151
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Abstract
Reelin coordinates the movements of neurons during brain development by signaling through the Dab1 adaptor and Src family tyrosine kinases. Experiments with cultured neurons have shown that when Dab1 is phosphorylated on tyrosine, it activates Akt and provides a scaffold for assembling signaling complexes, including the paralogous Crk and CrkL adaptors. The roles of Akt and Dab1 complexes during development have been unclear. We have generated two Dab1 alleles, each lacking two out of the four putative tyrosine phosphorylation sites. Neither allele supports normal brain development, but each allele complements the other. Two tyrosines are required for Reelin to stimulate Dab1 phosphorylation at the other sites, to activate Akt, and to downregulate Dab1 levels. The other two tyrosines are required to stimulate a Crk/CrkL-C3G pathway. The absence of Crk/CrkL binding sites and C3G activation causes an unusual layering phenotype. These results show that Reelin-induced Akt stimulation and Dab1 turnover are not sufficient for normal development and suggest that Dab1 acts both as a kinase switch and as a scaffold for assembling signaling complexes in vivo.
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152
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Hernández F, Avila J. The role of glycogen synthase kinase 3 in the early stages of Alzheimers’ disease. FEBS Lett 2008; 582:3848-54. [DOI: 10.1016/j.febslet.2008.10.026] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 10/17/2008] [Accepted: 10/18/2008] [Indexed: 12/14/2022]
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153
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Interleukin-18 increases expression of kinases involved in tau phosphorylation in SH-SY5Y neuroblastoma cells. J Neuroimmunol 2008; 205:86-93. [PMID: 18947885 DOI: 10.1016/j.jneuroim.2008.09.012] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 09/02/2008] [Accepted: 09/15/2008] [Indexed: 12/29/2022]
Abstract
Inflammatory cytokines, produced mainly by activated microglia in the brain, can enhance neuronal degeneration and the amyloid-beta-plaque production involved in Alzheimer's disease (AD). We previously demonstrated that the expression of the pro-inflammatory cytokine interleukin-18 (IL-18) colocalizes with plaques and hyperphoshorylated tau containing neurons in AD patients. Here we exposed neuron-like, differentiated SH-SY5Y neuroblastomas to IL-18 and observed that the protein levels of p35, Cdk5, GSK-3beta, and Ser15-phosphorylated p53 increased during 6 h-24 h. Tau phosphorylation and expression of cyclin G1, involved in neuronal regeneration, increased at 72 h. In vivo, over-expression of IL-18 may induce hyperphosphorylation of tau and induce cell cycle activators.
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154
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Keilani S, Sugaya K. Reelin induces a radial glial phenotype in human neural progenitor cells by activation of Notch-1. BMC DEVELOPMENTAL BIOLOGY 2008; 8:69. [PMID: 18593473 PMCID: PMC2447831 DOI: 10.1186/1471-213x-8-69] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 07/01/2008] [Indexed: 11/12/2022]
Abstract
Background Reelin and Notch-1 signaling pathways have been recently found to be necessary to induce the expression of brain lipid binding protein (BLBP) and to promote the process extension and the maturation of the neuronal progenitors, the radial glial cells. In this study, we report the cross talk between these two pathways. Results Both in vitro Reelin treatment and overexpression of Notch-1 intracellular domain (NICD) induced BLBP expression and a radial glial phenotype in an immortalized human neural progenitor (HNP) cell line, isolated from the cortex of 14 weeks old fetus. Reelin treatment increased the level of NICD, indicating that Reelin signaling directly activates Notch-1. In addition, reducing NICD release, by inhibiting γ-secretase activity, inhibited the Reelin-induced radial glial phenotype in human neural progenitor cells. Furthermore, we found that Dab-1, an adaptor protein downstream of Reelin, was co-immunoprecipitated with Notch-1 and NICD. Conclusion These data indicate that Reelin signaling induces BLBP expression and a radial glial phenotype in human neural progenitor cells via the activation of Notch-1. This study suggest that Reelin signaling may act to fine tune Notch-1 activation to favor the induction of a radial glial phenotype prenataly and would thus offer an insight into how Notch-1 signaling leads to different cellular fates at different developmental stages.
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Affiliation(s)
- Serene Keilani
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816-2364, USA.
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155
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Regulated proteolysis of APP and ApoE receptors. Mol Neurobiol 2008; 37:64-72. [PMID: 18415033 DOI: 10.1007/s12035-008-8017-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 03/24/2008] [Indexed: 10/22/2022]
Abstract
The beta-amyloid precursor protein (APP) shares intracellular and extracellular-binding partners with the family of receptors for apolipoprotein E (apoE). Binding of APP and apoE receptors to specific extracellular matrix proteins (F-spondin and Reelin) promotes their presence on the cell surface and influences whether they will interact with specific cytoplasmic adaptor proteins. Cleavage of APP and apoE receptors at the cell surface occurs by alpha-secretase activities; thus, the processing of these proteins can be regulated by their trafficking either to or from the cell surface. Their cleavages can also be regulated by tissue inhibitor of metalloproteinase-3 (TIMP-3), a metalloprotease inhibitor in the extracellular matrix. ApoE receptors have functions in neuronal migration during development and in proper synaptic function in the adult. Thus, the functions of apoE receptors and by analogy of APP will be modified by the various extracellular and intracellular interactions reviewed in this paper.
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156
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Kawauchi T, Hoshino M. Molecular pathways regulating cytoskeletal organization and morphological changes in migrating neurons. Dev Neurosci 2008; 30:36-46. [PMID: 18075253 DOI: 10.1159/000109850] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Accepted: 04/19/2007] [Indexed: 12/14/2022] Open
Abstract
Neuronal migration is a pivotal step for architectural and functional brain development. Migrating neurons exhibit various morphological changes, based on cytoskeletal organization. In addition to many genetic studies revealing the involvement of several cytoskeletal and signaling molecules in cortical neuronal migration (e.g. doublecortin, Lis1, Filamin A, cyclin-dependent kinase 5, Reelin and Dab1), cell biological studies and recently developed techniques, including in utero electroporation, have uncovered detailed functions of these molecules as well as novel molecules, such as Rho family GTPases, focal adhesion kinase, c-jun N-terminal kinase and p27(kip1). In this review, we introduce the molecular pathways underlying cortical neuronal migration and morphological changes, with particular focus on recent findings for the regulatory mechanisms of actin cytoskeleton and microtubules.
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Affiliation(s)
- Takeshi Kawauchi
- Department of Anatomy, Keio University School of Medicine, Tokyo, Japan.
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157
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Jossin Y, Goffinet AM. Reelin signals through phosphatidylinositol 3-kinase and Akt to control cortical development and through mTor to regulate dendritic growth. Mol Cell Biol 2007; 27:7113-24. [PMID: 17698586 PMCID: PMC2168915 DOI: 10.1128/mcb.00928-07] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Reelin is an extracellular matrix protein with various functions during development and in the mature brain. It activates different signaling cascades in target cells, one of which is the phosphatidylinositol 3-kinase (PI3K) pathway, which we investigated further using pathway inhibitors and in vitro brain slice and neuronal cultures. We show that the mTor (mammalian target of rapamycin)-S6K1 (S6 kinase 1) pathway is activated by Reelin and that this depends on Dab1 (Disabled-1) phosphorylation and activation of PI3K and Akt (protein kinase B). PI3K and Akt are required for the effects of Reelin on the organization of the cortical plate, but their downstream partners mTor and glycogen synthase kinase 3beta (GSK3beta) are not. On the other hand, mTor, but not GSK3beta, mediates the effects of Reelin on the growth and branching of dendrites of hippocampal neurons. In addition, PI3K fosters radial migration of cortical neurons through the intermediate zone, an effect that is independent of Reelin and Akt.
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Affiliation(s)
- Yves Jossin
- Université Catholique de Louvain, Center for Neurosciences, Avenue E. Mounier, 73, DENE 7382, B1200 Brussels, Belgium
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158
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Lazarov O, Morfini GA, Pigino G, Gadadhar A, Chen X, Robinson J, Ho H, Brady ST, Sisodia SS. Impairments in fast axonal transport and motor neuron deficits in transgenic mice expressing familial Alzheimer's disease-linked mutant presenilin 1. J Neurosci 2007; 27:7011-20. [PMID: 17596450 PMCID: PMC2801050 DOI: 10.1523/jneurosci.4272-06.2007] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Presenilins (PS) play a central role in gamma-secretase-mediated processing of beta-amyloid precursor protein (APP) and numerous type I transmembrane proteins. Expression of mutant PS1 variants causes familial forms of Alzheimer's disease (FAD). In cultured mammalian cells that express FAD-linked PS1 variants, the intracellular trafficking of several type 1 membrane proteins is altered. We now report that the anterograde fast axonal transport (FAT) of APP and Trk receptors is impaired in the sciatic nerves of transgenic mice expressing two independent FAD-linked PS1 variants. Furthermore, FAD-linked PS1 mice exhibit a significant increase in phosphorylation of the cytoskeletal proteins tau and neurofilaments in the spinal cord. Reductions in FAT and phosphorylation abnormalities correlated with motor neuron functional deficits. Together, our data suggests that defects in anterograde FAT may underlie FAD-linked PS1-mediated neurodegeneration through a mechanism involving impairments in neurotrophin signaling and synaptic dysfunction.
