- Scott Ayton
- Oxidation Biology Unit, The Florey Institute of Neuroscience and Mental Health
| | - Moses Zhang
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Blaine R Roberts
- Oxidation Biology Unit, The Florey Institute of Neuroscience and Mental Health
| | - Linh Q Lam
- Oxidation Biology Unit, The Florey Institute of Neuroscience and Mental Health
| | - Monica Lind
- Oxidation Biology Unit, The Florey Institute of Neuroscience and Mental Health
| | - Catriona McLean
- Department of Pathology, and The University of Melbourne, Parkville, VIC 3010, Australia
| | - Ashley I Bush
- Oxidation Biology Unit, The Florey Institute of Neuroscience and Mental Health; Department of Pathology, and The University of Melbourne, Parkville, VIC 3010, Australia
| | - Tony Frugier
- Department of Anatomy and Cell Biology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Peter J Crack
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, VIC 3010, Australia
| | - James A Duce
- Oxidation Biology Unit, The Florey Institute of Neuroscience and Mental Health; School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, North Yorkshire, UK.
| |
Collapse
|
163
|
Weyer SW, Zagrebelsky M, Herrmann U, Hick M, Ganss L, Gobbert J, Gruber M, Altmann C, Korte M, Deller T, Müller UC. Comparative analysis of single and combined APP/APLP knockouts reveals reduced spine density in APP-KO mice that is prevented by APPsα expression. Acta Neuropathol Commun 2014; 2:36. [PMID: 24684730 PMCID: PMC4023627 DOI: 10.1186/2051-5960-2-36] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 03/07/2014] [Indexed: 11/21/2022] Open
Abstract
Synaptic dysfunction and synapse loss are key features of Alzheimer's pathogenesis. Previously, we showed an essential function of APP and APLP2 for synaptic plasticity, learning and memory. Here, we used organotypic hippocampal cultures to investigate the specific role(s) of APP family members and their fragments for dendritic complexity and spine formation of principal neurons within the hippocampus. Whereas CA1 neurons from APLP1-KO or APLP2-KO mice showed normal neuronal morphology and spine density, APP-KO mice revealed a highly reduced dendritic complexity in mid-apical dendrites. Despite unaltered morphology of APLP2-KO neurons, combined APP/APLP2-DKO mutants showed an additional branching defect in proximal apical dendrites, indicating redundancy and a combined function of APP and APLP2 for dendritic architecture. Remarkably, APP-KO neurons showed a pronounced decrease in spine density and reductions in the number of mushroom spines. No further decrease in spine density, however, was detectable in APP/APLP2-DKO mice. Mechanistically, using APPsα-KI mice lacking transmembrane APP and expressing solely the secreted APPsα fragment we demonstrate that APPsα expression alone is sufficient to prevent the defects in spine density observed in APP-KO mice. Collectively, these studies reveal a combined role of APP and APLP2 for dendritic architecture and a unique function of secreted APPs for spine density.
Collapse
Affiliation(s)
- Sascha W Weyer
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
| | - Marta Zagrebelsky
- TU Braunschweig, Zoological Institute, Cellular Neurobiology, Spielmannstr. 7, Braunschweig D-38106, Germany
| | - Ulrike Herrmann
- TU Braunschweig, Zoological Institute, Cellular Neurobiology, Spielmannstr. 7, Braunschweig D-38106, Germany
| | - Meike Hick
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
| | - Lennard Ganss
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
- Present address: Department of Applied Tumor Biology, Ruprecht-Karls University Heidelberg, Institute of Pathology, University of Heidelberg, Heidelberg D-69120, Germany
| | - Julia Gobbert
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
| | - Morna Gruber
- Goethe University Frankfurt, Institute of Clinical Neuroanatomy, Neuroscience Center, Theodor-Stern-Kai 7, Frankfurt am Main D-60596, Germany
| | - Christine Altmann
- Goethe University Frankfurt, Institute of Clinical Neuroanatomy, Neuroscience Center, Theodor-Stern-Kai 7, Frankfurt am Main D-60596, Germany
| | - Martin Korte
- TU Braunschweig, Zoological Institute, Cellular Neurobiology, Spielmannstr. 7, Braunschweig D-38106, Germany
| | - Thomas Deller
- Goethe University Frankfurt, Institute of Clinical Neuroanatomy, Neuroscience Center, Theodor-Stern-Kai 7, Frankfurt am Main D-60596, Germany
| | - Ulrike C Müller
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
| |
Collapse
|
164
|
Dawkins E, Small DH. Insights into the physiological function of the β-amyloid precursor protein: beyond Alzheimer's disease. J Neurochem 2014; 129:756-69. [PMID: 24517464 PMCID: PMC4314671 DOI: 10.1111/jnc.12675] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 02/02/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
Abstract
The β-amyloid precursor protein (APP) has been extensively studied for its role as the precursor of the β-amyloid protein (Aβ) of Alzheimer's disease. However, the normal function of APP remains largely unknown. This article reviews studies on the structure, expression and post-translational processing of APP, as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms. This article reviews studies on the structure, expression and post-translational processing of β-amyloid precursor protein (APP), as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms.
Collapse
Affiliation(s)
- Edgar Dawkins
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
| | | |
Collapse
|
165
|
Peggion C, Sorgato MC, Bertoli A. Prions and prion-like pathogens in neurodegenerative disorders. Pathogens 2014; 3:149-63. [PMID: 25437612 PMCID: PMC4235734 DOI: 10.3390/pathogens3010149] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 01/24/2014] [Accepted: 02/01/2014] [Indexed: 12/24/2022] Open
Abstract
Prions are unique elements in biology, being able to transmit biological information from one organism to another in the absence of nucleic acids. They have been identified as self-replicating proteinaceous agents responsible for the onset of rare and fatal neurodegenerative disorders—known as transmissible spongiform encephalopathies, or prion diseases—which affect humans and other animal species. More recently, it has been proposed that other proteins associated with common neurodegenerative disorders, such as Alzheimer’s and Parkinson’s disease, can self-replicate like prions, thus sustaining the spread of neurotoxic entities throughout the nervous system. Here, we review findings that have contributed to expand the prion concept, and discuss if the involved toxic species can be considered bona fide prions, including the capacity to infect other organisms, or whether these pathogenic aggregates share with prions only the capability to self-replicate.
