601
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Ma T, Klann E. Amyloid β: linking synaptic plasticity failure to memory disruption in Alzheimer's disease. J Neurochem 2011; 120 Suppl 1:140-148. [PMID: 22122128 DOI: 10.1111/j.1471-4159.2011.07506.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mounting evidence suggests that amyloid beta-induced impairments in synaptic plasticity that is accompanied by cognitive decline and dementia represent key pathogenic steps of Alzheimer's disease. In this study, we review recent advances in the study of the molecular and cellular mechanisms underlying Alzheimer's disease-associated synaptic dysfunction and memory deficits, and how these mechanisms could provide novel avenues for therapeutic intervention to treat this devastating neurodegenerative disease.
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Affiliation(s)
- Tao Ma
- Center for Neural Science, New York University, New York, New York, USA
| | - Eric Klann
- Center for Neural Science, New York University, New York, New York, USA
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602
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Kim YT, Hur EM, Snider WD, Zhou FQ. Role of GSK3 Signaling in Neuronal Morphogenesis. Front Mol Neurosci 2011; 4:48. [PMID: 22131966 PMCID: PMC3222852 DOI: 10.3389/fnmol.2011.00048] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 11/06/2011] [Indexed: 01/28/2023] Open
Abstract
Glycogen synthase kinase 3 (GSK3) is emerging as a key regulator of several aspects of neuronal morphogenesis including neuronal polarization, axon growth, and axon branching. Multiple signaling pathways have been identified that control neuronal polarization, including PI3K, Rho-GTPases, Par3/6, TSC–mTOR, and PKA–LKB1. However, how these pathways are coordinated is not clear. As GSK3 signaling exhibits crosstalk with each of these pathways it has the potential to integrate these polarity signals in the control neuronal polarization. After neurons establish polarity, GSK3 acts as an important signaling mediator in the regulation of axon extension and axon branching by transducing upstream signaling to reorganization of the axonal cytoskeleton, especially microtubules. Here we review the roles of GSK3 signaling in neuronal morphogenesis and discuss the underlying molecular mechanisms.
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Affiliation(s)
- Yun Tai Kim
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine Baltimore, MD, USA
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603
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Gómez-Sintes R, Hernández F, Lucas JJ, Avila J. GSK-3 Mouse Models to Study Neuronal Apoptosis and Neurodegeneration. Front Mol Neurosci 2011; 4:45. [PMID: 22110426 PMCID: PMC3217194 DOI: 10.3389/fnmol.2011.00045] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 10/31/2011] [Indexed: 11/19/2022] Open
Abstract
Increased GSK-3 activity is believed to contribute to the etiology of chronic disorders like Alzheimer’s disease (AD), schizophrenia, diabetes, and some types of cancer, thus supporting therapeutic potential of GSK-3 inhibitors. Numerous mouse models with modified GSK-3 have been generated in order to study the physiology of GSK-3, its implication in diverse pathologies and the potential effect of GSK-3 inhibitors. In this review we have focused on the relevance of these mouse models for the study of the role of GSK-3 in apoptosis. GSK-3 is involved in two apoptotic pathways, intrinsic and extrinsic pathways, and plays opposite roles depending on the apoptotic signaling process that is activated. It promotes cell death when acting through intrinsic pathway and plays an anti-apoptotic role if the extrinsic pathway is occurring. It is important to dissect this duality since, among the diseases in which GSK-3 is involved, excessive cell death is crucial in some illnesses like neurodegenerative diseases, while a deficient apoptosis is occurring in others such as cancer or autoimmune diseases. The clinical application of a classical GSK-3 inhibitor, lithium, is limited by its toxic consequences, including motor side effects. Recently, the mechanism leading to activation of apoptosis following chronic lithium administration has been described. Understanding this mechanism could help to minimize side effects and to improve application of GSK-3 inhibitors to the treatment of AD and to extend the application to other diseases.
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Affiliation(s)
- Raquel Gómez-Sintes
- Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid Madrid, Spain
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604
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Hur EM, Saijilafu, Lee BD, Kim SJ, Xu WL, Zhou FQ. GSK3 controls axon growth via CLASP-mediated regulation of growth cone microtubules. Genes Dev 2011; 25:1968-81. [PMID: 21937714 DOI: 10.1101/gad.17015911] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Suppression of glycogen synthase kinase 3 (GSK3) activity in neurons yields pleiotropic outcomes, causing both axon growth promotion and inhibition. Previous studies have suggested that specific GSK3 substrates, such as adenomatous polyposis coli (APC) and collapsin response mediator protein 2 (CRMP2), support axon growth by regulating the stability of axonal microtubules (MTs), but the substrate(s) and mechanisms conveying axon growth inhibition remain elusive. Here we show that CLIP (cytoplasmic linker protein)-associated protein (CLASP), originally identified as a MT plus end-binding protein, displays both plus end-binding and lattice-binding activities in nerve growth cones, and reveal that the two MT-binding activities regulate axon growth in an opposing manner: The lattice-binding activity mediates axon growth inhibition induced by suppression of GSK3 activity via preventing MT protrusion into the growth cone periphery, whereas the plus end-binding property supports axon extension via stabilizing the growing ends of axonal MTs. We propose a model in which CLASP transduces GSK3 activity levels to differentially control axon growth by coordinating the stability and configuration of growth cone MTs.
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Affiliation(s)
- Eun-Mi Hur
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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605
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Guo W, Murthy AC, Zhang L, Johnson EB, Schaller EG, Allan AM, Zhao X. Inhibition of GSK3β improves hippocampus-dependent learning and rescues neurogenesis in a mouse model of fragile X syndrome. Hum Mol Genet 2011; 21:681-91. [PMID: 22048960 DOI: 10.1093/hmg/ddr501] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fragile X syndrome (FXS), a common inherited form of intellectual disability with learning deficits, results from a loss of fragile X mental retardation protein (FMRP). Despite extensive research, treatment options for FXS remain limited. Since FMRP is known to play an important role in adult hippocampal neurogenesis and hippocampus-dependent learning and FMRP regulates the adult neural stem cell fate through the translational regulation of glycogen synthase kinase 3β (GSK3β), we investigated the effects of a GSK3β inhibitor, SB216763, on Fmr1 knockout mice (Fmr1 KO). We found that the inhibition of GSK3β could reverse the hippocampus-dependent learning deficits and rescue adult hippocampal neurogenesis at multiple stages in Fmr1 KO mice. Our results point to GSK3β inhibition as a potential treatment for the learning deficits seen in FXS.