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Affiliation(s)
- Orly Lazarov
- Department of Anatomy and Cell Biology, The University of Illinois at Chicago, Chicago, Illinois 60612, and
| | - Gerardo A. Morfini
- Department of Anatomy and Cell Biology, The University of Illinois at Chicago, Chicago, Illinois 60612, and
| | - Gustavo Pigino
- Department of Anatomy and Cell Biology, The University of Illinois at Chicago, Chicago, Illinois 60612, and
| | - Archana Gadadhar
- Department of Anatomy and Cell Biology, The University of Illinois at Chicago, Chicago, Illinois 60612, and
| | | | - John Robinson
- Neurobiology, The University of Chicago, Chicago, Illinois 60637
| | | | - Scott T. Brady
- Department of Anatomy and Cell Biology, The University of Illinois at Chicago, Chicago, Illinois 60612, and
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159
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Helbecque N, Cottel D, Amouyel P. Low-density lipoprotein receptor-related protein 8 gene polymorphisms and dementia. Neurobiol Aging 2007; 30:266-71. [PMID: 17614163 DOI: 10.1016/j.neurobiolaging.2007.05.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 03/20/2007] [Accepted: 05/29/2007] [Indexed: 12/23/2022]
Abstract
The sole known genetic risk factor for sporadic Alzheimer's disease (AD) is the gene encoding apolipoprotein E (APOE), but the underlying mechanism is still under debate. One hypothesis relies on an interaction between APOE and its receptors. Previous studies have shown association of LDL receptor-related protein (LRP1) with AD and we previously reported a modulation by LRP1 of the risk of AD conferred by the -499A>G promoter polymorphism of the MAPK8IP1, a gene encoding Islet-brain-1 (IB1), the human counterpart of c-Jun NH(2) terminal kinase interacting protein-1 (JIP-1). Here we tested in two independent population samples a possible impact of another receptor for APOE, namely the low-density lipoprotein receptor-related protein 8 (LRP8), on the risk of dementia. Our results did not reveal any direct impact of a LRP8 coding (Arg952Gln) mutation on the risk of AD. However, this polymorphism increased the risk of AD conferred by the MAPK8IP1 G allele.
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160
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Beffert U, Nematollah Farsian F, Masiulis I, Hammer RE, Yoon SO, Giehl KM, Herz J. ApoE receptor 2 controls neuronal survival in the adult brain. Curr Biol 2007; 16:2446-52. [PMID: 17174920 DOI: 10.1016/j.cub.2006.10.029] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 10/06/2006] [Accepted: 10/13/2006] [Indexed: 11/29/2022]
Abstract
A central pathogenic feature of neurodegenerative diseases and neurotrauma is the death of neurons. A mechanistic understanding of the factors and conditions that induce the dysfunction and death of neurons is essential for devising effective treatment strategies against neuronal loss after trauma or during aging. Because Apolipoprotein E (ApoE) is a major risk factor for several neurodegenerative diseases, including Alzheimer's disease , a direct or indirect role of ApoE receptors in the disease process is likely. Here we have used gene targeting in mice to investigate possible roles of ApoE receptors in the regulation of neuronal survival. We demonstrate that a differentially spliced isoform of an ApoE receptor, ApoE receptor 2 (Apoer2), is essential for protection against neuronal cell loss during normal aging. Furthermore, the same splice form selectively promotes neuronal cell death after injury through mechanisms that may involve serine/threonine kinases of the Jun N-terminal kinase (JNK) family. These findings raise the possibility that ApoE and its receptors cooperatively regulate common mechanisms that are essential to neuronal survival in the adult brain.
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Affiliation(s)
- Uwe Beffert
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
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161
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Fayad T, Lefebvre R, Nimpf J, Silversides DW, Lussier JG. Low-Density Lipoprotein Receptor-Related Protein 8 (LRP8) Is Upregulated in Granulosa Cells of Bovine Dominant Follicle: Molecular Characterization and Spatio-Temporal Expression Studies1. Biol Reprod 2007; 76:466-75. [PMID: 17108332 DOI: 10.1095/biolreprod.106.057216] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The low-density lipoprotein (LDL) receptor-related protein 8 (LRP8) is a member of the LDL receptor family that participates in endocytosis and signal transduction. We cloned the full-length bovine LRP8 cDNA in granulosa cells (GC) of the dominant follicle (DF) as well as several LRP8 mRNA splicing variants, including a variant that contains a proline-rich cytoplasmic insert (A759-K817) that is involved in intracellular signaling. Expression of the A759-K817 variant was analyzed in the GC of follicles at different developmental stages: the small follicle (SF; 2-4 mm), the DF at Day 5 (D5) of the estrus cycle, ovulatory follicles (OF) 24 h after hCG injection, and corpora lutea (CL) at D5. RT-PCR analysis showed that expression was predominant in the GC of DF compared to other follicles and CL (P<0.0001), whereas the expression of other related receptors, such as LDLR and VLDLR, did not show differences. Temporal analyses of follicular walls from the OF following hCG treatment revealed a decrease in LRP8 mRNA expression starting 12 h post-hCG treatment (P<0.0001). LRP8 protein was exclusively localized to the GC, with higher levels in the DF than in the SF (P<0.05). RELN mRNA, which encodes an LRP8 ligand, was highly expressed in the theca of the DF as compared to the OF (P<0.004), whereas MAPK8IP1 mRNA, which encodes an LRP8 intracellular interacting partner, is expressed in the GC of the DF. These results demonstrate the differential expression patterns of LRP8, RELN, and MAPK8IP1 mRNAs during final follicular growth and ovulation, and suggest that a RELN/LRP8/MAPK8IP1 paracrine interaction regulates follicular growth.
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Affiliation(s)
- Tania Fayad
- Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 7C6
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162
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Zhang G, Assadi AH, McNeil RS, Beffert U, Wynshaw-Boris A, Herz J, Clark GD, D'Arcangelo G. The Pafah1b complex interacts with the reelin receptor VLDLR. PLoS One 2007; 2:e252. [PMID: 17330141 PMCID: PMC1800349 DOI: 10.1371/journal.pone.0000252] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 01/30/2007] [Indexed: 11/18/2022] Open
Abstract
Reelin is an extracellular protein that directs the organization of cortical structures of the brain through the activation of two receptors, the very low-density lipoprotein receptor (VLDLR) and the apolipoprotein E receptor 2 (ApoER2), and the phosphorylation of Disabled-1 (Dab1). Lis1, the product of the Pafah1b1 gene, is a component of the brain platelet-activating factor acetylhydrolase 1b (Pafah1b) complex, and binds to phosphorylated Dab1 in response to Reelin. Here we investigated the involvement of the whole Pafah1b complex in Reelin signaling and cortical layer formation and found that catalytic subunits of the Pafah1b complex, Pafah1b2 and Pafah1b3, specifically bind to the NPxYL sequence of VLDLR, but not to ApoER2. Compound Pafah1b1+/−;Apoer2−/− mutant mice exhibit a reeler-like phenotype in the forebrain consisting of the inversion of cortical layers and hippocampal disorganization, whereas double Pafah1b1+/−;Vldlr−/− mutants do not. These results suggest that a cross-talk between the Pafah1b complex and Reelin occurs downstream of the VLDLR receptor.
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MESH Headings
- 1-Alkyl-2-acetylglycerophosphocholine Esterase/deficiency
- 1-Alkyl-2-acetylglycerophosphocholine Esterase/genetics
- 1-Alkyl-2-acetylglycerophosphocholine Esterase/metabolism
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- COS Cells
- Catalytic Domain
- Cell Adhesion Molecules, Neuronal/physiology
- Cell Line
- Cerebral Cortex/abnormalities
- Chlorocebus aethiops
- Extracellular Matrix Proteins/physiology
- Hippocampus/abnormalities
- Humans
- LDL-Receptor Related Proteins
- Lissencephaly/genetics
- Lissencephaly/metabolism
- Lissencephaly/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Neurologic Mutants
- Microtubule-Associated Proteins/deficiency
- Microtubule-Associated Proteins/genetics
- Microtubule-Associated Proteins/metabolism
- Molecular Sequence Data
- Nerve Tissue Proteins/physiology
- Protein Binding
- Protein Interaction Mapping
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, LDL/deficiency
- Receptors, LDL/genetics
- Receptors, LDL/metabolism
- Receptors, LDL/physiology
- Receptors, Lipoprotein/deficiency
- Receptors, Lipoprotein/genetics
- Receptors, Lipoprotein/metabolism
- Receptors, Lipoprotein/physiology
- Recombinant Fusion Proteins/metabolism
- Reelin Protein
- Serine Endopeptidases/physiology
- Signal Transduction/physiology
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Affiliation(s)
- Guangcheng Zhang
- The Cain Foundation Laboratories, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Amir H. Assadi
- The Cain Foundation Laboratories, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Robert S. McNeil
- The Cain Foundation Laboratories, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Uwe Beffert
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Anthony Wynshaw-Boris
- Department of Pediatrics and Medicine, University of California, San Diego School of Medicine, La Jolla, California, United States of America
| | - Joachim Herz
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Gary D. Clark
- The Cain Foundation Laboratories, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neurology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Gabriella D'Arcangelo
- The Cain Foundation Laboratories, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- * To whom correspondence should be addressed. E-mail:
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163
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Katyal S, Gao Z, Monckton E, Glubrecht D, Godbout R. Hierarchical disabled-1 tyrosine phosphorylation in Src family kinase activation and neurite formation. J Mol Biol 2007; 368:349-64. [PMID: 17350651 PMCID: PMC4071145 DOI: 10.1016/j.jmb.2007.01.068] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 01/23/2007] [Accepted: 01/25/2007] [Indexed: 01/11/2023]
Abstract
There are two developmentally regulated alternatively spliced forms of Disabled-1 (Dab1) in the chick retina: an early form (Dab1-E) expressed in retinal precursor cells and a late form (Dab1-L) expressed in neuronal cells. The main difference between these two isoforms is the absence of two Src family kinase (SFK) recognition sites in Dab1-E. Both forms retain two Abl/Crk/Nck recognition sites implicated in the recruitment of SH2 domain-containing signaling proteins. One of the Dab1-L-specific SFK recognition sites, at tyrosine(Y)-198, has been shown to be phosphorylated in Reelin-stimulated neurons. Here, we use Reelin-expressing primary retinal cultures to investigate the role of the four Dab1 tyrosine phosphorylation sites on overall tyrosine phosphorylation, Dab1 phosphorylation, SFK activation and neurite formation. We show that Y198 is essential but not sufficient for maximal Dab1 phosphorylation, SFK activation and neurite formation, with Y232 and Y220 playing particularly important roles in SFK activation and neuritogenesis, and Y185 having modifying effects secondary to Y232 and Y220. Our data support a role for all four Dab1 tyrosine phosphorylation sites in mediating the spectrum of activities associated with Reelin-Dab1 signaling in neurons.