Collapse
Affiliation(s)
- Caterina Peggion
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35131, Italy.
| | - Maria Catia Sorgato
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35131, Italy.
| | - Alessandro Bertoli
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35131, Italy.
| |
Collapse
|
166
|
Alzheimer's disease therapeutics targeted to the control of amyloid precursor protein translation: maintenance of brain iron homeostasis. Biochem Pharmacol 2014; 88:486-94. [PMID: 24513321 DOI: 10.1016/j.bcp.2014.01.032] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/16/2014] [Accepted: 01/22/2014] [Indexed: 11/20/2022]
Abstract
The neurotoxicity of amyloid beta (Aβ), a major cleavage product of the amyloid precursor protein (APP), is enhanced by iron, as found in the amyloid plaques of Alzheimer's disease (AD) patients. By contrast, the long-known neuroprotective activity of APP is evident after α-secretase cleavage of the precursor to release sAPPα, and depends on the iron export actions of APP itself. The latter underlie its neurotrophic and protective effects in facilitating the homeostatic actions of ferroportin mediated-iron export. Thus APP-dependent iron export may alleviate oxidative stress by minimizing labile iron thus protecting neurons from iron overload during stroke and hemorrhage. Consistent with this, altered phosphorylation of iron-regulatory protein-1 (IRP1) and its signaling processes play a critical role in modulating APP translation via the 5' untranslated region (5'UTR) of its transcript. The APP 5'UTR region encodes a functional iron-responsive element (IRE) RNA stem loop that represents a potential target for modulating APP production. Targeted regulation of APP gene expression via the modulation of 5'UTR sequence function represents a novel approach for the potential treatment of AD since altering APP translation can be used to improve both the protective brain iron balance and provide anti-amyloid efficacy. Approved drugs including paroxetine and desferrioxamine and several novel compounds have been identified that suppress abnormal metal-promoted Aβ accumulation with a subset of these acting via APP 5'UTR-dependent mechanisms to modulate APP translation and cleavage to generate the non-toxic sAPPα.
Collapse
|
167
|
Sorrentino P, Iuliano A, Polverino A, Jacini F, Sorrentino G. The dark sides of amyloid in Alzheimer's disease pathogenesis. FEBS Lett 2014; 588:641-52. [PMID: 24491999 DOI: 10.1016/j.febslet.2013.12.038] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/06/2013] [Accepted: 12/20/2013] [Indexed: 11/15/2022]
Abstract
Although widely explored, the pathogenesis of Alzheimer's disease (AD) has yet to be cleared. Over the past twenty years the so call amyloid cascade hypothesis represented the main research paradigm in AD pathogenesis. In spite of its large consensus, the proposed role of β-amyloid (Aβ) remain to be elucidated. Many evidences are starting to cast doubt on Aβ as the primary causative factor in AD. For instance, Aβ is deposited in the brain following many different kinds of injury. Also, concentration of Aβ needed to induce toxicity in vitro are never reached in vivo. In this review we propose an amyloid-independent interpretation of several AD pathogenic features, such as synaptic plasticity, endo-lysosomal trafficking, cell cycle regulation and neuronal survival.
Collapse
Affiliation(s)
- Pierpaolo Sorrentino
- Dipartimento di Neuroscienze e Scienze Riproduttive ed Odontostomatologiche, Università degli Studi di Napoli Federico II, Naples, Italy
| | - Antonietta Iuliano
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy; Istituto di Diagnosi e Cura Hermitage Capodimonte, Naples, Italy
| | - Arianna Polverino
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy; Istituto di Diagnosi e Cura Hermitage Capodimonte, Naples, Italy
| | - Francesca Jacini
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy; Istituto di Diagnosi e Cura Hermitage Capodimonte, Naples, Italy
| | - Giuseppe Sorrentino
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy; Istituto di Diagnosi e Cura Hermitage Capodimonte, Naples, Italy.
| |
Collapse
|
168
|
Needham BE, Ciccotosto GD, Cappai R. Combined deletions of amyloid precursor protein and amyloid precursor-like protein 2 reveal different effects on mouse brain metal homeostasis. Metallomics 2014; 6:598-603. [PMID: 24448592 DOI: 10.1039/c3mt00358b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Alterations to the expression of the Amyloid Precursor Protein (APP) and its paralogue Amyloid Precursor-Like Protein 2 (APLP2) affect metal homeostasis in vitro and in vivo. Analysis of the in vivo effects of the APP and APLP2 knockouts on metal homeostasis has been restricted to APP and APLP2 single knockout mice, and up to12 month old animals. To define the redundancy and inter-relationship between the APP and APLP2 genes as regulators of metal homeostasis, and how this is influenced by aging, we investigated copper, iron, zinc and manganese levels in APP and APLP2 single knockout mice as well as homozygous:hemizygous knockout mice at 3, 12 and 18 plus months of age. These studies identified age and genotype dependent changes in metal levels, and established differences in the relative roles played by APP and APLP2 in modulating metal homeostasis.
Collapse
Affiliation(s)
- B Elise Needham
- Department of Pathology, The University of Melbourne, VIC 3010, Australia.
| | | | | |
Collapse
|
169
|
Abstract
Ubiquitin-dependent proteolysis is a major mechanism that downregulates misfolded proteins or those that have finished a programmed task. In the last two decades, neddylation has emerged as a major regulatory pathway for ubiquitination. Central to the neddylation pathway is the amyloid precursor protein (APP)-binding protein APP-BP1, which together with Uba3, plays an analogous role to the ubiquitin-activating enzyme E1 in nedd8 activation. Activated nedd8 covalently modifies and activates a major class of ubiquitin ligases called Cullin-RING ligases (CRLs). New evidence suggests that neddylation also modifies Type-1 transmembrane receptors such as APP. Here we review the functions of neddylation and summarize evidence suggesting that dysfunction of neddylation is involved in Alzheimer's disease.
Collapse
Affiliation(s)
- Yuzhi Chen
- Department of Geriatrics and Department of Neurobiology & Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
| | | | | |
Collapse
|
170
|
Alzheimer’s Disease and Frontotemporal Lobar Degeneration: Mouse Models. NEURODEGENER DIS 2014. [DOI: 10.1007/978-1-4471-6380-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
171
|
Wu G, Miller RA, Connolly B, Marcus J, Renger J, Savage MJ. Pyroglutamate-Modified Amyloid-� Protein Demonstrates Similar Properties in an Alzheimer's Disease Familial Mutant Knock-In Mouse and Alzheimer's Disease Brain. NEURODEGENER DIS 2014; 14:53-66. [DOI: 10.1159/000353634] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 06/11/2013] [Indexed: 11/19/2022] Open
|
172
|
Matsuki T, Chen J, Howell BW. Acute inactivation of the serine-threonine kinase Stk25 disrupts neuronal migration. Neural Dev 2013; 8:21. [PMID: 24225308 PMCID: PMC3874637 DOI: 10.1186/1749-8104-8-21] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 11/05/2013] [Indexed: 11/16/2022] Open
Abstract
Background Neuronal migration involves the directional migration of immature neurons. During much of the migration period these neurons are polarized with defined leading and trailing processes. Stk25 has been shown to bind to the LKB1 activator STRAD and regulate neuronal polarization and dendritogenesis in an opposing manner to Reelin-Dab1 signaling. It is not known, however, whether Stk25 controls neuronal migration, a key developmental process regulated by Reelin-Dab1 signal transduction. Findings Here we find that while constitutive Stk25 deficiency does not lead to neuronal phenotypes, acute reduction by either Cre-mediated gene inactivation or by knockdown causes a developmental neuronal migration error. Furthermore, we find that knockdown of LKB1, STRAD and GM130, molecules that have previously been implicated with Stk25, causes similar aberrations in neuronal migration. Conclusions Loss of Stk25 function early in development likely leads to functional compensation for its roles in neuronal development. Stk25 regulates neuronal positioning, possibly as part of the LKB1-STRAD-Stk25-GM130 pathway that was previously shown to be important for neuronal polarization.