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Affiliation(s)
- Weixiang Guo
- Waisman Center and Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
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606
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Eldar-Finkelman H, Martinez A. GSK-3 Inhibitors: Preclinical and Clinical Focus on CNS. Front Mol Neurosci 2011; 4:32. [PMID: 22065134 PMCID: PMC3204427 DOI: 10.3389/fnmol.2011.00032] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 09/29/2011] [Indexed: 12/24/2022] Open
Abstract
Inhibiting glycogen synthase kinase-3 (GSK-3) activity via pharmacological intervention has become an important strategy for treating neurodegenerative and psychiatric disorders. The known GSK-3 inhibitors are of diverse chemotypes and mechanisms of action and include compounds isolated from natural sources, cations, synthetic small-molecule ATP-competitive inhibitors, non-ATP-competitive inhibitors, and substrate-competitive inhibitors. Here we describe the variety of GSK-3 inhibitors with a specific emphasis on their biological activities in neurons and neurological disorders. We further highlight our current progress in the development of non-ATP-competitive inhibitors of GSK-3. The available data raise the hope that one or more of these drug design approaches will prove successful at stabilizing or even reversing the aberrant neuropathology and cognitive deficits of certain central nervous system disorders.
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Affiliation(s)
- Hagit Eldar-Finkelman
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University Tel Aviv, Israel
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607
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Bedner P, Steinhäuser C, Theis M. Functional redundancy and compensation among members of gap junction protein families? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1971-84. [PMID: 22044799 DOI: 10.1016/j.bbamem.2011.10.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 10/08/2011] [Accepted: 10/17/2011] [Indexed: 12/15/2022]
Abstract
Gap junctions are intercellular conduits for small molecules made up by protein subunits called connexins. A large number of connexin genes were found in mouse and man, and most cell types express several connexins, lending support to the view that redundancy and compensation among family members exist. This review gives an overview of the current knowledge on redundancy and functional compensation - or lack thereof. It takes into account the different properties of connexin subunits which comprise gap junctional intercellular channels, but also the compatibility of connexins in gap junctions. Most insight has been gained by the investigation of mice deficient for one or more connexins and transgenic mice with functional replacement of one connexin gene by another. Most single deficient mice show phenotypical alterations limited to critical developmental time points or to specific organs and tissues, while mice doubly deficient for connexins expressed in the same cell type usually show more severe phenotypical alterations. Replacement of a connexin by another connexin in some cases gave rise to rescue of phenotypical alterations of connexin deficiencies, which were restricted to specific tissues. In many tissues, connexin substitution did not restore phenotypical alterations of connexin deficiencies, indicating that connexins are specialized in function. In some cases, fatal consequences arose from the replacement. The current consensus gained from such studies is that redundancy and compensation among connexins exists at least to a limited extent. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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608
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Colleoni S, Galli C, Gaspar JA, Meganathan K, Jagtap S, Hescheler J, Sachinidis A, Lazzari G. Development of a neural teratogenicity test based on human embryonic stem cells: response to retinoic acid exposure. Toxicol Sci 2011; 124:370-7. [PMID: 21934132 DOI: 10.1093/toxsci/kfr245] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The aim of this study was the development of an alternative testing method based on human embryonic stem cells for prenatal developmental toxicity with particular emphasis on early neural development. To this purpose, we designed an in vitro protocol based on the generation of neural rosettes, representing the in vitro counterpart of the developing neural plate and neural tube, and we challenged this complex cell model with retinoic acid (RA), a well-known teratogenic agent. The cells were exposed to different concentrations of RA during the process of rosettes formation. Morphological and molecular parameters were evaluated in treated as compared with untreated cells to detect both cytotoxicity and specific neural toxicity. Transcriptomic analysis was performed with microarray Affymetrix platform and validated by quantitative real-time PCR for genes relevant to early neural development such as HoxA1, HoxA3, HoxB1, HoxB4, FoxA2, FoxC1, Otx2, and Pax7. The results obtained demonstrated that neural rosette forming cells respond to RA with clear concentration-dependent morphological, and gene expression changes remarkably similar to those induced in vivo, in the developing neural tube, by RA exposure. This strict correspondence indicates that the neural rosette protocol described is capable of detecting specific teratogenic mechanisms causing perturbations of early neural development and therefore represents a promising alternative test for human prenatal developmental toxicity.
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Affiliation(s)
- Silvia Colleoni
- Avantea, Laboratory of Reproductive Technologies, 26100 Cremona, Italy.
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609
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Polter AM, Yang S, Jope RS, Li X. Functional significance of glycogen synthase kinase-3 regulation by serotonin. Cell Signal 2011; 24:265-71. [PMID: 21946431 DOI: 10.1016/j.cellsig.2011.09.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 09/09/2011] [Indexed: 12/21/2022]
Abstract
Serotonin modulates brain physiology and behavior and has major roles in brain diseases involving abnormal mood and cognition. Enhancing brain serotonin has been found to regulate glycogen synthase Kinase-3 (GSK3), but the signaling mechanism and functional significance of this regulation remain to be determined. In this study, we tested the signaling mechanism mediating 5-HT1A receptor-regulated GSK3 in the hippocampus. Using mutant GSK3 knock-in mice, we also tested the role of GSK3 in the behavioral effects of 5-HT1A receptors and the serotonin reuptake inhibitor fluoxetine. The results showed that activation of 5-HT1A receptors by 8-hydroxy-N,N-dipropyl-2-aminotetralin (8-OH-DPAT) increased phosphorylation of the N-terminal serine of both GSK3α and GSK3β in several areas of the hippocampus. The effect of 8-OH-DPAT was accompanied by an increase in the active phosphorylation of Akt, and was blocked by LY294002, an inhibitor of phosphoinositide 3-kinases (PI3K). Phosphorylation of GSK3β, but not GSK3α, was necessary for 5-HT1A receptors to suppress the hippocampus-associated contextual fear learning. Furthermore, acute fluoxetine treatment up-regulated both phospho-Ser21-GSK3α and phospho-Ser9-GSK3β in the hippocampus. Blocking phosphorylation of GSK3α and GSK3β diminished the anti-immobility effect of fluoxetine treatment in the forced swim test, wherein the effect of GSK3β was more prominent. These results together suggest that PI3K/Akt is a signaling mechanism mediating the GSK3-regulating effect of 5-HT1A receptors in the hippocampus, and regulation of GSK3 is an important intermediate signaling process in the behavioral functions of 5-HT1A receptors and fluoxetine.