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164
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Qiu S, Zhao LF, Korwek KM, Weeber EJ. Differential reelin-induced enhancement of NMDA and AMPA receptor activity in the adult hippocampus. J Neurosci 2007; 26:12943-55. [PMID: 17167084 PMCID: PMC6674964 DOI: 10.1523/jneurosci.2561-06.2006] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The developmental lamination of the hippocampus and other cortical structures requires a signaling cascade initiated by reelin and its receptors, apoER2 (apolipoprotein E receptor 2) and VLDLR (very-low-density lipoprotein receptor). However, the functional significance of continued reelin expression in the postnatal brain remains poorly understood. Here, we show that reelin application to adult mice hippocampal slices leads to enhanced glutamatergic transmission mediated by NMDA receptors (NMDARs) and AMPA receptors (AMPARs) through distinct mechanisms. Application of recombinant reelin enhanced NMDAR-mediated currents through postsynaptic mechanisms, as revealed by the variance-mean analysis of synaptic NMDAR currents, assessment of spontaneous miniature events, and the levels of NMDAR subunits at synaptic surface. In comparison, nonstationary fluctuation analysis of miniature AMPAR currents and quantification of synaptic surface proteins revealed that reelin-induced enhancement of AMPAR responses was mediated by increased AMPAR numbers. Reelin enhancement of synaptic NMDAR currents was abolished when receptor-associated protein (RAP) or the Src inhibitor 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]-pyrimidine (PP1) was bath applied and was abrogated by including PP1 in the recording electrodes. In comparison, including RAP or an inactive PP1 analog PP3 in the recording electrode was without effect. Interestingly, the increased AMPAR response after reelin application was not blocked by PP1 but was blocked by the phosphoinositide-3' kinase (PI3K) inhibitors wortmannin and LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride]. Furthermore, reelin-induced, PI3K-dependent AMPAR surface insertion was also observed in cultured hippocampal neurons. Together, these results reveal a differential functional coupling of reelin signaling with NMDAR and AMPAR function and define a novel mechanism for controlling synaptic strength and plasticity in the adult hippocampus.
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MESH Headings
- Animals
- Cell Adhesion Molecules, Neuronal/genetics
- Cell Adhesion Molecules, Neuronal/physiology
- Cell Line
- Cells, Cultured
- Excitatory Postsynaptic Potentials/physiology
- Extracellular Matrix Proteins/genetics
- Extracellular Matrix Proteins/physiology
- Female
- Hippocampus/metabolism
- Hippocampus/physiology
- Humans
- Male
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/physiology
- Receptors, AMPA/agonists
- Receptors, AMPA/metabolism
- Receptors, AMPA/physiology
- Receptors, N-Methyl-D-Aspartate/agonists
- Receptors, N-Methyl-D-Aspartate/metabolism
- Receptors, N-Methyl-D-Aspartate/physiology
- Reelin Protein
- Serine Endopeptidases/genetics
- Serine Endopeptidases/physiology
- Signal Transduction/genetics
- src-Family Kinases/physiology
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Affiliation(s)
- Shenfeng Qiu
- Departments of Molecular Physiology and Biophysics and
| | - Lisa F. Zhao
- Departments of Molecular Physiology and Biophysics and
| | | | - Edwin J. Weeber
- Departments of Molecular Physiology and Biophysics and
- Pharmacology
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee 37232-0615
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165
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Nayeem N, Kerr F, Naumann H, Linehan J, Lovestone S, Brandner S. Hyperphosphorylation of tau and neurofilaments and activation of CDK5 and ERK1/2 in PTEN-deficient cerebella. Mol Cell Neurosci 2007; 34:400-8. [PMID: 17208451 DOI: 10.1016/j.mcn.2006.11.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Accepted: 11/15/2006] [Indexed: 12/19/2022] Open
Abstract
Inherited mutations to the tumor suppressor PTEN sporadically lead to cerebellar gangliocytoma characterized by migration defects. This has been modeled by CNS-specific PTEN ablation in mice, but the underlying mechanism cannot be explained by the known role of PTEN in Akt/PKB inactivation. Here we show that the loss of PTEN in mouse cerebellar neurons causes neurodegeneration by hyperphosphorylation of tau and neurofilaments, and activation of Cdk5 and pERK1/2, suggesting that dysregulation of the PTEN/pAkt pathway can mediate neurodegeneration.
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Affiliation(s)
- Naushaba Nayeem
- Department of Neurodegenerative Disease and MRC Prion Unit, Institute of Neurology, University College, London WC1N 3BG, UK
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166
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Abstract
Apolipoprotein E (APOE) is a cholesterol transport protein and an isoform-specific major risk factor for neurodegenerative diseases. The lipoprotein receptors that bind APOE have recently been recognized as pivotal components of the neuronal signalling machinery. The interaction between APOE receptors and one of their ligands, reelin, allows them to function directly as signal transduction receptors at the plasma membrane to control not only neuronal positioning during brain development, but also synaptic plasticity in the adult brain. Here, we review the molecular mechanisms through which APOE, cholesterol, reelin and APOE receptors control synaptic functions that are essential for cognition, learning, memory, behaviour and neuronal survival.
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Affiliation(s)
- Joachim Herz
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texus 75390, USA.
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167
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Hoe HS, Freeman J, Rebeck GW. Apolipoprotein E decreases tau kinases and phospho-tau levels in primary neurons. Mol Neurodegener 2006; 1:18. [PMID: 17166269 PMCID: PMC1713232 DOI: 10.1186/1750-1326-1-18] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 12/13/2006] [Indexed: 11/25/2022] Open
Abstract
Apolipoprotein E (apoE) receptors act as signaling molecules in neurons, altering phosphorylation of numerous proteins after extracellular ligand binding and affecting neurite outgrowth, synapse formation, and neuronal migration. Since apoE is important in the pathogenesis of Alzheimer's disease (AD), we tested whether apoE treatment of neurons affected molecules important to phosphorylation of tau, such as GSK 3β, P35, and CDK5, and the phosphorylation of tau itself. Treatment of primary neurons with 2 uM apoE (or an apoE-derived peptide) decreased levels of phospho-GSK 3β, P35 and CDK5, and decreased levels of phosphorylated forms of tau. A lower concentration of apoE (100 nM) had no effect on these molecules. The alteration of tau phosphorylation by apoE was blocked by an inhibitor of the low-density lipoprotein receptor family, demonstrating the effects were due to receptor interactions. These results demonstrate that apoE affects several downstream signaling cascades in neurons: decreased tau kinases phosphorylation and inhibition of tau phosphorylation at Thr171 and Ser202/Thr205 epitopes. We conclude that apoE can alter levels of tau kinases and phospho-tau epitopes, potentially affecting tau neuropathological changes seen in AD brains.
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Affiliation(s)
- Hyang-Sook Hoe
- Department of Neuroscience, Georgetown University, 3970 Reservoir Road NW, Washington, DC 20057-1464, USA
| | - Jacob Freeman
- Department of Neuroscience, Georgetown University, 3970 Reservoir Road NW, Washington, DC 20057-1464, USA
| | - G William Rebeck
- Department of Neuroscience, Georgetown University, 3970 Reservoir Road NW, Washington, DC 20057-1464, USA
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168
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Rebeck GW, LaDu MJ, Estus S, Bu G, Weeber EJ. The generation and function of soluble apoE receptors in the CNS. Mol Neurodegener 2006; 1:15. [PMID: 17062143 PMCID: PMC1635701 DOI: 10.1186/1750-1326-1-15] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Accepted: 10/24/2006] [Indexed: 01/11/2023] Open
Abstract
More than a decade has passed since apolipoprotein E4 (APOE-ε4) was identified as a primary risk factor for Alzheimer 's disease (AD), yet researchers are even now struggling to understand how the apolipoprotein system integrates into the puzzle of AD etiology. The specific pathological actions of apoE4, methods of modulating apolipoprotein E4-associated risk, and possible roles of apoE in normal synaptic function are still being debated. These critical questions will never be fully answered without a complete understanding of the life cycle of the apolipoprotein receptors that mediate the uptake, signaling, and degradation of apoE. The present review will focus on apoE receptors as modulators of apoE actions and, in particular, explore the functions of soluble apoE receptors, a field almost entirely overlooked until now.
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Affiliation(s)
- G William Rebeck
- Department of Neuroscience, Georgetown University, Washington DC, USA
| | - Mary Jo LaDu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, USA
| | - Steven Estus
- Department of Physiology, University of Kentucky, Lexington, USA
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, USA
| | - Guojun Bu
- Department of Pediatrics, Washington University, St. Louis, USA
- Department of Cell Biology and Physiology, Washington University, St. Louis, USA
- Hope Center for Neurological Disorders, Washington University, St. Louis, USA
| | - Edwin J Weeber
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, USA
- Department of Pharmacology, Vanderbilt University, Nashville, USA
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, USA
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169
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Marín O, Valdeolmillos M, Moya F. Neurons in motion: same principles for different shapes? Trends Neurosci 2006; 29:655-61. [PMID: 17046074 DOI: 10.1016/j.tins.2006.10.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 08/17/2006] [Accepted: 10/04/2006] [Indexed: 01/29/2023]
Abstract
The special conformation of the developing nervous system, in which progenitor zones are largely confined to the lumen of the neural tube, places neuronal migration as one of the most fundamental processes in brain development. Previous studies have shown that different neuronal types adopt distinct morphological modes of migration in the developing brain, indicating that neuronal migration might be a diverse process. Here, we review recent data on the molecular mechanisms underlying neuronal migration that suggest that similar signaling principles are responsible for the frequently variable morphology of different types of migrating neuron. According to this idea, the same basic molecular mechanisms found in other cell types, such as fibroblasts, might have been adapted to the special morphological needs of migrating neurons in different regions of the developing brain.