Collapse
Affiliation(s)
| | | | - Brian W Howell
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, 750 E, Adams St, Syracuse, NY 13210, USA.
| |
Collapse
|
173
|
Convergence of synapses, endosomes, and prions in the biology of neurodegenerative diseases. Int J Cell Biol 2013; 2013:141083. [PMID: 24307901 PMCID: PMC3838826 DOI: 10.1155/2013/141083] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/23/2013] [Indexed: 11/17/2022] Open
Abstract
Age-related misfolding and aggregation of disease-linked proteins in selective brain regions is a characteristic of neurodegenerative diseases. Although neuropathological aggregates that characterize these various diseases are found at sites other than synapses, increasing evidence supports the idea that synapses are where the pathogenesis begins. Understanding these diseases is hampered by our lack of knowledge of what the normal functions of these proteins are and how they are affected by aging. Evidence has supported the idea that neurodegenerative disease-linked proteins have a common propensity for prion protein-like cell-to-cell propagation. However, it is not thought that the prion-like quality of these proteins/peptides that allows their cell-to-cell transmission implies a role for human-to-human spread in common age-related neurodegenerative diseases. It will be important to better understand the molecular and cellular mechanisms governing the role of these aggregating proteins in neural function, especially at synapses, how their propagation occurs and how pathogenesis is promoted by aging.
Collapse
|
174
|
Choi HY, Liu Y, Tennert C, Sugiura Y, Karakatsani A, Kröger S, Johnson EB, Hammer RE, Lin W, Herz J. APP interacts with LRP4 and agrin to coordinate the development of the neuromuscular junction in mice. eLife 2013; 2:e00220. [PMID: 23986861 PMCID: PMC3748711 DOI: 10.7554/elife.00220] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 07/18/2013] [Indexed: 12/22/2022] Open
Abstract
ApoE, ApoE receptors and APP cooperate in the pathogenesis of Alzheimer’s disease. Intriguingly, the ApoE receptor LRP4 and APP are also required for normal formation and function of the neuromuscular junction (NMJ). In this study, we show that APP interacts with LRP4, an obligate co-receptor for muscle-specific tyrosine kinase (MuSK). Agrin, a ligand for LRP4, also binds to APP and co-operatively enhances the interaction of APP with LRP4. In cultured myotubes, APP synergistically increases agrin-induced acetylcholine receptor (AChR) clustering. Deletion of the transmembrane domain of LRP4 (LRP4 ECD) results in growth retardation of the NMJ, and these defects are markedly enhanced in APP−/−;LRP4ECD/ECD mice. Double mutant NMJs are significantly reduced in size and number, resulting in perinatal lethality. Our findings reveal novel roles for APP in regulating neuromuscular synapse formation through hetero-oligomeric interaction with LRP4 and agrin and thereby provide new insights into the molecular mechanisms that govern NMJ formation and maintenance. DOI:http://dx.doi.org/10.7554/eLife.00220.001 One of the hallmarks of Alzheimer’s disease is the formation of plaques in the brain by a protein called β-amyloid. This protein is generated by the cleavage of a precursor protein, and mutations in the gene that encodes amyloid precursor protein greatly increase the risk of developing a familial, early-onset form of Alzheimer’s disease in middle age. Individuals with a particular variant of a lipoprotein called ApoE (ApoE4) are also more likely to develop Alzheimer’s disease at a younger age than the rest of the population. Due to its prevalence—approximately 20% of the world’s population are carriers of at least one allele—ApoE4 is the single-most important risk factor for the late-onset form of Alzheimer’s disease. Amyloid precursor protein and the receptors for ApoE—in particular one called LRP4—are also essential for the development of the specialized synapse that forms between motor neurons and muscles. However, the mechanisms by which they, individually or together, contribute to the formation of these neuromuscular junctions are incompletely understood. Now, Choi et al. have shown that amyloid precursor protein and LRP4 interact at the developing neuromuscular junction. A protein called agrin, which is produced by motor neurons and which must bind to LRP4 to induce neuromuscular junction formation, also binds directly to amyloid precursor protein. This latter interaction leads to the formation of a complex between LRP4 and amyloid precursor protein that robustly promotes the formation of the neuromuscular junction. Mutations that remove the part of LRP4 that anchors it to the cell membrane weaken this complex and thus reduce the development of neuromuscular junctions in mice, especially if the animals also lack amyloid precursor protein. These three proteins thus seem to influence the development and maintenance of neuromuscular junctions by regulating the activity of a fourth protein, called MuSK, which is present on the surface of muscle cells. Activation of MuSK by agrin bound to LRP4 promotes the clustering of acetylcholine receptors in the membrane, which is a crucial step in the formation of the neuromuscular junction. Intriguingly, Choi et al. have now shown that amyloid precursor protein can, by interacting directly with LRP4, also activate MuSK even in the absence of agrin, albeit only to a small extent. The work of Choi et al. suggests that the complex formed between agrin, amyloid precursor protein and LRP4 helps to focus the activation of MuSK, and thus the clustering of acetylcholine receptors, to the site of the developing neuromuscular junction. Since all four proteins are also found in the central nervous system, similar processes might well be at work during the development and maintenance of synapses in the brain. Further studies of these interactions, both at the neuromuscular junction and in the brain, should shed new light on both normal synapse formation and the synaptic dysfunction that is seen in Alzheimer’s disease. DOI:http://dx.doi.org/10.7554/eLife.00220.002
Collapse
Affiliation(s)
- Hong Y Choi
- Department of Molecular Genetics , University of Texas Southwestern Medical Center , Dallas , United States
| | | | | | | | | | | | | | | | | | | |
Collapse
|
175
|
Small DH, Hu Y, Bolós M, Dawkins E, Foa L, Young KM. β-Amyloid precursor protein: function in stem cell development and Alzheimer's disease brain. NEURODEGENER DIS 2013; 13:96-8. [PMID: 23942027 DOI: 10.1159/000353686] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 05/19/2013] [Indexed: 11/19/2022] Open
Abstract
Stem cell therapy may be a suitable approach for the treatment of many neurodegenerative diseases. However, one major impediment to the development of successful cell-based therapies is our limited understanding of the mechanisms that instruct neural stem cell behaviour, such as proliferation and cell fate specification. The β-amyloid precursor protein (APP) of Alzheimer's disease (AD) may play an important role in neural stem cell proliferation and differentiation. Our recent work shows that in vitro, APP stimulates neural stem or progenitor cell proliferation and neuronal differentiation. The effect on proliferation is mediated by an autocrine factor that we have identified as cystatin C. As cystatin C expression is also reported to inhibit the development of amyloid pathology in APP transgenic mice, our finding has implications for the possible use of cystatin C for the therapy of AD.