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Affiliation(s)
- Abigail M Polter
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
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610
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Neasta J, Ben Hamida S, Yowell QV, Carnicella S, Ron D. AKT signaling pathway in the nucleus accumbens mediates excessive alcohol drinking behaviors. Biol Psychiatry 2011; 70:575-82. [PMID: 21549353 PMCID: PMC3228847 DOI: 10.1016/j.biopsych.2011.03.019] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 03/08/2011] [Accepted: 03/10/2011] [Indexed: 12/31/2022]
Abstract
BACKGROUND Neuroadaptations within the nucleus accumbens (NAc) have been implicated in molecular mechanisms underlying the development and/or maintenance of alcohol abuse disorders. We recently reported that the activation of mammalian target of rapamycin complex 1 (mTORC1) signaling pathway in the NAc of rodents, after exposure to alcohol, contributes to alcohol drinking behaviors. The kinase AKT is a main upstream activator of the mTORC1 pathway. We therefore hypothesized that the activation of AKT in the NAc in response to alcohol exposure plays an important role in mechanisms that underlie excessive alcohol consumption. METHODS Western blot analysis was used to assess the phosphorylation levels of enzymes. Acute exposure of mice to alcohol was achieved by the administration of 2 g/kg alcohol intraperitoneally (i.p.). Two-bottle choice and operant self-administration procedures were used to assess drinking behaviors in rats. RESULTS We found that acute systemic administration of alcohol and recurring cycles of excessive voluntary consumption of alcohol and withdrawal result in the activation of AKT signaling in the NAc of rodents. We show that inhibition of AKT or its upstream activator, phosphatidylinositol-3-kinase (PI3K), within the NAc of rats attenuates binge drinking as well as alcohol but not sucrose operant self-administration. CONCLUSIONS Our results suggest that the activation of the AKT pathway in the NAc in response to alcohol exposure is an important contributor to the molecular mechanisms underlying alcohol-drinking behaviors. AKT signaling pathway inhibitors are therefore potential candidates for drug development for the treatment of alcohol use and abuse disorders.
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Affiliation(s)
- Jérémie Neasta
- Ernest Gallo Research Center, Department of Neurology, University of California, San Francisco, 5858 Horton street, suite 200, Emeryville, CA 94608
| | - Sami Ben Hamida
- Ernest Gallo Research Center, Department of Neurology, University of California, San Francisco, 5858 Horton street, suite 200, Emeryville, CA 94608
| | - Quinn V. Yowell
- Ernest Gallo Research Center, Department of Neurology, University of California, San Francisco, 5858 Horton street, suite 200, Emeryville, CA 94608
| | - Sebastien Carnicella
- Ernest Gallo Research Center, Department of Neurology, University of California, San Francisco, 5858 Horton street, suite 200, Emeryville, CA 94608
| | - Dorit Ron
- Ernest Gallo Research Center, Department of Neurology, University of California, San Francisco, 5858 Horton street, suite 200, Emeryville, CA 94608,To whom correspondence should be addressed. Dorit Ron, Ph.D., 5858 Horton St., Suite 200, Emeryville, CA, 94608, Tel: 510-985-3150, Fax: 510-985-3101,
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611
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Kremer A, Louis JV, Jaworski T, Van Leuven F. GSK3 and Alzheimer's Disease: Facts and Fiction…. Front Mol Neurosci 2011; 4:17. [PMID: 21904524 PMCID: PMC3162188 DOI: 10.3389/fnmol.2011.00017] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 08/08/2011] [Indexed: 12/31/2022] Open
Abstract
The physiological functions and pathological roles of the Glycogen synthase kinase-type 3 (GSK3) kinases in peripheral and central systems are diverse and complex, and therefore hard to unravel in molecular detail in vivo. Our assignment to review and discuss available data to clarify the actual position of these kinases in the pathology of Alzheimer’s dementia (AD) was both ambitious and easy. On the one hand, numerous studies are available in isolated, recombinant, or cell-based systems, which have resulted in very diverse data-sets that are hardly informative for the brain in vivo. At the other extreme, reliable, and relevant models for the role of GSK3 in CNS are rare, if not lacking. Moreover, (too) many in vivo studies used Li+ as “specific” inhibitor of GSK3, which is factually not valid because lithium ions are neither specific nor potent inhibitors of GSK3 in vivo. More specific pharmacological inhibitors of GSK3 have met with considerable problems, and are reviewed by others in this issue or elsewhere. We concentrate here on AD-related aspects of GSK3 in brain in vivo, mainly studied in transgenic mice and highlight some of the more important issues, among many remaining: activation of GSK3 by amyloid, phosphorylation of protein tau, effects on or interference with synaptic activity, differentiation between both GSK3 isoforms. These relate directly to brain function, and brain dysfunction in AD, and are to be resolved if we want to understand the molecular pathology of this dreadful disease.
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Affiliation(s)
- Anna Kremer
- Experimental Genetics Group - LEGTEGG, Department Human Genetics KULeuven, Leuven, Belgium
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612
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Pedrosa E, Sandler V, Shah A, Carroll R, Chang C, Rockowitz S, Guo X, Zheng D, Lachman HM. Development of patient-specific neurons in schizophrenia using induced pluripotent stem cells. J Neurogenet 2011; 25:88-103. [PMID: 21797804 DOI: 10.3109/01677063.2011.597908] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Induced pluripotent stem cell (iPSC) technology has the potential to transform regenerative medicine. It also offers a powerful tool for establishing in vitro models of disease, in particular, for neuropsychiatric disorders where live human neurons are essentially impossible to procure. Using iPSCs derived from three schizophrenia (SZ) patients, one of whom has 22q11.2del (velocardiofacial syndrome; VCFS), the authors developed a culture system to study SZ on a molecular and cellular level. SZ iPSCs were differentiated into functional, primarily glutamatergic neurons that were able to fire action potentials after ∼8 weeks in culture. Early differentiating neurons expressed a number of transcription factors/chromatin remodeling proteins and synaptic proteins relevant to SZ pathogenesis, including ZNF804A, RELN, CNTNAP2, CTNNA2, SMARCA2, and NRXN1. Although a small number of lines were developed in this preliminary study, the SZ line containing 22q11.2del showed a significant delay in the reduction of endogenous OCT4 and NANOG expression that normally occurs during differentiation. Constitutive expression of OCT4 has been observed in Dgcr8-deficient mouse embryonic stem cells (mESCs); DGCR8 maps to the 22q11.2-deleted region. These findings demonstrate that the method of inducing neural differentiation employed is useful for disease modeling in SZ and that the transition of iPSCs with 22q11.2 deletions towards a differentiated state may be marked by subtle changes in expression of pluripotency-associated genes.