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Affiliation(s)
- Oscar Marín
- Instituto de Neurociencias de Alicante, CSIC and Universidad Miguel Hernández, 03550 Sant Joan d'Alacant, Spain.
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170
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Stolt PC, Bock HH. Modulation of lipoprotein receptor functions by intracellular adaptor proteins. Cell Signal 2006; 18:1560-71. [PMID: 16725309 DOI: 10.1016/j.cellsig.2006.03.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Accepted: 03/21/2006] [Indexed: 10/24/2022]
Abstract
Members of the low density lipoprotein (LDL) receptor gene family are critically involved in a wide range of physiological processes including lipid and vitamin homeostasis, cellular migration, neurodevelopment, and synaptic plasticity, to name a few. Lipoprotein receptors exert these diverse biological functions by acting as cellular uptake receptors or by inducing intracellular signaling cascades. It was discovered that a short sequence in the intracellular region of all lipoprotein receptors, Asn-Pro-X-Tyr (NPXY) is important for mediating either endocytosis or signal transduction events, and that this motif serves as a binding site for phosphotyrosine-binding (PTB) domain containing scaffold proteins. These molecular adaptors connect the transmembrane receptors with the endocytosis machinery and regulate cellular trafficking, or function as assembly sites for dynamic multi-protein signaling complexes. Whereas the LDL receptor represents the archetype of an endocytic lipoprotein receptor, the structurally closely related apolipoprotein E receptor 2 (apoER2) and very low density lipoprotein (VLDL) receptor activate a kinase-dependent intracellular signaling cascade after binding to the neuronal signaling molecule Reelin. This review focuses on two related PTB domain containing adaptor proteins that mediate these divergent lipoprotein receptor responses, ARH (autosomal recessive hypercholesterolemia protein) and Dab1 (disabled-1), and discusses the structural and molecular basis of this different behaviour.
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Affiliation(s)
- Peggy C Stolt
- Max Planck Institute for Biophysics, Max-von-Laue Str. 3, D-60438 Frankfurt/Main, Germany
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171
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Ide M, Ohnishi T, Murayama M, Matsumoto I, Yamada K, Iwayama Y, Dedova I, Toyota T, Asada T, Takashima A, Yoshikawa T. Failure to support a genetic contribution of AKT1 polymorphisms and altered AKT signaling in schizophrenia. J Neurochem 2006; 99:277-87. [PMID: 16987250 DOI: 10.1111/j.1471-4159.2006.04033.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The protein kinase v-akt murine thymoma viral oncogene homolog (AKT) gene family comprises three human homologs that phosphorylate and inactivate glycogen synthase kinase 3beta (GSK3beta). Studies have reported the genetic association of AKT1 with schizophrenia. Additionally, decreased AKT1 protein expression and the reduced phosphorylation of GSK3beta were reported in this disease, leading to a new theory of attenuated AKT1-GSK3beta signaling in schizophrenia pathogenesis. We have evaluated this theory by performing both genetic and protein expression analyses. A family based association test of AKT1 did not show association with schizophrenia in Japanese subjects. The expression levels of total AKT, AKT1 and phosphorylated GSK3beta detected in the schizophrenic brains from two different brain banks also failed to support the theory. In addition, no attenuated AKT-GSK3beta signaling was observed in the lymphocytes from Japanese schizophrenics, contrasting with previous findings. Importantly, we found that the level of phosphorylated GSK3beta at Ser9 tended to be inversely correlated with postmortem intervals, and that the phosphorylation levels of AKT were inversely correlated with brain pH, issues not assessed in the previous study. These data introduce a note of caution when estimating the phosphorylation levels of GSK3beta and AKT in postmortem brains. Collectively, this study failed to support reduced signaling of the AKT-GSK3beta molecular cascade in schizophrenia.
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Affiliation(s)
- Masayuki Ide
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, Saitama, Japan
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172
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Zhao S, Chai X, Bock HH, Brunne B, Förster E, Frotscher M. Rescue of the reeler phenotype in the dentate gyrus by wild-type coculture is mediated by lipoprotein receptors for Reelin and Disabled 1. J Comp Neurol 2006; 495:1-9. [PMID: 16432903 DOI: 10.1002/cne.20846] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Reelin is a positional signal for the lamination of the dentate gyrus. In the reeler mutant lacking Reelin, granule cells are scattered all over the dentate gyrus. We have recently shown that the reeler phenotype of the dentate gyrus can be rescued in vitro by coculturing reeler hippocampal slices with slices from wild-type hippocampus. Here we studied whether Reelin from other brain regions can similarly induce this rescue effect and whether it is mediated via the Reelin receptors apolipoprotein E receptor 2 (ApoER2) and very-low-density lipoprotein receptor (VLDLR). We found that coculturing reeler hippocampal slices with slices from wild-type olfactory bulb, cerebellum, and neocortex rescued the reeler phenotype as seen before with hippocampal slices, provided that the Reelin-synthesizing cells of these regions were placed near the marginal zone of the reeler hippocampal slice. However, coculturing wild-type hippocampal slices with hippocampal slices from mutants deficient in ApoER2 and VLDLR did not rescue the reeler-like phenotype in these cultures. Similarly, no rescue of the reeler-like phenotype was observed in slices from mutants lacking Disabled 1 (Dab1), an adapter protein downstream of Reelin receptors. Conversely, reeler hippocampal slices were rescued by coculturing them with slices from Dab1(-/-) mutants or ApoER2(-/-)/VLDLR(-/-) mice. These findings show that Reelin from other brain regions can substitute for the loss of hippocampal Reelin and that rescue of the reeler phenotype observed in our coculture studies is mediated via lipoprotein receptors for Reelin and Dab1.
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Affiliation(s)
- Shanting Zhao
- Institut für Anatomie und Zellbiologie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
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173
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Beffert U, Durudas A, Weeber EJ, Stolt PC, Giehl KM, Sweatt JD, Hammer RE, Herz J. Functional dissection of Reelin signaling by site-directed disruption of Disabled-1 adaptor binding to apolipoprotein E receptor 2: distinct roles in development and synaptic plasticity. J Neurosci 2006; 26:2041-52. [PMID: 16481437 PMCID: PMC6674917 DOI: 10.1523/jneurosci.4566-05.2006] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Reelin signaling pathway controls neuronal positioning in human and mouse brain during development as well as modulation of long-term potentiation (LTP) and behavior in the adult. Reelin signals by binding to two transmembrane receptors, apolipoprotein E receptor 2 (Apoer2) and very-low-density lipoprotein receptor. After Reelin binds to the receptors, Disabled-1 (Dab1), an intracellular adaptor protein that binds to the cytoplasmic tails of the receptors, becomes phosphorylated on tyrosine residues, initiating a signaling cascade that includes activation of Src-family kinases and Akt. Here, we have created a line of mutant mice (Apoer2 EIG) in which the Apoer2 NFDNPVY motif has been altered to EIGNPVY to disrupt the Apoer2-Dab1 interaction to further study Reelin signaling in development and adult brain. Using primary neuronal cultures stimulated with recombinant Reelin, we find that normal Reelin signaling requires the wild-type NFDNPVY sequence and likely the interaction of Apoer2 with Dab1. Furthermore, examination of hippocampal, cortical, and cerebellar layering reveals that the NFDNPVY sequence of Apoer2 is indispensable for normal neuronal positioning during development of the brain. Adult Apoer2 EIG mice display severe abnormalities in LTP and behavior that are distinct from those observed for mice lacking Apoer2. In Apoer2 EIG slices, LTP degraded to baseline within 30 min, and this was prevented in the presence of Reelin. Together, these findings emphasize the complexity of Reelin signaling in the adult brain, which likely requires multiple adaptor protein interactions with the intracellular domain of Apoer2.
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174
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Botella-López A, Burgaya F, Gavín R, García-Ayllón MS, Gómez-Tortosa E, Peña-Casanova J, Ureña JM, Del Río JA, Blesa R, Soriano E, Sáez-Valero J. Reelin expression and glycosylation patterns are altered in Alzheimer's disease. Proc Natl Acad Sci U S A 2006; 103:5573-8. [PMID: 16567613 PMCID: PMC1414634 DOI: 10.1073/pnas.0601279103] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Indexed: 01/24/2023] Open
Abstract
Reelin is a glycoprotein that is essential for the correct cytoarchitectonic organization of the developing CNS. Its function in the adult brain is less understood, although it has been proposed that Reelin is involved in signaling pathways linked to neurodegeneration. Here we analyzed Reelin expression in brains and cerebrospinal fluid (CSF) from Alzheimer's disease (AD) patients and nondemented controls. We found a 40% increase in the Reelin protein levels in the cortex of AD patients compared with controls. Similar increases were detected at the Reelin mRNA transcriptional level. This expression correlates with parallel increases in CSF but not in plasma samples. Next, we examined whether CSF Reelin levels were also altered in neurological diseases, including frontotemporal dementia, progressive supranuclear palsy, and Parkinson's disease. The Reelin 180-kDa band increased in all of the neurodegenerative disorders analyzed. Moreover, the 180-kDa Reelin levels correlated positively with Tau protein in CSF. Finally, we studied the pattern of Reelin glycosylation by using several lectins and the anti-HNK-1 antibody. Glycosylation differed in plasma and CSF. Furthermore, the pattern of Reelin lectin binding differed between the CSF of controls and in AD. Our results show that Reelin is up-regulated in the brain and CSF in several neurodegenerative diseases and that CSF and plasma Reelin have distinct cellular origins, thereby supporting that Reelin is involved in the pathogenesis of a number of neurodegenerative diseases.