Collapse
Affiliation(s)
- David H Small
- Menzies Research Institute Tasmania and School of Medicine, University of Tasmania, Hobart, Tas., Australia
| | | | | | | | | | | |
Collapse
|
176
|
Turnover of amyloid precursor protein family members determines their nuclear signaling capability. PLoS One 2013; 8:e69363. [PMID: 23874953 PMCID: PMC3715505 DOI: 10.1371/journal.pone.0069363] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 06/07/2013] [Indexed: 12/20/2022] Open
Abstract
The amyloid precursor protein (APP) as well as its homologues, APP-like protein 1 and 2 (APLP1 and APLP2), are cleaved by α-, β-, and γ-secretases, resulting in the release of their intracellular domains (ICDs). We have shown that the APP intracellular domain (AICD) is transported to the nucleus by Fe65 where they jointly bind the histone acetyltransferase Tip60 and localize to spherical nuclear complexes (AFT complexes), which are thought to be sites of transcription. We have now analyzed the subcellular localization and turnover of the APP family members. Similarly to AICD, the ICD of APLP2 localizes to spherical nuclear complexes together with Fe65 and Tip60. In contrast, the ICD of APLP1, despite binding to Fe65, does not translocate to the nucleus. In addition, APLP1 predominantly localizes to the plasma membrane, whereas APP and APLP2 are detected in vesicular structures. APLP1 also demonstrates a much slower turnover of the full-length protein compared to APP and APLP2. We further show that the ICDs of all APP family members are degraded by the proteasome and that the N-terminal amino acids of ICDs determine ICD degradation rate. Together, our results suggest that different nuclear signaling capabilities of APP family members are due to different rates of full-length protein processing and ICD proteasomal degradation. Our results provide evidence in support of a common nuclear signaling function for APP and APLP2 that is absent in APLP1, but suggest that APLP1 has a regulatory role in the nuclear translocation of APP family ICDs due to the sequestration of Fe65.
Collapse
|
177
|
Abramsson A, Kettunen P, Banote RK, Lott E, Li M, Arner A, Zetterberg H. The zebrafish amyloid precursor protein-b is required for motor neuron guidance and synapse formation. Dev Biol 2013; 381:377-88. [PMID: 23850871 DOI: 10.1016/j.ydbio.2013.06.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 06/26/2013] [Accepted: 06/27/2013] [Indexed: 11/26/2022]
Abstract
The amyloid precursor protein (APP) is a transmembrane protein mostly recognized for its association with Alzheimer's disease. The physiological function of APP is still not completely understood much because of the redundancy between genes in the APP family. In this study we have used zebrafish to study the physiological function of the zebrafish APP homologue, appb, during development. We show that appb is expressed in post-mitotic neurons in the spinal cord. Knockdown of appb by 50-60% results in a behavioral phenotype with increased spontaneous coiling and prolonged touch-induced activity. The spinal cord motor neurons in these embryos show defective formation and axonal outgrowth patterning. Reduction in Appb also results in patterning defects and changed density of pre- and post-synapses in the neuromuscular junctions. Together, our data show that development of functional locomotion in zebrafish depends on a critical role of Appb in the patterning of motor neurons and neuromuscular junctions.
Collapse
Affiliation(s)
- Alexandra Abramsson
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, S-41345 Gothenburg, Sweden.
| | | | | | | | | | | | | |
Collapse
|
178
|
Abstract
Biochemical and genetic evidence establishes a central role of the amyloid precursor protein (APP) in Alzheimer disease (AD) pathogenesis. Biochemically, deposition of the β-amyloid (Aβ) peptides produced from proteolytic processing of APP forms the defining pathological hallmark of AD; genetically, both point mutations and duplications of wild-type APP are linked to a subset of early onset of familial AD (FAD) and cerebral amyloid angiopathy. As such, the biological functions of APP and its processing products have been the subject of intense investigation, and the past 20+ years of research have met with both excitement and challenges. This article will review the current understanding of the physiological functions of APP in the context of APP family members.
Collapse
Affiliation(s)
- Ulrike C Müller
- Institute for Pharmacy and Molecular Biotechnology, University of Heidelberg, D-69120 Heidelberg, Germany.
| | | |
Collapse
|
179
|
Abstract
Amyloid-β peptide (Aβ) is considered a key protein in the pathogenesis of Alzheimer's disease (AD) because of its neurotoxicity and capacity to form characteristic insoluble deposits known as senile plaques. Aβ derives from amyloid-β protein precursor (AβPP), whose proteolytic processing generates several fragments including Aβ peptides of various lengths. The normal function of AβPP and its fragments remains poorly understood. While some fragments have been suggested to have a function in normal physiological cellular processes, Aβ has been widely considered as a "garbage" fragment that becomes toxic when it accumulates in the brain, resulting in impaired synaptic function and memory. Aβ is produced and released physiologically in the healthy brain during neuronal activity. In the last 10 years, we have been investigating whether Aβ plays a physiological role in the brain. We first demonstrated that picomolar concentrations of a human Aβ42 preparation enhanced synaptic plasticity and memory in mice. Next, we investigated the role of endogenous Aβ in healthy murine brains and found that treatment with a specific antirodent Aβ antibody and an siRNA against murine AβPP impaired synaptic plasticity and memory. The concurrent addition of human Aβ42 rescued these deficits, suggesting that in the healthy brain, physiological Aβ concentrations are necessary for normal synaptic plasticity and memory to occur. Furthermore, the effect of both exogenous and endogenous Aβ was seen to be mediated by modulation of neurotransmitter release and α7-nicotinic receptors. These findings need to be taken into consideration when designing novel therapeutic strategies for AD.
Collapse
Affiliation(s)
- Daniela Puzzo
- Department of Bio-Medical Sciences, Section of Physiology, University of Catania, Catania, Italy
| | | |
Collapse
|
180
|
Affiliation(s)
- Amy R. Wyatt
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia;
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Justin J. Yerbury
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia;
| | - Heath Ecroyd
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia;
| | - Mark R. Wilson
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia;
| |
Collapse
|
181
|
Amyloid β precursor protein as a molecular target for amyloid β--induced neuronal degeneration in Alzheimer's disease. Neurobiol Aging 2013; 34:2525-37. [PMID: 23714735 DOI: 10.1016/j.neurobiolaging.2013.04.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/17/2013] [Accepted: 04/20/2013] [Indexed: 11/23/2022]
Abstract
A role of amyloid β (Aβ) peptide aggregation and deposition in Alzheimer's disease (AD) pathogenesis is widely accepted. Significantly, abnormalities induced by aggregated Aβ have been linked to synaptic and neuritic degeneration, consistent with the "dying-back" pattern of degeneration that characterizes neurons affected in AD. However, molecular mechanisms underlying the toxic effect of aggregated Aβ remain elusive. In the last 2 decades, a variety of aggregated Aβ species have been identified and their toxic properties demonstrated in diverse experimental systems. Concurrently, specific Aβ assemblies have been shown to interact and misregulate a growing number of molecular effectors with diverse physiological functions. Such pleiotropic effects of aggregated Aβ posit a mayor challenge for the identification of the most cardinal Aβ effectors relevant to AD pathology. In this review, we discuss recent experimental evidence implicating amyloid β precursor protein (APP) as a molecular target for toxic Aβ assemblies. Based on a significant body of pathologic observations and experimental evidence, we propose a novel pathologic feed-forward mechanism linking Aβ aggregation to abnormalities in APP processing and function, which in turn would trigger the progressive loss of neuronal connectivity observed early in AD.