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Affiliation(s)
- Erika Pedrosa
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, New York 10416, USA
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613
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Misztal K, Wisniewska MB, Ambrozkiewicz M, Nagalski A, Kuznicki J. WNT protein-independent constitutive nuclear localization of beta-catenin protein and its low degradation rate in thalamic neurons. J Biol Chem 2011; 286:31781-8. [PMID: 21757747 DOI: 10.1074/jbc.m111.229666] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nuclear localization of β-catenin is a hallmark of canonical Wnt signaling, a pathway that plays a crucial role in brain development and the neurogenesis of the adult brain. We recently showed that β-catenin accumulates specifically in mature thalamic neurons, where it regulates the expression of the Ca(v)3.1 voltage-gated calcium channel gene. Here, we investigated the mechanisms underlying β-catenin accumulation in thalamic neurons. We report that a lack of soluble factors produced either by glia or cortical neurons does not impair nuclear β-catenin accumulation in thalamic neurons. We next found that the number of thalamic neurons with β-catenin nuclear localization did not change when the Wnt/Dishevelled signaling pathway was inhibited by Dickkopf1 or a dominant negative mutant of Dishevelled3. These results suggest a WNT-independent cell-autonomous mechanism. We found that the protein levels of APC, AXIN1, and GSK3β, components of the β-catenin degradation complex, were lower in the thalamus than in the cortex of the adult rat brain. Reduced levels of these proteins were also observed in cultured thalamic neurons compared with cortical cultures. Finally, pulse-chase experiments confirmed that cytoplasmic β-catenin turnover was slower in thalamic neurons than in cortical neurons. Altogether, our data indicate that the nuclear localization of β-catenin in thalamic neurons is their cell-intrinsic feature, which was WNT-independent but associated with low levels of proteins involved in β-catenin labeling for ubiquitination and subsequent degradation.
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Affiliation(s)
- Katarzyna Misztal
- Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland
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614
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Matamales M, Girault JA. Signaling from the cytoplasm to the nucleus in striatal medium-sized spiny neurons. Front Neuroanat 2011; 5:37. [PMID: 21779236 PMCID: PMC3133824 DOI: 10.3389/fnana.2011.00037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Accepted: 06/13/2011] [Indexed: 12/13/2022] Open
Abstract
Striatal medium-sized spiny neurons (MSNs) receive massive glutamate inputs from the cerebral cortex and thalamus and are a major target of dopamine projections. Interaction between glutamate and dopamine signaling is crucial for the control of movement and reward-driven learning, and its alterations are implicated in several neuropsychiatric disorders including Parkinson's disease and drug addiction. Long-lasting forms of synaptic plasticity are thought to depend on transcription of gene products that alter the structure and/or function of neurons. Although multiple signal transduction pathways regulate transcription, little is known about signal transmission between the cytoplasm and the nucleus of striatal neurons and its regulation. Here we review the current knowledge of the signaling cascades that target the nucleus of MSNs, most of which are activated by cAMP and/or Ca(2+). We outline the mechanisms by which signals originating at the plasma membrane and amplified in the cytoplasm are relayed to the nucleus, through the regulation of several protein kinases and phosphatases and transport through the nuclear pore. We also summarize the identified mechanisms of transcription regulation and chromatin remodeling in MSNs that appear to be important for behavioral adaptations, and discuss their relationships with epigenetic regulation.
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Affiliation(s)
- Miriam Matamales
- UMR-S 839, InsermParis, France
- Université Pierre et Marie CurieParis, France
- Institut du Fer à MoulinParis, France
| | - Jean-Antoine Girault
- UMR-S 839, InsermParis, France
- Université Pierre et Marie CurieParis, France
- Institut du Fer à MoulinParis, France
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615
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Kozikowski AP, Gunosewoyo H, Guo S, Gaisina IN, Walter RL, Ketcherside A, McClung CA, Mesecar AD, Caldarone B. Identification of a glycogen synthase kinase-3β inhibitor that attenuates hyperactivity in CLOCK mutant mice. ChemMedChem 2011; 6:1593-602. [PMID: 21732538 DOI: 10.1002/cmdc.201100188] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Indexed: 11/08/2022]
Abstract
Bipolar disorder is characterized by a cycle of mania and depression, which affects approximately 5 million people in the United States. Current treatment regimes include the so-called "mood-stabilizing drugs", such as lithium and valproate that are relatively dated drugs with various known side effects. Glycogen synthase kinase-3β (GSK-3β) plays a central role in regulating circadian rhythms, and lithium is known to be a direct inhibitor of GSK-3β. We designed a series of second generation benzofuran-3-yl-(indol-3-yl)maleimides containing a piperidine ring that possess IC₅₀ values in the range of 4 to 680 nM against human GSK-3β. One of these compounds exhibits reasonable kinase selectivity and promising preliminary absorption, distribution, metabolism, and excretion (ADME) data. The administration of this compound at doses of 10 to 25 mg kg⁻¹ resulted in the attenuation of hyperactivity in amphetamine/chlordiazepoxide-induced manic-like mice together with enhancement of prepulse inhibition, similar to the effects found for valproate (400 mg kg⁻¹) and the antipsychotic haloperidol (1 mg kg⁻¹). We also tested this compound in mice carrying a mutation in the central transcriptional activator of molecular rhythms, the CLOCK gene, and found that the same compound attenuates locomotor hyperactivity in response to novelty. This study further demonstrates the use of inhibitors of GSK-3β in the treatment of manic episodes of bipolar/mood disorders, thus further validating GSK-3β as a relevant therapeutic target in the identification of new therapies for bipolar patients.
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Affiliation(s)
- Alan P Kozikowski
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA.
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616
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Genetic regulation of Nrxn1 [corrected] expression: an integrative cross-species analysis of schizophrenia candidate genes. Transl Psychiatry 2011; 1:e25. [PMID: 22832527 PMCID: PMC3309521 DOI: 10.1038/tp.2011.24] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Neurexin 1 (NRXN1) is a large presynaptic transmembrane protein that has complex and variable patterns of expression in the brain. Sequence variants in NRXN1 are associated with differences in cognition, and with schizophrenia and autism. The murine Nrxn1 gene is also highly polymorphic and is associated with significant variation in expression that is under strong genetic control. Here, we use co-expression analysis, high coverage genomic sequence, and expression quantitative trait locus (eQTL) mapping to study the regulation of this gene in the brain. We profiled a family of 72 isogenic progeny strains of a cross between C57BL/6J and DBA/2J (the BXD family) using exon arrays and massively parallel RNA sequencing. Expression of most Nrxn1 exons have high genetic correlation (r>0.6) because of the segregation of a common trans eQTL on chromosome (Chr) 8 and a common cis eQTL on Chr 17. These two loci are also linked to murine phenotypes relevant to schizophrenia and to a novel human schizophrenia candidate gene with high neuronal expression (Pleckstrin and Sec7 domain containing 3). In both human and mice, NRXN1 is co-expressed with numerous synaptic and cell signaling genes, and known schizophrenia candidates. Cross-species co-expression and protein interaction network analyses identified glycogen synthase kinase 3 beta (GSK3B) as one of the most consistent and conserved covariates of NRXN1. By using the Molecular Genetics of Schizophrenia data set, we were able to test and confirm that markers in NRXN1 and GSK3B have epistatic interactions in human populations that can jointly modulate risk of schizophrenia.