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Affiliation(s)
- Arancha Botella-López
- *Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, E-03550 Sant Joan d’Alacant, Spain
| | - Ferran Burgaya
- Institut de Recerca Biomèdica/Parc Cientific de Barcelona and Department of Cell Biology, University of Barcelona, E-08028 Barcelona, Spain
| | - Rosalina Gavín
- Institut de Recerca Biomèdica/Parc Cientific de Barcelona and Department of Cell Biology, University of Barcelona, E-08028 Barcelona, Spain
| | - M. Salud García-Ayllón
- *Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, E-03550 Sant Joan d’Alacant, Spain
| | - Estrella Gómez-Tortosa
- Neurology Department, Fundación Jiménez Díaz, Brain Bank for Neurological Research, Complutense University, E-28040 Madrid, Spain
| | - Jordi Peña-Casanova
- Neurology Department, Hospital del Mar, Institut Municipal d’Assistencia Sanitaria, E-08003 Barcelona, Spain; and
| | - Jesús M. Ureña
- Institut de Recerca Biomèdica/Parc Cientific de Barcelona and Department of Cell Biology, University of Barcelona, E-08028 Barcelona, Spain
| | - José A. Del Río
- Institut de Recerca Biomèdica/Parc Cientific de Barcelona and Department of Cell Biology, University of Barcelona, E-08028 Barcelona, Spain
| | - Rafael Blesa
- Neurology Department, Hospital de la Santa Creu i Sant Pau, E-08025 Barcelona, Spain
| | - Eduardo Soriano
- Institut de Recerca Biomèdica/Parc Cientific de Barcelona and Department of Cell Biology, University of Barcelona, E-08028 Barcelona, Spain
| | - Javier Sáez-Valero
- *Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, E-03550 Sant Joan d’Alacant, Spain
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175
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Fatemi SH. Reelin glycoprotein in autism and schizophrenia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2006; 71:179-87. [PMID: 16512351 DOI: 10.1016/s0074-7742(05)71008-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- S Hossein Fatemi
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis 55455, USA
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176
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Mayer H, Duit S, Hauser C, Schneider WJ, Nimpf J. Reconstitution of the Reelin signaling pathway in fibroblasts demonstrates that Dab1 phosphorylation is independent of receptor localization in lipid rafts. Mol Cell Biol 2006; 26:19-27. [PMID: 16354676 PMCID: PMC1317641 DOI: 10.1128/mcb.26.1.19-27.2006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Reelin signaling pathway operates in migrating neurons and is indispensable for their correct positioning during embryonic brain development. Many biochemical and cell biological studies to dissect the Reelin pathway at the molecular level are hampered by the lack of a cell line harboring a functional Reelin signaling pathway. Here we present fibroblast cell lines in which all required functional components of the pathway have been reconstituted. These cells react upon Reelin treatment in the same way as primary neurons. We have subsequently used these cell lines to study the subcellular localization of ApoER2 and the VLDL receptor and could demonstrate that receptor-mediated Dab1 phosphorylation does not depend on lipid rafts and that phosphorylated Dab1 remains bound to the receptor tail when the pathway is activated by Reelin.
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Affiliation(s)
- Harald Mayer
- Max F. Perutz Laboratories, Department of Medical Biochemistry, University Department at the Vienna Biocenter, Medical University of Vienna, Vienna, Austria
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177
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Ohshima T, Suzuki H, Morimura T, Ogawa M, Mikoshiba K. Modulation of Reelin signaling by Cyclin-dependent kinase 5. Brain Res 2006; 1140:84-95. [PMID: 16529723 DOI: 10.1016/j.brainres.2006.01.121] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/22/2006] [Accepted: 01/30/2006] [Indexed: 10/24/2022]
Abstract
The Reelin signaling and Cyclin-dependent kinase 5 (Cdk5) both regulate neuronal positioning in the developing brain. Using double-transgenic mice, we have previously shown that these two signaling pathways lie in parallel fashion and have a genetic interaction. Disabled-1 (Dab1), an adapter protein, mediates Reelin signaling and becomes tyrosine-phosphorylated on the binding of Reelin to its receptors. Several isoforms of Dab1 are expressed in embryonic mouse brain, and p80 [Dab1(555)] is the major protein translated. In the present study, we investigated whether Cdk5-mediated phosphorylation of Dab1 modulates Reelin signaling. Cdk5 phosphorylates p80 Dab1 at multiple sites in its carboxyl-terminal region, and tyrosine phosphorylation of p80 Dab1 by Fyn tyrosine kinase is attenuated by this Cdk5-mediated phosphorylation in vitro. Tyrosine phosphorylation of p80 Dab1 induced by exogenous Reelin is enhanced in Cdk5-deficient neurons, corroborating the inhibitory effect of Cdk5-mediated Ser/Thr phosphorylation on tyrosine phosphorylation of p80 Dab1. Another isoform, p45 Dab1 [Dab1(271)], however, is phosphorylated by Cdk5 at one serine residue within a unique carboxyl-terminal region, and its serine phosphorylation enhances tyrosine phosphorylation by Fyn and results in progressive degradation of p45 Dab1. These results indicate that Cdk5 modulates Reelin signaling through the Ser/Thr phosphorylation of Dab1 differently in an isoform-specific manner.
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Affiliation(s)
- Toshio Ohshima
- Laboratory for Developmental Neurobiology, Brain Science Institute, RIKEN, Wako, Saitama, Japan.
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178
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Chen Y, Beffert U, Ertunc M, Tang TS, Kavalali ET, Bezprozvanny I, Herz J. Reelin modulates NMDA receptor activity in cortical neurons. J Neurosci 2006; 25:8209-16. [PMID: 16148228 PMCID: PMC6725528 DOI: 10.1523/jneurosci.1951-05.2005] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Reelin, a large protein that regulates neuronal migration during embryonic development, activates a conserved signaling pathway that requires its receptors, very low-density lipoprotein receptor and apolipoprotein E receptor 2, the cytoplasmic adaptor protein Disabled-1 (Dab1), and Src family kinases (SFK). Reelin also markedly enhances long-term potentiation in the adult hippocampus, suggesting that this developmental signaling pathway can physiologically modulate learning and behavior. Here, we show that Reelin can regulate NMDA-type glutamate receptor activity through a mechanism that requires SFKs and Dab1. Reelin mediates tyrosine phosphorylation of and potentiates calcium influx through NMDA receptors in primary wild-type cortical neurons but not in Dab1 knock-out neurons or in cells in which Reelin binding to its receptors is blocked by a receptor antagonist. Inhibition of SFK abolishes Reelin-induced and glutamate-dependent enhancement of calcium influx. We also show that Reelin-induced augmentation of Ca2+ entry through NMDA receptors increases phosphorylation and nuclear translocation of the transcription factor cAMP-response element binding protein. Thus, Reelin may physiologically modulate learning and memory by modulating NMDA receptor functions.
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Affiliation(s)
- Ying Chen
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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179
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Simó S, Pujadas L, Segura MF, La Torre A, Del Río JA, Ureña JM, Comella JX, Soriano E. Reelin induces the detachment of postnatal subventricular zone cells and the expression of the Egr-1 through Erk1/2 activation. ACTA ACUST UNITED AC 2006; 17:294-303. [PMID: 16514107 DOI: 10.1093/cercor/bhj147] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Reelin binds to very low-density lipoprotein receptor and apolipoprotein E receptor 2, thereby inducing mDab1 phosphorylation and activation of the phosphatidylinositide 3 kinase (PI3K) pathway. Here we demonstrate that Reelin activates the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) pathway, which leads to the phosphorylation of Erk1/2 proteins. The inhibition of Src family kinases (SFK) blocked Reelin-dependent Erk1/2 activation. This was also shown in neuronal cultures from mDab1-deficient mice. Although rat sarcoma viral oncogene was weakly activated upon Reelin treatment, pharmacological inhibition of the PI3K pathway blocked Reelin-dependent ERK activation, which indicates cross talk between the ERK and PI3K pathways. We show that blockade of the ERK pathway does not prevent the chain migration of neurons from the subventricular zone (SVZ) but does inhibit the Reelin-dependent detachment of migrating neurons. We also show that Reelin induces the transcription of the early growth response 1 transcription factor. Our findings demonstrate that Reelin triggers ERK signaling in an SFK/mDab1- and PI3K-dependent manner and that ERK activation is required for Reelin-dependent transcriptional activation and the detachment of neurons migrating from the SVZ.
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Affiliation(s)
- Sergi Simó
- Developmental Neurobiology and Regeneration Laboratory, Barcelona Science Park-IRB and Department of Cell Biology, University of Barcelona, E-08028 Barcelona, Spain
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180
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Chadborn NH, Ahmed AI, Holt MR, Prinjha R, Dunn GA, Jones GE, Eickholt BJ. PTEN couples Sema3A signalling to growth cone collapse. J Cell Sci 2006; 119:951-7. [PMID: 16495486 DOI: 10.1242/jcs.02801] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Distinct changes in glycogen synthase kinase-3 (GSK-3) signalling can regulate neuronal morphogenesis including the determination and maintenance of axonal identity, and are required for neurotrophin-mediated axon elongation. In addition, we have previously shown a dependency on GSK-3 activation in the semaphorin 3A (Sema3A)-mediated growth-cone-collapse response of sensory neurons. Regulation of GSK-3 activity involves the intermediate signalling lipid phosphatidylinositol 3,4,5-trisphosphate, which can be modulated by phosphatidylinositol 3-kinase (PI3K) and the tumour suppressor PTEN. We report here the involvement of PTEN in the Sema3A-mediated growth cone collapse. Sema3A suppresses PI3K signalling concomitant with the activation of GSK-3, which depends on the phosphatase activity of PTEN. PTEN is highly enriched in the axonal compartment and the central domain of sensory growth cones during axonal extension, where it colocalises with microtubules. Following exposure to Sema3A, PTEN accumulates rapidly at the growth cone membrane suggesting a mechanism by which PTEN couples Sema3A signalling to growth cone collapse. These findings demonstrate a dependency on PTEN to regulate GSK-3 signalling in response to Sema3A and highlight the importance of subcellular distributions of PTEN to control growth cone behaviour.