Collapse
|
182
|
Shariati SAM, De Strooper B. Redundancy and divergence in the amyloid precursor protein family. FEBS Lett 2013; 587:2036-45. [PMID: 23707420 DOI: 10.1016/j.febslet.2013.05.026] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 05/08/2013] [Indexed: 11/30/2022]
Abstract
Gene duplication provides genetic material required for functional diversification. An interesting example is the amyloid precursor protein (APP) protein family. The APP gene family has experienced both expansion and contraction during evolution. The three mammalian members have been studied quite extensively in combined knock out models. The underlying assumption is that APP, amyloid precursor like protein 1 and 2 (APLP1, APLP2) are functionally redundant. This assumption is primarily supported by the similarities in biochemical processing of APP and APLPs and on the fact that the different APP genes appear to genetically interact at the level of the phenotype in combined knockout mice. However, unique features in each member of the APP family possibly contribute to specification of their function. In the current review, we discuss the evolution and the biology of the APP protein family with special attention to the distinct properties of each homologue. We propose that the functions of APP, APLP1 and APLP2 have diverged after duplication to contribute distinctly to different neuronal events. Our analysis reveals that APLP2 is significantly diverged from APP and APLP1.
Collapse
Affiliation(s)
- S Ali M Shariati
- KU Leuven, Center for Human Genetics and Leuven Institute for Neurodegenerative Diseases (LIND), 3000 Leuven, Belgium
| | | |
Collapse
|
183
|
Liraz O, Boehm-Cagan A, Michaelson DM. ApoE4 induces Aβ42, tau, and neuronal pathology in the hippocampus of young targeted replacement apoE4 mice. Mol Neurodegener 2013; 8:16. [PMID: 23684315 PMCID: PMC3659080 DOI: 10.1186/1750-1326-8-16] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 04/18/2013] [Indexed: 12/26/2022] Open
Abstract
Background Recent findings suggest that the pathological effects of apoE4, the most prevalent genetic risk factor for Alzheimer’s disease (AD), start many years before the onset of the disease and are already detectable at a young age. In the present study we investigated the extent to which such pathological and cognitive impairments also occur in young apoE4 mice. Results This study revealed that the levels of the presynaptic glutamatergic vesicular transporter, VGlut, in the CA3, CA1, and DG hippocampal subfields were lower in hippocampal neurons of young (4-month-old) apoE4-targeted replacement mice than in those of the apoE3 mice. In contrast, the corresponding inhibitory GABAergic nerve terminals and perikarya were not affected by apoE4. This synaptic effect was associated with hyperphosphorylation of tau in these neurons. In addition, apoE4 increased the accumulation of neuronal Aβ42 and induced mitochondrial changes, both of which were specifically pronounced in CA3 neurons. Spatial navigation behavioral studies revealed that these hippocampal pathological effects of apoE4 are associated with corresponding behavioral impairments. Time-course studies revealed that the effects of apoE4 on tau hyperphosphorylation and the mitochondria were already apparent at the age of 1 month and that the apoE4-driven accumulation of neuronal Aβ and reduced VGlut levels evolve later and are apparent at the age of 2–4 months. Furthermore, the levels of tau phosphorylation decrease in apoE3 mice and increase in apoE4 mice between 1 and 4 months, whereas the levels of Aβ42 decrease in apoE3 mice and are not affected in apoE4 mice over the same time period. Conclusions These findings show that apoE4 stimulates the accumulation of Aβ42 and hyperphosphorylated tau and reduces the levels of VGlut in hippocampal neurons of young apoE4-targeted replacement mice and that these neurochemical effects are associated with cognitive impairments. This model is not associated with hypothesis-driven mechanistic manipulations and is thus most suitable for unbiased studies of the mechanisms underlying the pathological effects of apoE4.
Collapse
Affiliation(s)
- Ori Liraz
- Department of Neurobiology, The George S, Wise Faculty of Life Sciences, The Sagol School of Neuroscience, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel
| | | | | |
Collapse
|
184
|
Raslan AA, Kee Y. Tackling neurodegenerative diseases: animal models of Alzheimer’s disease and Parkinson’s disease. Genes Genomics 2013. [DOI: 10.1007/s13258-013-0116-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
185
|
Soldano A, Okray Z, Janovska P, Tmejová K, Reynaud E, Claeys A, Yan J, Atak ZK, De Strooper B, Dura JM, Bryja V, Hassan BA. The Drosophila homologue of the amyloid precursor protein is a conserved modulator of Wnt PCP signaling. PLoS Biol 2013; 11:e1001562. [PMID: 23690751 PMCID: PMC3653798 DOI: 10.1371/journal.pbio.1001562] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 04/02/2013] [Indexed: 01/23/2023] Open
Abstract
Wnt Planar Cell Polarity (PCP) signaling is a universal regulator of polarity in epithelial cells, but it regulates axon outgrowth in neurons, suggesting the existence of axonal modulators of Wnt-PCP activity. The Amyloid precursor proteins (APPs) are intensely investigated because of their link to Alzheimer's disease (AD). APP's in vivo function in the brain and the mechanisms underlying it remain unclear and controversial. Drosophila possesses a single APP homologue called APP Like, or APPL. APPL is expressed in all neurons throughout development, but has no established function in neuronal development. We therefore investigated the role of Drosophila APPL during brain development. We find that APPL is involved in the development of the Mushroom Body αβ neurons and, in particular, is required cell-autonomously for the β-axons and non-cell autonomously for the α-axons growth. Moreover, we find that APPL is a modulator of the Wnt-PCP pathway required for axonal outgrowth, but not cell polarity. Molecularly, both human APP and fly APPL form complexes with PCP receptors, thus suggesting that APPs are part of the membrane protein complex upstream of PCP signaling. Moreover, we show that APPL regulates PCP pathway activation by modulating the phosphorylation of the Wnt adaptor protein Dishevelled (Dsh) by Abelson kinase (Abl). Taken together our data suggest that APPL is the first example of a modulator of the Wnt-PCP pathway specifically required for axon outgrowth.
Collapse
Affiliation(s)
- Alessia Soldano
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
| | - Zeynep Okray
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
| | - Pavlina Janovska
- Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Kateřina Tmejová
- Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Elodie Reynaud
- Institut de Génétique Humaine/Centre National de la Recherche Scientifique UPR1142, Montpellier, France
- Laboratoire Neurogénétique et Mémoire, Département Génétique et Développement, Montpellier, France
| | - Annelies Claeys
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Jiekun Yan
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Zeynep Kalender Atak
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Bart De Strooper
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
| | - Jean-Maurice Dura
- Institut de Génétique Humaine/Centre National de la Recherche Scientifique UPR1142, Montpellier, France
- Laboratoire Neurogénétique et Mémoire, Département Génétique et Développement, Montpellier, France
| | - Vítězslav Bryja
- Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
- Institute of Biophysics of the Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Bassem A. Hassan
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
| |
Collapse
|
186
|
Sosa LJ, Bergman J, Estrada-Bernal A, Glorioso TJ, Kittelson JM, Pfenninger KH. Amyloid precursor protein is an autonomous growth cone adhesion molecule engaged in contact guidance. PLoS One 2013; 8:e64521. [PMID: 23691241 PMCID: PMC3653867 DOI: 10.1371/journal.pone.0064521] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 04/15/2013] [Indexed: 12/22/2022] Open
Abstract
Amyloid precursor protein (APP), a transmembrane glycoprotein, is well known for its involvement in the pathogenesis of Alzheimer disease of the aging brain, but its normal function is unclear. APP is a prominent component of the adult as well as the developing brain. It is enriched in axonal growth cones (GCs) and has been implicated in cell adhesion and motility. We tested the hypothesis that APP is an extracellular matrix adhesion molecule in experiments that isolated the function of APP from that of well-established adhesion molecules. To this end we plated wild-type, APP-, or β1-integrin (Itgb1)- misexpressing mouse hippocampal neurons on matrices of either laminin, recombinant L1, or synthetic peptides binding specifically to Itgb1 s or APP. We measured GC adhesion, initial axonal outgrowth, and substrate preference on alternating matrix stripes and made the following observations: Substrates of APP-binding peptide alone sustain neurite outgrowth; APP dosage controls GC adhesion to laminin and APP-binding peptide as well as axonal outgrowth in Itgb1- independent manner; and APP directs GCs in contact guidance assays. It follows that APP is an independently operating cell adhesion molecule that affects the GC's phenotype on APP-binding matrices including laminin, and that it is likely to affect axon pathfinding in vivo.