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617
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Martinez A, Gil C, Perez DI. Glycogen synthase kinase 3 inhibitors in the next horizon for Alzheimer's disease treatment. Int J Alzheimers Dis 2011; 2011:280502. [PMID: 21760986 PMCID: PMC3132520 DOI: 10.4061/2011/280502] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 05/03/2011] [Indexed: 11/23/2022] Open
Abstract
Glycogen synthase kinase 3 (GSK-3), a proline/serine protein kinase ubiquitously expressed and involved in many cellular signaling pathways, plays a key role in the pathogenesis of Alzheimer's disease (AD) being probably the link between β-amyloid and tau pathology. A great effort has recently been done in the discovery and development of different new molecules, of synthetic and natural origin, able to inhibit this enzyme, and several kinetics mechanisms of binding have been described. The small molecule called tideglusib belonging to the thiadiazolidindione family is currently on phase IIb clinical trials for AD. The potential risks and benefits of this new kind of disease modifying drugs for the future therapy of AD are discussed in this paper.
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Affiliation(s)
- Ana Martinez
- Instituto de Química Médica, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
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618
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Pal S, Gupta R, Kim H, Wickramasinghe P, Baubet V, Showe LC, Dahmane N, Davuluri RV. Alternative transcription exceeds alternative splicing in generating the transcriptome diversity of cerebellar development. Genome Res 2011; 21:1260-72. [PMID: 21712398 DOI: 10.1101/gr.120535.111] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Despite our growing knowledge that many mammalian genes generate multiple transcript variants that may encode functionally distinct protein isoforms, the transcriptomes of various tissues and their developmental stages are poorly defined. Identifying the transcriptome and its regulation in a cell/tissue is the key to deciphering the cell/tissue-specific functions of a gene. We built a genome-wide inventory of noncoding and protein-coding transcripts (transcriptomes), their promoters (promoteromes) and histone modification states (epigenomes) for developing, and adult cerebella using integrative massive-parallel sequencing and bioinformatics approach. The data consists of 61,525 (12,796 novel) distinct mRNAs transcribed by 29,589 (4792 novel) promoters corresponding to 15,669 protein-coding and 7624 noncoding genes. Importantly, our results show that the transcript variants from a gene are predominantly generated using alternative transcriptional rather than splicing mechanisms, highlighting alternative promoters and transcriptional terminations as major sources of transcriptome diversity. Moreover, H3K4me3, and not H3K27me3, defined the use of alternative promoters, and we identified a combinatorial role of H3K4me3 and H3K27me3 in regulating the expression of transcripts, including transcript variants of a gene during development. We observed a strong bias of both H3K4me3 and H3K27me3 for CpG-rich promoters and an exponential relationship between their enrichment and corresponding transcript expression. Furthermore, the majority of genes associated with neurological diseases expressed multiple transcripts through alternative promoters, and we demonstrated aberrant use of alternative promoters in medulloblastoma, cancer arising in the cerebellum. The transcriptomes of developing and adult cerebella presented in this study emphasize the importance of analyzing gene regulation and function at the isoform level.
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Affiliation(s)
- Sharmistha Pal
- Center for Systems and Computational Biology, The Wistar Institute, Philadelphia, Pennsylvania 19019, USA
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619
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Eichhoff OM, Weeraratna A, Zipser MC, Denat L, Widmer DS, Xu M, Kriegl L, Kirchner T, Larue L, Dummer R, Hoek KS. Differential LEF1 and TCF4 expression is involved in melanoma cell phenotype switching. Pigment Cell Melanoma Res 2011; 24:631-42. [PMID: 21599871 DOI: 10.1111/j.1755-148x.2011.00871.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent observations suggest that melanoma cells drive disease progression by switching back and forth between phenotypic states of proliferation and invasion. Phenotype switching has been linked to changes in Wnt signalling, and we therefore looked for cell phenotype-specific differences in the levels and activity of β-catenin and its LEF/TCF co-factors. We found that while cytosolic β-catenin distribution is phenotype-specific (membrane-associated in proliferative cells and cytosolic in invasive cells), its nuclear distribution and activity is not. Instead, the expression patterns of two β-catenin co-factors, LEF1 and TCF4, are both phenotype-specific and inversely correlated. LEF1 is preferentially expressed by differentiated/proliferative phenotype cells and TCF4 by dedifferentiated/invasive phenotype cells. Knock-down experiments confirmed that these co-factors are important for the phenotype-specific expression of M-MITF, WNT5A and other genes and that LEF1 suppresses TCF4 expression independently of β-catenin. Our data show that melanoma cell phenotype switching behaviour is regulated by differential LEF1/TCF4 activity.
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Affiliation(s)
- Ossia M Eichhoff
- Department of Dermatology, University Hospital of Zürich, Zürich, Switzerland
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620
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Lee FHF, Kaidanovich-Beilin O, Roder JC, Woodgett JR, Wong AHC. Genetic inactivation of GSK3α rescues spine deficits in Disc1-L100P mutant mice. Schizophr Res 2011; 129:74-9. [PMID: 21498050 DOI: 10.1016/j.schres.2011.03.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 03/26/2011] [Accepted: 03/29/2011] [Indexed: 02/06/2023]
Abstract
Disrupted-in-Schizophrenia 1 (DISC1), a strong candidate gene for schizophrenia and other mental disorders, regulates neurodevelopmental processes including neurogenesis, neuronal migration, neurite outgrowth and spine development. Glycogen synthase kinase-3 (GSK3) directly interacts with DISC1 and also plays a role in neurodevelopment. Recently, our group showed that the Disc1-L100P mutant protein has reduced interaction with both GSK3α and β. Genetic and pharmacological inhibition of GSK3 activity rescued behavioral abnormalities in Disc1-L100P mutant mice. However, the cellular mechanisms mediating these effects of GSK3 inhibition in Disc1 mutant mice remain unclear. We sought to investigate the effects of genetic inactivation of GSK3α on frontal cortical neuron morphology in Disc1 L100P mutant mice using Golgi staining. We found a significant decrease in dendritic length and surface area in Disc1-L100P, GSK3α null and L100P/GSK3α double mutants. Dendritic spine density was significantly reduced only in Disc1-L100P and L100P/GSK3α +/- mice when compared to wild-type littermates. There was no difference in dendritic arborization between the various genotypes. No significant rescue in dendritic length and surface area was observed in L100P/GSK3α mutants versus L100P mice, but spine density in L100P/GSK3α mice was comparable to wild-type. Neurite outgrowth and spine development abnormalities induced by Disc1 mutation may be partially corrected through GSK3α inactivation, which also normalizes behavior. However, many of the other dendritic abnormalities in the Disc1-L100P mutant mice were not corrected by GSK3α inactivation, suggesting that only some of the anatomical defects have observable behavioral effects. These findings suggest novel treatment approaches for schizophrenia, and identify a histological read-out for testing other therapeutic interventions.