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Affiliation(s)
- Neil H Chadborn
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Campus, London, SE1 1UL, UK
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181
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Porcionatto MA. The extracellular matrix provides directional cues for neuronal migration during cerebellar development. Braz J Med Biol Res 2006; 39:313-20. [PMID: 16501810 DOI: 10.1590/s0100-879x2006000300001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Normal central nervous system development relies on accurate intrinsic cellular programs as well as on extrinsic informative cues provided by extracellular molecules. Migration of neuronal progenitors from defined proliferative zones to their final location is a key event during embryonic and postnatal development. Extracellular matrix components play important roles in these processes, and interactions between neurons and extracellular matrix are fundamental for the normal development of the central nervous system. Guidance cues are provided by extracellular factors that orient neuronal migration. During cerebellar development, the extracellular matrix molecules laminin and fibronectin give support to neuronal precursor migration, while other molecules such as reelin, tenascin, and netrin orient their migration. Reelin and tenascin are extracellular matrix components that attract or repel neuronal precursors and axons during development through interaction with membrane receptors, and netrin associates with laminin and heparan sulfate proteoglycans, and binds to the extracellular matrix receptor integrins present on the neuronal surface. Altogether, the dynamic changes in the composition and distribution of extracellular matrix components provide external cues that direct neurons leaving their birthplaces to reach their correct final location. Understanding the molecular mechanisms that orient neurons to reach precisely their final location during development is fundamental to understand how neuronal misplacement leads to neurological diseases and eventually to find ways to treat them.
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Affiliation(s)
- M A Porcionatto
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
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182
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Parisiadou L, Efthimiopoulos S. Expression of mDab1 promotes the stability and processing of amyloid precursor protein and this effect is counteracted by X11alpha. Neurobiol Aging 2006; 28:377-88. [PMID: 16458391 DOI: 10.1016/j.neurobiolaging.2005.12.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 12/21/2005] [Accepted: 12/22/2005] [Indexed: 10/25/2022]
Abstract
The cytoplasmic tail of amyloid precursor protein (APP) possesses the NPTY motif to which several phosphotyrosine-binding domain-containing proteins bind, including X11alpha and mDab1. X11alpha has been shown to slow cellular APP processing and reduce secretion of Abeta peptides. However, the effect of mDab1 on APP processing has not been determined. Here, we show that mDab1 increases the levels of cellular mature APP and promotes its processing by the secretases in both transiently transfected HEK 293 cells and in neuroglioma U251 cells. These effects derive specifically from the interaction of APP with mDab1 since they are not observed in APP deletion mutants lacking the interaction module NPTY. We further demonstrate that mDab1 enhances cell surface expression of APP, possibly by interfering with its endocytosis. Interestingly, X11alpha and mDab1 exert opposing effects on APP processing. However, when both proteins are co-expressed the effect of X11alpha overrides that of mDab1. Taken together, these results suggest that the relative stoichiometry and binding affinity of the adaptor proteins determines the final outcome on APP metabolism.
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Affiliation(s)
- Loukia Parisiadou
- Division of Animal and Human Physiology, Department of Biology, National & Kapodistrian University of Athens, 157 84 Panepistimiopolis, Ilisia, Athens, Greece
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183
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Förster E, Jossin Y, Zhao S, Chai X, Frotscher M, Goffinet AM. Recent progress in understanding the role of Reelin in radial neuronal migration, with specific emphasis on the dentate gyrus. Eur J Neurosci 2006; 23:901-9. [PMID: 16519655 DOI: 10.1111/j.1460-9568.2006.04612.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Ten years following identification of Reelin as the product of the gene mutated in reeler mice, the signalling pathway activated by Reelin is being progressively unravelled with the identification of lipoprotein receptors as reelin receptors, of the Dab1 adapter and of some other proximal components in target cells. However, we are still a long way from understanding the action of this complex protein during brain development and maturation. The present review is organized in two parts. First, we summarize our present understanding of Reelin signalling. Then, we review critically some cell biological mechanisms for the action of Reelin based on recent studies on the development of the dentate gyrus, which has proved an extremely useful and tractable model system.
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Affiliation(s)
- Eckart Förster
- Institut für Anatomie und Zellbiologie, Albert-Ludwigs-Universität Freiburg, Albertstr. 17, D-79104 Freiburg, Germany
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184
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Sato N, Fukushima N, Chang R, Matsubayashi H, Goggins M. Differential and epigenetic gene expression profiling identifies frequent disruption of the RELN pathway in pancreatic cancers. Gastroenterology 2006; 130:548-65. [PMID: 16472607 DOI: 10.1053/j.gastro.2005.11.008] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Accepted: 11/02/2005] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Recently described genome-wide approaches robustly detect many candidate genes that are regulated by DNA methylation, but many of these genes do not represent important targets for functional inactivation. Here we used a microarray-based strategy to identify biologically relevant genes associated with epigenetic silencing in pancreatic cancer. METHODS We compared information from differential gene expression analysis with the transcriptional responses to epigenetic modifiers. RESULTS Using this approach, we identified 7 novel targets for aberrant methylation in pancreatic cancer. One of the genes identified, RELN (Reelin), a key regulator of neuronal migration, is frequently silenced in pancreatic cancers, as are several of its downstream mediators. Importantly, small interfering RNA-mediated knockdown of RELN in pancreatic cancer cells that retain RELN expression resulted in greatly enhanced cell motility, invasiveness, and colony-forming ability. Increased cell motility was also induced by knockdown of downstream components of the RELN pathway, including ApoER2, VLDLR, and DAB1. Treatment of pancreatic cancer cells with histone deacetylase inhibitors, valproic acid and suberoylanilide hydroxamic acid, restored the expression of RELN and DAB1 and markedly inhibited their migration. CONCLUSIONS The high prevalence of the silencing of RELN pathway components and its reversal by histone deacetylase inhibitors suggest the importance of this pathway as a diagnostic and therapeutic target for pancreatic cancer.
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Affiliation(s)
- Norihiro Sato
- Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
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185
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Serajee FJ, Zhong H, Mahbubul Huq AHM. Association of Reelin gene polymorphisms with autism. Genomics 2005; 87:75-83. [PMID: 16311013 DOI: 10.1016/j.ygeno.2005.09.008] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2004] [Revised: 09/06/2005] [Accepted: 09/19/2005] [Indexed: 10/25/2022]
Abstract
Genome scans indicate a linkage of autism to the chromosome 7q21-q36 region. Recent studies suggest that the Reelin gene may be one of the loci contributing to the positive linkage between chromosome 7q and autism. However, these studies were relatively small scale, using a few markers in the gene. We investigated 34 single nucleotide polymorphisms (SNPs) in the Reelin gene with an average spacing between the SNPs of 15 kb for evidence of association with autism. There were significant differences in the transmission of the alleles of exon 22 and intron 59 SNP to autistic subjects. Our findings support a role for the Reelin gene in the susceptibility to autism.
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Affiliation(s)
- Fatema J Serajee
- Department of Pediatrics, Wayne State University, Detroit, MI 48201, USA
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186
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Beffert U, Weeber EJ, Durudas A, Qiu S, Masiulis I, Sweatt JD, Li WP, Adelmann G, Frotscher M, Hammer RE, Herz J. Modulation of synaptic plasticity and memory by Reelin involves differential splicing of the lipoprotein receptor Apoer2. Neuron 2005; 47:567-79. [PMID: 16102539 DOI: 10.1016/j.neuron.2005.07.007] [Citation(s) in RCA: 354] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Revised: 05/19/2005] [Accepted: 07/07/2005] [Indexed: 11/28/2022]
Abstract
Apolipoprotein E receptor 2 (Apoer2), a member of the LDL receptor gene family, and its ligand Reelin control neuronal migration during brain development. Apoer2 is also essential for induction of long-term potentiation (LTP) in the adult brain. Here we show that Apoer2 is present in the postsynaptic densities of excitatory synapses where it forms a functional complex with NMDA receptors. Reelin signaling through Apoer2 markedly enhances LTP through a mechanism that requires the presence of amino acids encoded by an exon in the intracellular domain of Apoer2. This exon is alternatively spliced in an activity-dependent manner and is required for Reelin-induced tyrosine phosphorylation of NMDA receptor subunits. Mice constitutively lacking the exon perform poorly in learning and memory tasks. Thus, alternative splicing of Apoer2, a novel component of the NMDA receptor complex, controls the modulation of NMDA receptor activity, synaptic neurotransmission, and memory by Reelin.
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Affiliation(s)
- Uwe Beffert
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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187
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Cuitino L, Matute R, Retamal C, Bu G, Inestrosa NC, Marzolo MP. ApoER2 is endocytosed by a clathrin-mediated process involving the adaptor protein Dab2 independent of its Rafts' association. Traffic 2005; 6:820-38. [PMID: 16101684 DOI: 10.1111/j.1600-0854.2005.00320.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The apolipoprotein E receptor 2 (apoER2) is a member of the low-density lipoprotein receptor family which binds ligands such as reelin, apolipoprotein E and apolipoprotein J/clusterin and has been shown to play roles in neuronal migration during development and in male fertility. The function of apoER2 mainly depends on cellular signaling triggered by ligand binding. Although the receptor is internalized, the mechanism and functional significance of its endocytic trafficking remain unclear. Apolipoprotein E receptor 2 partitions into lipid rafts and interacts with caveolin-1, a feature that could modulate its endocytic behavior. Recent evidence also suggested that apoER2 might be endocytosed by a pathway independent of clathrin. Here, we show that despite a raft association, apoER2 internalization depends on its cytoplasmic FxNPXY motif that is similar to canonical motifs for clathrin-mediated endocytosis. This motif mediates receptor binding to the adaptor protein Dab2, which can interact directly with clathrin. Several inhibitory conditions of clathrin-mediated endocytosis, including expression of the dominant negative forms of eps15 and Dab2, decreased apoER2 internalization. In contrast, treatment with the drug nystatin, which blocks the caveolar/raft internalization pathway, has no effect on the receptor's endocytosis. Neither the transmembrane nor the proline-rich insert of the cytoplasmic domain, which has been previously reported to exclude the receptor from the clathrin-mediated pathway, altered apoER2 endocytic activity. These studies indicate that apoER2 internalizes through a clathrin-mediated pathway and that its association with caveolar and noncaveolar rafts does not determine its endocytosis.