Collapse
Affiliation(s)
- Lucas J. Sosa
- Department of Pediatrics and Colorado Intellectual and Developmental Disabilities Research Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Jared Bergman
- Department of Pediatrics and Colorado Intellectual and Developmental Disabilities Research Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Adriana Estrada-Bernal
- Department of Pediatrics and Colorado Intellectual and Developmental Disabilities Research Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Thomas J. Glorioso
- Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Anschutz Medical Center, Aurora, Colorado, United States of America
| | - John M. Kittelson
- Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Anschutz Medical Center, Aurora, Colorado, United States of America
| | - Karl H. Pfenninger
- Department of Pediatrics and Colorado Intellectual and Developmental Disabilities Research Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail:
| |
Collapse
|
187
|
Hippocampal network oscillations in APP/APLP2-deficient mice. PLoS One 2013; 8:e61198. [PMID: 23585881 PMCID: PMC3621758 DOI: 10.1371/journal.pone.0061198] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/08/2013] [Indexed: 11/19/2022] Open
Abstract
The physiological function of amyloid precursor protein (APP) and its two homologues APP-like protein 1 (APLP1) and 2 (APLP2) is largely unknown. Previous work suggests that lack of APP or APLP2 impairs synaptic plasticity and spatial learning. There is, however, almost no data on the role of APP or APLP at the network level which forms a critical interface between cellular functions and behavior. We have therefore investigated memory-related synaptic and network functions in hippocampal slices from three lines of transgenic mice: APPsα-KI (mice expressing extracellular fragment of APP, corresponding to the secreted APPsα ectodomain), APLP2-KO, and combined APPsα-KI/APLP2-KO (APPsα-DM for “double mutants”). We analyzed two prominent patterns of network activity, gamma oscillations and sharp-wave ripple complexes (SPW-R). Both patterns were generally preserved in all strains. We find, however, a significantly reduced frequency of gamma oscillations in CA3 of APLP2-KO mice in comparison to APPsα-KI and WT mice. Network activity, basic synaptic transmission and short-term plasticity were unaltered in the combined mutants (APPsα-DM) which showed, however, reduced long-term potentiation (LTP). Together, our data indicate that APLP2 and the intracellular domain of APP are not essential for coherent activity patterns in the hippocampus, but have subtle effects on synaptic plasticity and fine-tuning of network oscillations.
Collapse
|
188
|
Spike bursts increase amyloid-β 40/42 ratio by inducing a presenilin-1 conformational change. Nat Neurosci 2013; 16:587-95. [PMID: 23563578 DOI: 10.1038/nn.3376] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 02/26/2013] [Indexed: 11/08/2022]
|
189
|
Dysregulation of hypoxia-inducible factor by presenilin/γ-secretase loss-of-function mutations. J Neurosci 2013; 33:1915-26. [PMID: 23365231 DOI: 10.1523/jneurosci.3402-12.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Presenilin (PSEN) 1 and 2 are the catalytic components of the γ-secretase complex, which cleaves a variety of proteins, including the amyloid precursor protein (APP). Proteolysis of APP leads to the formation of the APP intracellular domain (AICD) and amyloid β that is crucially involved in the pathogenesis of Alzheimer's disease. Prolyl-4-hydroxylase-domain (PHD) proteins regulate the hypoxia-inducible factors (HIFs), the master regulators of the hypoxic response. We previously identified the FK506 binding protein 38 (FKBP38) as a negative regulator of PHD2. Genetic ablation of PSEN1/2 has been shown to increase FKBP38 protein levels. Therefore, we investigated the role of PSEN1/2 in the oxygen sensing pathway using a variety of genetically modified cell and mouse lines. Increased FKBP38 protein levels and decreased PHD2 protein levels were found in PSEN1/2-deficient mouse embryonic fibroblasts and in the cortex of forebrain-specific PSEN1/2 conditional double knock-out mice. Hypoxic HIF-1α protein accumulation and transcriptional activity were decreased, despite reduced PHD2 protein levels. Proteolytic γ-secretase function of PSEN1/2 was needed for proper HIF activation. Intriguingly, PSEN1/2 mutations identified in Alzheimer patients differentially affected the hypoxic response, involving the generation of AICD. Together, our results suggest a direct role for PSEN in the regulation of the oxygen sensing pathway via the APP/AICD cleavage cascade.
Collapse
|
190
|
Duce JA, Ayton S, Miller AA, Tsatsanis A, Lam LQ, Leone L, Corbin JE, Butzkueven H, Kilpatrick TJ, Rogers JT, Barnham KJ, Finkelstein DI, Bush AI. Amine oxidase activity of β-amyloid precursor protein modulates systemic and local catecholamine levels. Mol Psychiatry 2013; 18:245-54. [PMID: 22212595 DOI: 10.1038/mp.2011.168] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The catecholamines dopamine (DA), norepinephrine (NE) and epinephrine (E) are neurotransmitters and hormones that mediate stress responses in tissues and plasma. The expression of β-amyloid precursor protein (APP) is responsive to stress and is high in tissues rich in catecholamines. We recently reported that APP is a ferroxidase, subsuming, in neurons and other cells, the iron-export activity that ceruloplasmin mediates in glia. Here we report that, like ceruloplasmin, APP also oxidizes synthetic amines and catecholamines catalytically (K(m) NE=0.27 mM), through a site encompassing its ferroxidase motif and selectively inhibited by zinc. Accordingly, APP knockout mice have significantly higher levels of DA, NE and E in brain, plasma and select tissues. Consistent with this, these animals have increased resting heart rate and systolic blood pressure as well as suppressed prolactin and lymphocyte levels. These findings support a role for APP in extracellular catecholaminergic clearance.
Collapse
Affiliation(s)
- J A Duce
- The Mental Health Research Institute, The University of Melbourne, Parkville, VIC, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
191
|
Teich AF, Patel M, Arancio O. A reliable way to detect endogenous murine β-amyloid. PLoS One 2013; 8:e55647. [PMID: 23383341 PMCID: PMC3562188 DOI: 10.1371/journal.pone.0055647] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 12/31/2012] [Indexed: 01/09/2023] Open
Abstract
Unraveling the normal physiologic role of β-amyloid is likely crucial to understanding the pathogenesis of Alzheimer's disease. However, progress on this question is currently limited by the high background of many ELISAs for murine β-amyloid. Here, we examine the background signal of several murine β-amyloid ELISAs, and conclude that the majority of the background is from non-APP derived proteins. Most importantly, we identify ELISAs that eliminate this background signal.