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Affiliation(s)
- Frankie H F Lee
- Neuroscience Division, Centre for Addiction and Mental Health, 250 College St, Toronto, Ontario, Canada M5T 1R8
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621
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Ragot K, Delmas D, Athias A, Nury T, Baarine M, Lizard G. α-Tocopherol impairs 7-ketocholesterol-induced caspase-3-dependent apoptosis involving GSK-3 activation and Mcl-1 degradation on 158N murine oligodendrocytes. Chem Phys Lipids 2011; 164:469-78. [PMID: 21575614 DOI: 10.1016/j.chemphyslip.2011.04.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 04/27/2011] [Accepted: 04/28/2011] [Indexed: 11/30/2022]
Abstract
In important and severe neurodegenerative pathologies, 7-ketocholesterol, mainly resulting from cholesterol autoxidation, may contribute to dys- or demyelination processes. On various cell types, 7-ketocholesterol has often been shown to induce a complex mode of cell death by apoptosis associated with phospholipidosis. On 158N murine oligodendrocytes treated with 7-ketocholesterol (20 μg/mL corresponding to 50 μM, 24-48 h), the induction of a mode of cell death by apoptosis characterised by the occurrence of cells with condensed and/or fragmented nuclei, caspase activation (including caspase-3) and internucleosomal DNA fragmentation was observed. It was associated with a loss of transmembrane mitochondrial potential (ΔΨm) measured with JC-1, with a dephosphorylation of Akt and GSK3 (especially GSK3β), and with degradation of Mcl-1. With α-tocopherol (400 μM), which was capable of counteracting 7-ketocholesterol-induced apoptosis, Akt and GSK3β dephosphorylation were inhibited as well as Mcl-1 degradation. These data underline that the potential protective effects of α-tocopherol against 7-ketocholesterol-induced apoptosis do not depend on the cell line considered, and that the cascade of events (Akt/GSK3β/Mcl-1) constitutes a link between 7-ketocholesterol-induced cytoplasmic membrane dysfunctions and mitochondrial depolarisation leading to apoptosis.
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Affiliation(s)
- Kévin Ragot
- Centre de Recherche INSERM 866 (Lipides, Nutrition, Cancer)-Equipe Biochimie Métabolique et Nutritionnelle, Université de Bourgogne, Dijon, France
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622
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Koistinaho J, Malm T, Goldsteins G. Glycogen synthase kinase-3β: a mediator of inflammation in Alzheimer's disease? Int J Alzheimers Dis 2011; 2011:129753. [PMID: 21629736 PMCID: PMC3100542 DOI: 10.4061/2011/129753] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/04/2011] [Indexed: 02/03/2023] Open
Abstract
Proliferation and activation of microglial cells is a neuropathological characteristic of brain injury and neurodegeneration, including Alzheimer's disease. Microglia act as the first and main form of immune defense in the nervous system. While the primary function of microglia is to survey and maintain the cellular environment optimal for neurons in the brain parenchyma by actively scavenging the brain for damaged brain cells and foreign proteins or particles, sustained activation of microglia may result in high production of proinflammatory mediators that disturb normal brain functions and even cause neuronal injury. Glycogen synthase kinase-3β has been recently identified as a major regulator of immune system and mediates inflammatory responses in microglia. Glycogen synthase kinase-3β has been extensively investigated in connection to tau and amyloid β toxicity, whereas reports on the role of this enzyme in neuroinflammation in Alzheimer's disease are negligible. Here we review and discuss the role of glycogen synthase-3β in immune cells in the context of Alzheimer's disease pathology.
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Affiliation(s)
- Jari Koistinaho
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
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623
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Salcedo-Tello P, Ortiz-Matamoros A, Arias C. GSK3 Function in the Brain during Development, Neuronal Plasticity, and Neurodegeneration. Int J Alzheimers Dis 2011; 2011:189728. [PMID: 21660241 PMCID: PMC3109514 DOI: 10.4061/2011/189728] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 03/07/2011] [Indexed: 02/06/2023] Open
Abstract
GSK3 has diverse functions, including an important role in brain pathology. In this paper, we address the primary functions of GSK3 in development and neuroplasticity, which appear to be interrelated and to mediate age-associated neurological diseases. Specifically, GSK3 plays a pivotal role in controlling neuronal progenitor proliferation and establishment of neuronal polarity during development, and the upstream and downstream signals modulating neuronal GSK3 function affect cytoskeletal reorganization and neuroplasticity throughout the lifespan. Modulation of GSK3 in brain areas subserving cognitive function has become a major focus for treating neuropsychiatric and neurodegenerative diseases. As a crucial node that mediates a variety of neuronal processes, GSK3 is proposed to be a therapeutic target for restoration of synaptic functioning and cognition, particularly in Alzheimer's disease.
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Affiliation(s)
- Pamela Salcedo-Tello
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, AP 70-228, 04510 Ciudad de México, Mexico
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624
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Medina M, Wandosell F. Deconstructing GSK-3: The Fine Regulation of Its Activity. Int J Alzheimers Dis 2011; 2011:479249. [PMID: 21629747 PMCID: PMC3100567 DOI: 10.4061/2011/479249] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 02/28/2011] [Indexed: 01/12/2023] Open
Abstract
Glycogen synthase kinase-3 (GSK-3) unique position in modulating the function of a diverse series of proteins in combination with its association with a wide variety of human disorders has attracted significant attention to the protein both as a therapeutic target and as a means to understand the molecular basis of these disorders. GSK-3 is ubiquitously expressed and, unusually, constitutively active in resting, unstimulated cells. In mammals, GSK-3α and β are each expressed widely at both the RNA and protein levels although some tissues show preferential levels of some of the two proteins. Neither gene appears to be acutely regulated at the transcriptional level, whereas the proteins are controlled posttranslationally, largely through protein-protein interactions or by posttranslational regulation. Control of GSK-3 activity thus occurs by complex mechanisms that are each dependent upon specific signalling pathways. Furthermore, GSK-3 appears to be a cellular nexus, integrating several signalling systems, including several second messengers and a wide selection of cellular stimulants. This paper will focus on the different ways to control GSK-3 activity (phosphorylation, protein complex formation, truncation, subcellular localization, etc.), the main signalling pathways involved in its control, and its pathological deregulation.