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Affiliation(s)
- Loreto Cuitino
- FONDAP Center for Cell Regulation and Pathology, Joaquín V. Luco, Department of Cell and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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188
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Qiu S, Korwek KM, Weeber EJ. A fresh look at an ancient receptor family: emerging roles for low density lipoprotein receptors in synaptic plasticity and memory formation. Neurobiol Learn Mem 2005; 85:16-29. [PMID: 16198608 DOI: 10.1016/j.nlm.2005.08.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 07/30/2005] [Accepted: 08/11/2005] [Indexed: 01/11/2023]
Abstract
The well-known family of low-density lipoprotein receptors represents a collection of ancient membrane receptors that have been remarkably conserved throughout evolution. These multifunctional receptors, known to regulate cholesterol transport, are becoming increasingly interesting to the neuroscience community due to their ability to transduce a diversity of extracellular signals across the membrane in the adult CNS. Their roles in modulating synaptic plasticity and necessity in hippocampus-specific learning and memory have recently come to light. In addition, genetic, biochemical and behavioral studies have implicated these signaling systems in a number of human neurodegenerative and neuropsychiatric disorders involving loss of cognitive ability, such as Alzheimer's disease, schizophrenia and autism. This review describes the known functions of these receptors and discusses their potential role in processes of synaptic regulation and memory formation.
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Affiliation(s)
- Shenfeng Qiu
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232-0615, USA
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189
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Niu S, Renfro A, Quattrocchi CC, Sheldon M, D'Arcangelo G. Reelin promotes hippocampal dendrite development through the VLDLR/ApoER2-Dab1 pathway. Neuron 2005; 41:71-84. [PMID: 14715136 DOI: 10.1016/s0896-6273(03)00819-5] [Citation(s) in RCA: 290] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Reelin is a secreted glycoprotein that regulates neuronal positioning in cortical brain structures through the VLDLR and ApoER2 receptors and the adaptor protein Dab1. In addition to cellular disorganization, dendrite abnormalities are present in the brain of reeler mice lacking Reelin. It is unclear whether these defects are due primarily to cellular ectopia or the absence of Reelin. Here we examined dendrite development in the hippocampus of normal and mutant mice and in dissociated cultures. We found that dendrite complexity is severely reduced in homozygous mice deficient in Reelin signaling both in vivo and in vitro, and it is also reduced in heterozygous mice in the absence of cellular ectopia. Addition of Reelin interfering antibodies, receptor antagonists, and Dab1 phosphorylation inhibitors prevented dendrite outgrowth from normal neurons, whereas addition of recombinant Reelin rescued the deficit in reeler cultures. Thus, the same signaling pathway controls both neuronal migration and dendrite maturation.
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Affiliation(s)
- Sanyong Niu
- The Cain Foundation Laboratories, Houston, TX 77030, USA
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190
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Huang Y, Shah V, Liu T, Keshvara L. Signaling through Disabled 1 requires phosphoinositide binding. Biochem Biophys Res Commun 2005; 331:1460-8. [PMID: 15883038 DOI: 10.1016/j.bbrc.2005.04.064] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Indexed: 11/18/2022]
Abstract
The Reelin signaling pathway plays a critical role in the correct positioning of neurons within the developing brain. Within this pathway, Disabled 1 (Dab1) serves as an intracellular adaptor that is tyrosine phosphorylated when Reelin, a secreted glycoprotein, binds to the lipoprotein receptors VLDLR and ApoER2 on the surface of neurons. The phosphotyrosine-binding (PTB) domain within its amino terminus enables Dab1 to recognize and bind to a conserved sequence motif within the cytoplasmic tails of the receptors. In addition, the PTB contains a Pleckstrin Homology-like subdomain that binds to phosphoinositides. Here, we show that the phosphoinositide-binding region within Dab1 PTB domain is required for membrane localization and basal tyrosine phosphorylation of Dab1 independently of VLDLR and ApoER2. Furthermore, receptor-independent membrane targeting of Dab1 is required for its interaction with Src and Crk, and disruption of phosphoinositide binding also blocks subsequent Reelin-induced tyrosine phosphorylation of Dab1.
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Affiliation(s)
- Yongcheng Huang
- Division of Pharmacology, College of Pharmacy, The Ohio State University, 500 W 12th Avenue, Columbus, OH 43210, USA
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191
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Kang DE, Yoon IS, Repetto E, Busse T, Yermian N, Ie L, Koo EH. Presenilins mediate phosphatidylinositol 3-kinase/AKT and ERK activation via select signaling receptors. Selectivity of PS2 in platelet-derived growth factor signaling. J Biol Chem 2005; 280:31537-47. [PMID: 16014629 DOI: 10.1074/jbc.m500833200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The Alzheimer's disease-linked genes, PS1 and PS2, are required for intramembrane proteolysis of multiple type I proteins, including Notch and amyloid precursor protein. In addition, it has been documented that PS1 positively regulates, whereas PS1 familial Alzheimer disease mutations suppress, phosphatidylinositol 3-kinase (PI3K)/Akt activation, a pathway known to inactivate glycogen synthase kinase-3 and reduce tau phosphorylation. In this study, we show that the loss of presenilins not only inhibits PI3K/Akt signaling and increases tau phosphorylation but also suppresses the MEK/ERK pathway. The deficits in Akt and ERK activation in cells deficient in both PS1 and PS2 (PS-/-) are evident after serum withdrawal and stimulation with fetal bovine serum or ligands of select receptor tyrosine kinases, platelet-derived growth factor receptor beta (PDGFR beta) and PDGFR alpha, but not insulin-like growth factor-1R and epidermal growth factor receptor. The defects in PDGF signaling in PS-/- cells are due to reduced expression of PDGF receptors. Whereas fetal bovine serum-induced Akt activation is reconstituted by both PS1 and PS2 in PS-/- cells, PDGF signaling is selectively restored by PS2 but not PS1 and is dependent on the N-terminal fragment of PS2 but not gamma-secretase activity or the hydrophilic loop of PS2. The rescue of PDGF receptor expression and activation by PS2 is facilitated by FHL2, a PS2-interacting transcriptional co-activator. Finally, we present evidence that PS1 mutations interfere with this PS2-mediated activity by reducing PS2 fragments. These findings highlight important roles of both presenilins in Akt and ERK signaling via select signaling receptors.
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Affiliation(s)
- David E Kang
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093, USA.
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192
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Abstract
Polyglutamine (polyQ)-expansion diseases are dominantly inherited adult-onset neurodegenerative diseases with unknown pathogenic mechanisms. Current models for pathogenesis include potential toxic effects of polyQ proteins, interference with survival pathways and deregulated gene transcription. Recently, nuclear and aggregate-independent alterations in fast axonal transport (FAT) have been demonstrated for several different polyQ disease models. Given the unique vulnerability of neurons to decrements in FAT, we propose an alternative model for polyQ disease pathogenesis. In this model, FAT is compromised because polyQ proteins affect enzymatic activities involved in FAT regulation. Decrements in FAT ultimately result in a failure to deliver essential cargos to specific neuronal subdomains, including presynaptic terminals, eventually leading to neuronal dysfunction and death. Pharmacological manipulation of such activities might provide the basis for new therapeutic strategies for treating polyQ diseases.
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Affiliation(s)
- Gerardo Morfini
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60607, USA
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193
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Abstract
Apolipoprotein E is a genetic risk factor for Alzheimer's disease, and the apoE protein is associated with beta-amyloid deposits in Alzheimer's disease brain. We examined signaling pathways stimulated by apoE in primary neurons in culture. ApoE and an apoE-derived peptide activated several intracellular kinases, including prominently extracellular signal-regulated kinase 1/2 (ERK1/2). ERK1/2 activation by apoE was blocked by an inhibitor of the low-density lipoprotein receptor family, the specific NMDA glutamate receptor antagonist MK 801 and other calcium channel blockers. Activation of apoE receptors also induced tyrosine phosphorylation of Dab1, an adaptor protein of apoE receptors, but experiments in Dab1 knockout neurons demonstrated that Dab1 was not necessary for ERK activation. In contrast, apoE treatment of primary neurons decreased activation of c-Jun N-terminal kinase, a kinase that interacts with another apoE receptor adaptor protein, c-Jun N-terminal kinase-interacting protein. This change also depended on interactions with the low-density lipoprotein receptor family but was independent of calcium channels. c-Jun N-terminal kinase deactivation by apoE was blocked by gamma-secretase inhibitors and pertussis toxin. These results demonstrate that apoE affects several signaling cascades in neurons: increased disabled phosphorylation, activation of the ERK1/2 pathway (dependent on calcium influx via the NMDA receptor) and inhibition of the c-Jun N-terminal kinase 1/2 pathway (dependent on gamma-secretase and G proteins).
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Affiliation(s)
- Hyang-Sook Hoe
- Department of Neuroscience, Georgetown University, Washington, DC 20057-1464, USA
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194
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Fatemi SH, Snow AV, Stary JM, Araghi-Niknam M, Reutiman TJ, Lee S, Brooks AI, Pearce DA. Reelin signaling is impaired in autism. Biol Psychiatry 2005; 57:777-87. [PMID: 15820235 DOI: 10.1016/j.biopsych.2004.12.018] [Citation(s) in RCA: 201] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2004] [Revised: 04/23/2004] [Accepted: 12/09/2004] [Indexed: 12/22/2022]
Abstract
BACKGROUND Autism is a severe neurodevelopmental disorder with genetic and environmental etiologies. Recent genetic linkage studies implicate Reelin glycoprotein in causation of autism. To further investigate these studies, brain levels of Reelin protein and mRNA and mRNAs for VLDLR, Dab-1, and GSK3 were investigated. METHODS Postmortem superior frontal, parietal, and cerebellar cortices of age, gender, and postmortem interval-matched autistic and control subjects were subjected to SDS-PAGE and Western blotting of Reelin protein. Quantitative reverse transcriptase polymerase chain reaction analysis of Reelin, VLDL-R, Dab-1, and GSK3 mRNA species in superior frontal and cerebellar cortices of autistic and control subjects were also performed. RESULTS Reelin 410, 330, and 180 kDa/beta-actin values were reduced significantly in frontal and cerebellar, and nonsignificantly in parietal, areas of autistic brains versus control subjects, respectively. The mRNAs for Reln and Dab-1 were reduced significantly whereas the mRNA for Reln receptor VLDLR was elevated significantly in superior frontal and cerebellar areas of autistic brains versus control brains, respectively. CONCLUSIONS Reductions in Reelin protein and mRNA and Dab 1 mRNA and elevations in Reln receptor VLDLR mRNA demonstrate impairments in the Reelin signaling system in autism, accounting for some of the brain structural and cognitive deficits observed in the disorder.