Collapse
Affiliation(s)
- Andrew F Teich
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, New York, United States of America.
| | | | | |
Collapse
|
192
|
Takahashi RH, Capetillo-Zarate E, Lin MT, Milner TA, Gouras GK. Accumulation of intraneuronal β-amyloid 42 peptides is associated with early changes in microtubule-associated protein 2 in neurites and synapses. PLoS One 2013; 8:e51965. [PMID: 23372648 PMCID: PMC3553177 DOI: 10.1371/journal.pone.0051965] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 11/09/2012] [Indexed: 11/19/2022] Open
Abstract
Pathologic aggregation of β-amyloid (Aβ) peptide and the axonal microtubule-associated protein tau protein are hallmarks of Alzheimer's disease (AD). Evidence supports that Aβ peptide accumulation precedes microtubule-related pathology, although the link between Aβ and tau remains unclear. We previously provided evidence for early co-localization of Aβ42 peptides and hyperphosphorylated tau within postsynaptic terminals of CA1 dendrites in the hippocampus of AD transgenic mice. Here, we explore the relation between Aβ peptide accumulation and the dendritic, microtubule-associated protein 2 (MAP2) in the well-characterized amyloid precursor protein Swedish mutant transgenic mouse (Tg2576). We provide evidence that localized intraneuronal accumulation of Aβ42 peptides is spatially associated with reductions of MAP2 in dendrites and postsynaptic compartments of Tg2576 mice at early ages. Our data support that reduction in MAP2 begins at sites of Aβ42 monomer and low molecular weight oligomer (M/LMW) peptide accumulation. Cumulative evidence suggests that accumulation of M/LMW Aβ42 peptides occurs early, before high molecular weight oligomerization and plaque formation. Since synaptic alteration is the best pathologic correlate of cognitive dysfunction in AD, the spatial association of M/LMW Aβ peptide accumulation with pathology of MAP2 within neuronal processes and synaptic compartments early in the disease process reinforces the importance of intraneuronal Aβ accumulation in AD pathogenesis.
Collapse
Affiliation(s)
- Reisuke H. Takahashi
- Department of Anatomic Pathology, Tokyo Medical University, Tokyo, Japan
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (RHT); (GKG)
| | - Estibaliz Capetillo-Zarate
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York, United States of America
| | - Michael T. Lin
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York, United States of America
| | - Teresa A. Milner
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York, United States of America
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, New York, United States of America
| | - Gunnar K. Gouras
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York, United States of America
- Wallenberg Neuroscience Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail: (RHT); (GKG)
| |
Collapse
|
193
|
Appoptosin is a novel pro-apoptotic protein and mediates cell death in neurodegeneration. J Neurosci 2013; 32:15565-76. [PMID: 23115192 DOI: 10.1523/jneurosci.3668-12.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Apoptosis is an essential cellular process in multiple diseases and a major pathway for neuronal death in neurodegeneration. The detailed signaling events/pathways leading to apoptosis, especially in neurons, require further elucidation. Here we identify a β-amyloid precursor protein (APP)-interacting protein, designated as appoptosin, whose levels are upregulated in brain samples from Alzheimer's disease and infarct patients, and in rodent stroke models, as well as in neurons treated with β-amyloid (Aβ) and glutamate. We further demonstrate that appoptosin induces reactive oxygen species release and intrinsic caspase-dependent apoptosis. The physiological function of appoptosin is to transport/exchange glycine/5-amino-levulinic acid across the mitochondrial membrane for heme synthesis. Downregulation of appoptosin prevents cell death and caspase activation caused by glutamate or Aβ insults. APP modulates appoptosin-mediated apoptosis through interaction with appoptosin. Our study identifies appoptosin as a crucial player in apoptosis and a novel pro-apoptotic protein involved in neuronal cell death, providing a possible new therapeutic target for neurodegenerative disorders.
Collapse
|
194
|
Evin G, Li QX. Platelets and Alzheimer’s disease: Potential of APP as a biomarker. World J Psychiatry 2012; 2:102-13. [PMID: 24175176 PMCID: PMC3782192 DOI: 10.5498/wjp.v2.i6.102] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 07/13/2012] [Accepted: 07/23/2012] [Indexed: 02/05/2023] Open
Abstract
Platelets are the first peripheral source of amyloid precursor protein (APP). They possess the proteolytic machinery to produce Aβ and fragments similar to those produced in neurons, and thus offer an ex-vivo model to study APP processing and changes associated with Alzheimer’s disease (AD). Platelet process APP mostly through the α-secretase pathway to release soluble APP (sAPP). They produce small amounts of Aβ, predominantly Aβ40 over Aβ42. sAPP and Aβ are stored in α-granules and are released upon platelet activation by thrombin and collagen, and agents inducing platelet degranulation. A small proportion of full-length APP is present at the platelet surface and this increases by 3-fold upon platelet activation. Immunoblotting of platelet lysates detects APP as isoforms of 130 kDa and 106-110 kDa. The ratio of these of APP isoforms is significantly lower in patients with AD and mild cognitive impairment (MCI) than in healthy controls. This ratio follows a decrease that parallels cognitive decline and can predict conversion from MCI to AD. Alterations in the levels of α-secretase ADAM10 and in the enzymatic activities of α- and β-secretase observed in platelets of patients with AD are consistent with increased processing through the amyloidogenic pathway. β-APP cleaving enzyme activity is increased by 24% in platelet membranes of patients with MCI and by 17% in those with AD. Reports of changes in platelet APP expression with MCI and AD have been promising so far and merit further investigation as the search for blood biomarkers in AD, in particular at the prodromal stage, remains a priority and a challenge.
Collapse
Affiliation(s)
- Geneviève Evin
- Geneviève Evin, Qiao-Xin Li, Department of Pathology and Mental Health Research Institute, The University of Melbourne, Parkville 3010, Australia
| | | |
Collapse
|
195
|
Abstract
Compelling evidence from in vivo model systems within the past decade shows that the APP family of proteins is important for synaptic development and function in the central and peripheral nervous systems. The synaptic role promises to be complex and multifaceted for several reasons. The three family members have overlapping and redundant functions in mammals. They have both adhesive and signaling properties and may, in principle, act as both ligands and receptors. Moreover, they bind a multitude of synapse-specific proteins, and we predict that additional interacting protein partners will be discovered. Transgenic mice with modified or abolished expression of APP and APLPs have synaptic defects that are readily apparent. Studies of the neuromuscular junction (NMJ) in these transgenic mice have revealed molecular and functional deficits in neurotransmitter release, in organization of the postsynaptic receptors, and in coordinated intercellular development. The results summarized here from invertebrate and vertebrate systems confirm that the NMJ with its accessibility, large size, and homogeneity provides a model synapse for identifying and analyzing molecular pathways of APP actions.