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625
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Synaptic Wnt signaling-a contributor to major psychiatric disorders? J Neurodev Disord 2011; 3:162-74. [PMID: 21533542 PMCID: PMC3180925 DOI: 10.1007/s11689-011-9083-6] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 04/05/2011] [Indexed: 02/08/2023] Open
Abstract
Wnt signaling is a key pathway that helps organize development of the nervous system. It influences cell proliferation, cell fate, and cell migration in the developing nervous system, as well as axon guidance, dendrite development, and synapse formation. Given this wide range of roles, dysregulation of Wnt signaling could have any number of deleterious effects on neural development and thereby contribute in many different ways to the pathogenesis of neurodevelopmental disorders. Some major psychiatric disorders, including schizophrenia, bipolar disorder, and autism spectrum disorders, are coming to be understood as subtle dysregulations of nervous system development, particularly of synapse formation and maintenance. This review will therefore touch on the importance of Wnt signaling to neurodevelopment generally, while focusing on accumulating evidence for a synaptic role of Wnt signaling. These observations will be discussed in the context of current understanding of the neurodevelopmental bases of major psychiatric diseases, spotlighting schizophrenia, bipolar disorder, and autism spectrum disorder. In short, this review will focus on the potential role of synapse formation and maintenance in major psychiatric disorders and summarize evidence that defective Wnt signaling could contribute to their pathogenesis via effects on these late neural differentiation processes.
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626
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Rapid induction and long-term self-renewal of primitive neural precursors from human embryonic stem cells by small molecule inhibitors. Proc Natl Acad Sci U S A 2011; 108:8299-304. [PMID: 21525408 DOI: 10.1073/pnas.1014041108] [Citation(s) in RCA: 285] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Human embryonic stem cells (hESCs) hold enormous promise for regenerative medicine. Typically, hESC-based applications would require their in vitro differentiation into a desirable homogenous cell population. A major challenge of the current hESC differentiation paradigm is the inability to effectively capture and, in the long-term, stably expand primitive lineage-specific stem/precursor cells that retain broad differentiation potential and, more importantly, developmental stage-specific differentiation propensity. Here, we report synergistic inhibition of glycogen synthase kinase 3 (GSK3), transforming growth factor β (TGF-β), and Notch signaling pathways by small molecules can efficiently convert monolayer cultured hESCs into homogenous primitive neuroepithelium within 1 wk under chemically defined condition. These primitive neuroepithelia can stably self-renew in the presence of leukemia inhibitory factor, GSK3 inhibitor (CHIR99021), and TGF-β receptor inhibitor (SB431542); retain high neurogenic potential and responsiveness to instructive neural patterning cues toward midbrain and hindbrain neuronal subtypes; and exhibit in vivo integration. Our work uniformly captures and maintains primitive neural stem cells from hESCs.
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627
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Licht-Murava A, Plotkin B, Eisenstein M, Eldar-Finkelman H. Elucidating Substrate and Inhibitor Binding Sites on the Surface of GSK-3β and the Refinement of a Competitive Inhibitor. J Mol Biol 2011; 408:366-78. [DOI: 10.1016/j.jmb.2011.02.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 02/07/2011] [Accepted: 02/16/2011] [Indexed: 12/25/2022]
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628
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Smillie KJ, Cousin MA. The Role of GSK3 in Presynaptic Function. Int J Alzheimers Dis 2011; 2011:263673. [PMID: 21547219 PMCID: PMC3087464 DOI: 10.4061/2011/263673] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 01/20/2011] [Indexed: 11/20/2022] Open
Abstract
The past ten years of research have identified a number of key roles for glycogen synthase kinase 3 (GSK3) at the synapse. In terms of presynaptic physiology, critical roles for GSK3 have been revealed in the growth and maturation of the nerve terminal and more recently a key role in the control of activity-dependent bulk endocytosis of synaptic vesicles. This paper will summarise the major roles assigned to GSK3 in both immature and mature nerve terminals, the substrates GSK3 phosphorylates to exert its action, and how GSK3 activity is regulated by different presynaptic signalling cascades. The number of essential roles for GSK3, coupled with the numerous signalling cascades all converging to regulate its activity, suggests that GSK3 is a key integrator of multiple inputs to modulate the strength of neurotransmission. Modulation of these pathways may point to potential mechanisms to overcome synaptic failure in neurodegenerative disorders such as Alzheimer's disease.
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Affiliation(s)
- Karen Janet Smillie
- Membrane Biology Group, Centre for Integrative Physiology, University of Edinburgh, George Square, EH8 9XD, Edinburgh, UK
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629
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Jinwal UK, Trotter JH, Abisambra JF, Koren J, Lawson LY, Vestal GD, O'Leary JC, Johnson AG, Jin Y, Jones JR, Li Q, Weeber EJ, Dickey CA. The Hsp90 kinase co-chaperone Cdc37 regulates tau stability and phosphorylation dynamics. J Biol Chem 2011; 286:16976-83. [PMID: 21367866 DOI: 10.1074/jbc.m110.182493] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The microtubule-associated protein tau, which becomes hyperphosphorylated and pathologically aggregates in a number of these diseases, is extremely sensitive to manipulations of chaperone signaling. For example, Hsp90 inhibitors can reduce the levels of tau in transgenic mouse models of tauopathy. Because of this, we hypothesized that a number of Hsp90 accessory proteins, termed co-chaperones, could also affect tau stability. Perhaps by identifying these co-chaperones, new therapeutics could be designed to specifically target these proteins and facilitate tau clearance. Here, we report that the co-chaperone Cdc37 can regulate aspects of tau pathogenesis. We found that suppression of Cdc37 destabilized tau, leading to its clearance, whereas Cdc37 overexpression preserved tau. Cdc37 was found to co-localize with tau in neuronal cells and to physically interact with tau from human brain. Moreover, Cdc37 levels significantly increased with age. Cdc37 knockdown altered the phosphorylation profile of tau, an effect that was due in part to reduced tau kinase stability, specifically Cdk5 and Akt. Conversely, GSK3β and Mark2 were unaffected by Cdc37 modulation. Cdc37 overexpression prevented whereas Cdc37 suppression potentiated tau clearance following Hsp90 inhibition. Thus, Cdc37 can regulate tau in two ways: by directly stabilizing it via Hsp90 and by regulating the stability of distinct tau kinases. We propose that changes in the neuronal levels or activity of Cdc37 could dramatically alter the kinome, leading to profound changes in the tau phosphorylation signature, altering its proteotoxicity and stability.