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Affiliation(s)
- S Hossein Fatemi
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota, Minneapolis, MN 55455, USA.
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195
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Jossin Y. Neuronal migration and the role of reelin during early development of the cerebral cortex. Mol Neurobiol 2005; 30:225-51. [PMID: 15655250 DOI: 10.1385/mn:30:3:225] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Accepted: 04/29/2004] [Indexed: 11/11/2022]
Abstract
During development, neurons migrate to the cortex radially from periventricular germinative zones as well as tangentially from ganglionic eminences. The vast majority of cortical neurons settle radially in the cortical plate. Neuronal migration requires an exquisite regulation of leading edge extension, nuclear translocation (nucleokinesis), and retraction of trailing processes. During the past few years, several genes and proteins have been identified that are implicated in neuronal migration. Many have been characterized by reference to known mechanisms of neuronal and non-neuronal cell migration in culture; however, probably the most interesting have been identified by gene inactivation or modification in mice and by positional cloning of brain malformation genes in humans and mice. Although it is impossible to provide a fully integrated view, some patterns clearly emerge and are the subject of this article. Specific emphasis is placed on three aspects: first, the role of the actin treadmill, with cyclic formation of filopodial and lamellipodial extensions, in relation to surface events that occur at the leading edge of radially migrating neurons; second, the regulation of microtubule dynamics, which seems to play a key role in nucleokinesis; and third, the mechanisms by which the extracellular protein Reelin regulates neuronal positioning at the end of migration.
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Affiliation(s)
- Yves Jossin
- Developmental Neurobiology Unit, University of Louvain Medical School, Brussels, Belgium.
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196
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Stolt PC, Chen Y, Liu P, Bock HH, Blacklow SC, Herz J. Phosphoinositide Binding by the Disabled-1 PTB Domain Is Necessary for Membrane Localization and Reelin Signal Transduction. J Biol Chem 2005; 280:9671-7. [PMID: 15632144 DOI: 10.1074/jbc.m413356200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Disabled-1 (Dab1) is an essential adaptor protein that functions in the Reelin signaling pathway and is required for the regulation of neuronal migration during embryonic development. Dab1 interacts with NPXY motifs in the cytoplasmic tails of the lipoprotein receptors ApoER2 and very low density lipoprotein receptor through an amino-terminal phosphotyrosine binding (PTB) domain. Binding of Reelin to these receptors leads to tyrosine phosphorylation of Dab1 and the initiation of a signaling cascade that results in remodeling of the cytoskeleton. Structural and biochemical studies of the Dab1 PTB domain have demonstrated that this domain binds to both the NPXY peptide motif in the lipoprotein receptor tails as well as to the head group of phosphoinositide 4,5-P2 through energetically independent mechanisms. Here we have investigated how phosphoinositide binding by the Dab1 PTB domain influences Reelin signal transduction. Our findings in cultured primary neurons that have been transduced with lentiviral constructs expressing mutant Dab1 forms reveal that phosphoinositide binding by the Dab1 PTB domain is necessary for proper membrane localization of Dab1 and for effective transduction of a Reelin signal.
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Affiliation(s)
- Peggy C Stolt
- Department of Pathology, Harvard Medical School, Brigham and Womens' Hospital, Boston, Massachusetts 02115, USA.
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197
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Abstract
Reelin glycoprotein is a secretory serine protease with dual roles in mammalian brain: embryologically, it guides neurons and radial glial cells to their corrected positions in the developing brain; in adult brain, Reelin is involved in a signaling pathway which underlies neurotransmission, memory formation and synaptic plasticity. Disruption of Reelin signaling pathway by mutations and selective hypermethylation of the Reln gene promoter or following various pre- or postnatal insults may lead to cognitive deficits present in neuropsychiatric disorders like autism or schizophrenia.
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Affiliation(s)
- S H Fatemi
- Division of Neuroscience Research, Department of Psychiatry, University of Minnesota Medical School, 420 Delaware Street, Minneapolis, MN 55455, USA.
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198
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Morimura T, Hattori M, Ogawa M, Mikoshiba K. Disabled1 regulates the intracellular trafficking of reelin receptors. J Biol Chem 2005; 280:16901-8. [PMID: 15718228 DOI: 10.1074/jbc.m409048200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reelin is a huge secreted protein that controls proper laminar formation in the developing brain. It is generally believed that tyrosine phosphorylation of Disabled1 (Dab1) by Src family tyrosine kinases is the most critical downstream event in Reelin signaling. The receptors for Reelin belong to the low density lipoprotein receptor family, most of whose members undergo regulated intracellular trafficking. In this study, we propose novel roles for Dab1 in Reelin signaling. We first demonstrated that cell surface expression of Reelin receptors was decreased in Dab1-deficient neurons. In heterologous cells, Dab1 enhanced cell surface expression of Reelin receptors, and this effect was mediated by direct interaction with the receptors. Moreover, Dab1 did not stably associate with the receptors at the plasma membrane in the resting state. When Reelin was added to primary cortical neurons, Dab1 was recruited to the receptors, and its tyrosine residues were phosphorylated. Although Reelin and Dab1 colocalized well shortly after the addition of Reelin, Dab1 was no longer associated with internalized Reelin. When Src family tyrosine kinases were inhibited, internalization of Reelin was severely abrogated, and Reelin colocalized with Dab1 near the plasma membrane for a prolonged period. Taken together, these results indicate that Dab1 regulates both cell surface expression and internalization of Reelin receptors, and these regulations may play a role in correct laminar formation in the developing brain.
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Affiliation(s)
- Toshifumi Morimura
- Division of Molecular Neurobiology, Department of Basic Medical Science, the Institute of Medical Science, the University of Tokyo, 4-6-1 Shirokanedai, Minato-ku 108-8639, Japan.
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199
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Stoothoff WH, Johnson GVW. Tau phosphorylation: physiological and pathological consequences. Biochim Biophys Acta Mol Basis Dis 2005; 1739:280-97. [PMID: 15615646 DOI: 10.1016/j.bbadis.2004.06.017] [Citation(s) in RCA: 308] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Accepted: 06/02/2004] [Indexed: 11/24/2022]
Abstract
The microtubule-associated protein tau, abundant in neurons, has gained notoriety due to the fact that it is deposited in cells as fibrillar lesions in numerous neurodegenerative diseases, and most notably Alzheimer's disease. Regulation of microtubule dynamics is the most well-recognized function of tau, but it is becoming increasingly evident that tau plays additional roles in the cell. The functions of tau are regulated by site-specific phosphorylation events, which if dysregulated, as they are in the disease state, result in tau dysfunction and mislocalization, which is potentially followed by tau polymerization, neuronal dysfunction and death. Given the increasing evidence that a disruption in the normal phosphorylation state of tau plays a key role in the pathogenic events that occur in Alzheimer's disease and other neurodegenerative conditions, it is of crucial importance that the protein kinases and phosphatases that regulate tau phosphorylation in vivo as well as the signaling cascades that regulate them be identified. This review focuses on recent literature pertaining to the regulation of tau phosphorylation and function in cell culture and animal model systems, and the role that a dysregulation of tau phosphorylation may play in the neuronal dysfunction and death that occur in neurodegenerative diseases that have tau pathology.
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Affiliation(s)
- William H Stoothoff
- Department of Psychiatry, School of Medicine, University of Alabama at Birmingham, 1061 Sparks Center, 1720 7th Avenue South, Birmingham, AL 35294-0017, USA
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200
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Stokely ME, Yorio T, King MA. Endothelin-1 modulates anterograde fast axonal transport in the central nervous system. J Neurosci Res 2005; 79:598-607. [PMID: 15678512 DOI: 10.1002/jnr.20383] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Anterograde fast axonal transport (FAxT) maintains synaptic function and provides materials necessary for neuronal survival. Localized changes in FAxT are associated with a variety of central nervous system (CNS) neuropathies, where they may contribute to inappropriate remodeling, a process more appropriately involved in synaptic plasticity and development. In some cases, developmental remodeling is regulated by localized secretion of endothelins (ETs), neuroinflammatory peptides that are also pathologically elevated in cases of neurologic disease, CNS injury, or ischemia. To investigate the potential role of ETs in these processes, we decided to test whether locally elevated endothelin-1 (ET-1) modulates FAxT in adult CNS tissues. We used the established in vivo rat optic nerve model and a novel ex vivo rat hippocampal slice model to test this hypothesis. In vivo, exogenously elevated vitreal ET-1 significantly affected protein composition of FAxT-cargos as well as the abundance and peak delivery times for metabolically-labeled proteins that were transported into the optic nerve. Proteins with molecular weights of 139, 118, 89, 80, 64, 59, 51, 45, 42, 37, and 25 kDa were evaluated at injection-sacrifice intervals (ISIs) of 24, 28, 32, and 36 hr. In acute hippocampal slices maintained on nonvascular supplies of glucose and oxygen, ET-1 significantly decreased the distance traveled along the Schaffer collateral tract by nonmetabolically-labeled lipid rafts at 5 and 10 min after pulse-labeling. In both models, ET-1 significantly affected transport or targeted delivery of FaxT-cargos, suggesting that ET-1 has the potential to modulate FAxT in adult CNS tissues.
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Affiliation(s)
- Martha E Stokely
- Department of Neuroscience, University of Florida at Gainesville, Gainesville, Florida 32610, USA.
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