Collapse
|
196
|
Billnitzer AJ, Barskaya I, Yin C, Perez RG. APP independent and dependent effects on neurite outgrowth are modulated by the receptor associated protein (RAP). J Neurochem 2012; 124:123-32. [PMID: 23061396 DOI: 10.1111/jnc.12051] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 09/24/2012] [Accepted: 10/08/2012] [Indexed: 11/30/2022]
Abstract
Amyloid precursor protein (APP) and its secreted form, sAPP, contribute to the development of neurons in hippocampus, a brain region critical for learning and memory. Full-length APP binds the low-density lipoprotein receptor-related protein (LRP), which stimulates APP endocytosis. LRP also contributes to neurite growth. Furthermore, the receptor associated protein (RAP) binds LRP in a manner that blocks APP-LRP interactions. To elucidate APP contributions to neurite growth for full-length APP and sAPP, we cultured wild type (WT) and APP knockout (KO) neurons in sAPPα and/or RAP and measured neurite outgrowth at 1 day in vitro. Our data reveal that WT neurons had less axonal outgrowth including less axon branching. RAP treatment potentiated the inhibitory effects of APP. KO neurons had significantly more outgrowth and branching, especially in response to RAP, effects which were also associated with ERK2 activation. Our results affirm a major inhibitory role by full-length APP on all aspects of axonal and dendritic outgrowth, and show that RAP-LRP binding stimulated axon growth independently of APP. These findings support a major role for APP as an inhibitor of neurite growth and reveal novel signaling functions for LRP that may be disrupted by Alzheimer's pathology or therapies aimed at APP processing.
Collapse
Affiliation(s)
- Andrew J Billnitzer
- Center of Excellence in Neurosciences, Department of Biomedical Sciences, Texas Tech University Health Sciences Center, Paul L. Foster School of Medicine, El Paso, TX 79905, USA
| | | | | | | |
Collapse
|
197
|
Kiba T. Relationships between ventromedial hypothalamic lesions and the expressions of neuron-related genes in visceral organs. Neurosci Res 2012; 74:1-6. [DOI: 10.1016/j.neures.2012.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 07/02/2012] [Accepted: 07/04/2012] [Indexed: 10/28/2022]
|
198
|
Koike MA, Lin AJ, Pham J, Nguyen E, Yeh JJ, Rahimian R, Tromberg BJ, Choi B, Green KN, LaFerla FM. APP knockout mice experience acute mortality as the result of ischemia. PLoS One 2012; 7:e42665. [PMID: 22912719 PMCID: PMC3415410 DOI: 10.1371/journal.pone.0042665] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 07/10/2012] [Indexed: 01/26/2023] Open
Abstract
The incidence of Alzheimer’s disease increases in people who have had an ischemic episode. Furthermore, APP expression is increased following ischemic or hypoxic conditions, as is the production of the Aβ peptide. To address the question of why APP and Aβ are increased in hypoxic and ischemic conditions we induced an ischemic episode in APP knockout mice (APP−/−) and BACE1 knockout mice (BACE−/−). We find that both APP−/− and BACE−/− mice have a dramatically increased risk of mortality as a result of cerebral ischemia. Furthermore, APP knockout mice have reduced cerebral blood flow in response to hypoxia, while wild-type mice maintain or increase cerebral blood flow to the same conditions. The transcription factor, serum response factor (SRF), and calcium-binding molecule, calsequestrin, both involved in vascular regulation, are significantly altered in the brains of APP−/− mice compared to wild type controls. These results show that APP regulates cerebral blood flow in response to hypoxia, and that it, and its cleavage fragments, are crucial for rapid adaptation to ischemic conditions.
Collapse
Affiliation(s)
- Maya A. Koike
- Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, California, United States of America
| | - Alexander J. Lin
- Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, California, United States of America
- Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, Irvine, California, United States of America
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
| | - Jonathan Pham
- Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, Irvine, California, United States of America
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
| | - Elaine Nguyen
- Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, Irvine, California, United States of America
| | - James J. Yeh
- Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, Irvine, California, United States of America
| | - Rombod Rahimian
- Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, Irvine, California, United States of America
| | - Bruce J. Tromberg
- Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, Irvine, California, United States of America
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
| | - Bernard Choi
- Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, Irvine, California, United States of America
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
- Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California Irvine, Irvine, California, United States of America
| | - Kim N. Green
- Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, California, United States of America
- * E-mail: (FML); (KNG)
| | - Frank M. LaFerla
- Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, California, United States of America
- * E-mail: (FML); (KNG)
| |
Collapse
|
199
|
Gulati V, Wallace R. Rafts, Nanoparticles and Neural Disease. NANOMATERIALS (BASEL, SWITZERLAND) 2012; 2:217-250. [PMID: 28348305 PMCID: PMC5304588 DOI: 10.3390/nano2030217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 07/19/2012] [Accepted: 07/20/2012] [Indexed: 11/17/2022]
Abstract
This review examines the role of membrane rafts in neural disease as a rationale for drug targeting utilizing lipid-based nanoparticles. The article begins with an overview of methodological issues involving the existence, sizes, and lifetimes of rafts, and then examines raft function in the etiologies of three major neural diseases-epilepsy, Parkinson's disease, and Alzheimer's disease-selected as promising candidates for raft-based therapeutics. Raft-targeting drug delivery systems involving liposomes and solid lipid nanoparticles are then examined in detail.
Collapse
Affiliation(s)
- Vishal Gulati
- Ross University School of Medicine, Miami Beach Community Health Center, 11645 Biscayne Boulevard, North Miami, FL 33181, USA.
| | - Ron Wallace
- Department of Anthropology, University of Central Florida, Orlando, FL 32816, USA.
| |
Collapse
|
200
|
Tyan SH, Shih AYJ, Walsh JJ, Maruyama H, Sarsoza F, Ku L, Eggert S, Hof PR, Koo EH, Dickstein DL. Amyloid precursor protein (APP) regulates synaptic structure and function. Mol Cell Neurosci 2012; 51:43-52. [PMID: 22884903 DOI: 10.1016/j.mcn.2012.07.009] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 05/25/2012] [Accepted: 07/26/2012] [Indexed: 11/16/2022] Open
Abstract
The amyloid precursor protein (APP) plays a critical role in Alzheimer's disease (AD) pathogenesis. APP is proteolytically cleaved by β- and γ-secretases to generate the amyloid β-protein (Aβ), the core protein component of senile plaques in AD. It is also cleaved by α-secretase to release the large soluble APP (sAPP) luminal domain that has been shown to exhibit trophic properties. Increasing evidence points to the development of synaptic deficits and dendritic spine loss prior to deposition of amyloid in transgenic mouse models that overexpress APP and Aβ peptides. The consequence of loss of APP, however, is unsettled. In this study, we investigated whether APP itself plays a role in regulating synaptic structure and function using an APP knock-out (APP-/-) mouse model. We examined dendritic spines in primary cultures of hippocampal neurons and CA1 neurons of hippocampus from APP-/- mice. In the cultured neurons, there was a significant decrease (~35%) in spine density in neurons derived from APP-/- mice compared to littermate control neurons that were partially restored with sAPPα-conditioned medium. In APP-/- mice in vivo, spine numbers were also significantly reduced but by a smaller magnitude (~15%). Furthermore, apical dendritic length and dendritic arborization were markedly diminished in hippocampal neurons. These abnormalities in neuronal morphology were accompanied by reduction in long-term potentiation. Strikingly, all these changes in vivo were only seen in mice that were 12-15 months in age but not in younger animals. We propose that APP, specifically sAPP, is necessary for the maintenance of dendritic integrity in the hippocampus in an age-associated manner. Finally, these age-related changes may contribute to AD pathology independent of Aβ-mediated synaptic toxicity.
Collapse
Affiliation(s)
- Sheue-Houy Tyan
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|