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Affiliation(s)
- Umesh K Jinwal
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, Florida 33613, USA
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630
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Mutant DISC1 affects methamphetamine-induced sensitization and conditioned place preference: a comorbidity model. Neuropharmacology 2011; 62:1242-51. [PMID: 21315744 DOI: 10.1016/j.neuropharm.2011.02.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Revised: 02/01/2011] [Accepted: 02/01/2011] [Indexed: 01/24/2023]
Abstract
Genetic factors involved in neuroplasticity have been implicated in major psychiatric illnesses such as schizophrenia, depression, and substance abuse. Given its extended interactome, variants in the Disrupted-In-Schizophrenia-1 (DISC1) gene could contribute to drug addiction and psychiatric diseases. Thus, we evaluated how dominant-negative mutant DISC1 influenced the neurobehavioral and molecular effects of methamphetamine (METH). Control and mutant DISC1 mice were studied before or after treatment with non-toxic escalating dose (ED) of METH. In naïve mice, we assessed METH-induced conditioned place preference (CPP), dopamine (DA) D2 receptor density and the basal and METH-induced activity of DISC1 partners, AKT and GSK-3β in the ventral striatum. In ED-treated mice, 4 weeks after METH treatment, we evaluated fear conditioning, depression-like responses in forced swim test, and the basal and METH-induced activity of AKT and GSK-3β in the ventral striatum. We found impairment in METH-induced CPP, decreased DA D2 receptor density and altered METH-induced phosphorylation of AKT and GSK-3β in naïve DISC1 female mice. The ED regimen was not neurotoxic as evidenced by unaltered brain regional monoamine tissue content. Mutant DISC1 significantly delayed METH ED-produced sensitization and affected drug-induced phosphorylation of AKT and GSK-3β in female mice. Our results suggest that perturbations in DISC1 functions in the ventral striatum may impact the molecular mechanisms of reward and sensitization, contributing to comorbidity between drug abuse and major mental diseases.
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631
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Campa VM, Kypta RM. Issues associated with the use of phosphospecific antibodies to localise active and inactive pools of GSK-3 in cells. Biol Direct 2011; 6:4. [PMID: 21261990 PMCID: PMC3039639 DOI: 10.1186/1745-6150-6-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 01/24/2011] [Indexed: 12/19/2022] Open
Abstract
Abstract Background Glycogen synthase kinase-3 (GSK-3) is a ubiquitously expressed serine/threonine (Ser/Thr) kinase comprising two isoforms, GSK-3α and GSK-3β. Both enzymes are similarly inactivated by serine phosphorylation (GSK-3α at Ser21 and GSK-3β at Ser9) and activated by tyrosine phosphorylation (GSK-3α at Tyr279 and GSK-3β at Tyr216). Antibodies raised to phosphopeptides containing the sequences around these phosphorylation sites are frequently used to provide an indication of the activation state of GSK-3 in cell and tissue extracts. These antibodies have further been used to determine the subcellular localisation of active and inactive forms of GSK-3, and the results of those studies support roles for GSK-3 phosphorylation in diverse cellular processes. However, the specificity of these antibodies in immunocytochemistry has not been addressed in any detail.
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Affiliation(s)
- Victor M Campa
- Cell Biology and Stem Cells Unit, Center for Cooperative Research in Biosciences (CIC bioGUNE), Bizkaia Technology Park, 48160 Derio, Spain
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632
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Shruster A, Eldar-Finkelman H, Melamed E, Offen D. Wnt signaling pathway overcomes the disruption of neuronal differentiation of neural progenitor cells induced by oligomeric amyloid β-peptide. J Neurochem 2011; 116:522-9. [PMID: 21138436 DOI: 10.1111/j.1471-4159.2010.07131.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neural stem cells give rise to new hippocampal neurons throughout adulthood. Defects in neurogenesis are associated with cognitive dysfunctions, such as Alzheimer disease (AD). Our understanding of the signals controlling this process is limited. The present in vitro study explored the manner in which the Wnt signaling pathway regulates the differentiation of hippocampal progenitors (HPs) into neurons under the influence of amyloid β(42) (Aβ(42) ). The results showed that oligomeric Aβ(42) reduced neuronal differentiation. This process was accompanied by a reduction in active β-catenin levels and proneural gene expression. The addition of Wnt3a increased the neuronal differentiation of Aβ(42) -treated HPs, at the expense of astrocyte differentiation. The effect of Wnt signaling was attributable to progenitor cell differentiation to the neuronal lineage, and not to increased proliferation or rescue of neurons. The interruption of Wnt signaling by oligomeric Aβ(42) may have clinical implications for the treatment of impaired neurogenesis in AD.
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Affiliation(s)
- Adi Shruster
- The Neuroscience Laboratory, Felsenstein Medical Research Center, Petach Tikva, Tel Aviv University, Tel Aviv, Israel
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633
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Abstract
Synapse formation is a critical step in the assembly of neuronal circuits. Both secreted and membrane-associated proteins contribute to the assembly and maturation of synapses. In addition, neuronal activity regulates the formation of neuronal circuits through the stimulation of growth factor secretion and the localization of receptors such as NMDA and AMPA receptors (NMDAR and AMPAR, respectively). Little is known, however, about the role of activity in the localization and function of receptors for synaptogenic molecules. Wnts are secreted proteins that play a role in synapse formation by regulating pre- and postsynaptic assembly at central and peripheral synapses. Wnts can signal through different receptors including Frizzleds (Fzs), the LRP5/6 coreceptors, Ror and Ryk. Fz receptors have been shown to mediate Wnt function during synapse formation. At the cell surface, Fz receptors are located at synaptic and extrasynaptic sites. Importantly, synaptic localization of Fzs is regulated by neuronal activity in a Wnt-dependent manner. In this review, we discuss the function of Wnt-Fz signaling in the assembly of central and peripheral synapses and the evidence supporting a role for Wnt ligands and their Fz receptors in activity-mediated synapse formation.
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Affiliation(s)
- Macarena Sahores
- Department of Cell and Developmental Biology, University College London, United Kingdom
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634
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O'Tuathaigh CMP, Desbonnet L, Moran PM, Waddington JL. Susceptibility genes for schizophrenia: mutant models, endophenotypes and psychobiology. Curr Top Behav Neurosci 2011; 12:209-50. [PMID: 22367925 DOI: 10.1007/7854_2011_194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Schizophrenia is characterised by a multifactorial aetiology that involves genetic liability interacting with epigenetic and environmental factors to increase risk for developing the disorder. A consensus view is that the genetic component involves several common risk alleles of small effect and/or rare but penetrant copy number variations. Furthermore, there is increasing evidence for broader, overlapping genetic-phenotypic relationships in psychosis; for example, the same susceptibility genes also confer risk for bipolar disorder. Phenotypic characterisation of genetic models of candidate risk genes and/or putative pathophysiological processes implicated in schizophrenia, as well as examination of epidemiologically relevant gene × environment interactions in these models, can illuminate molecular and pathobiological mechanisms involved in schizophrenia. The present chapter outlines both the evidence from phenotypic studies in mutant mouse models related to schizophrenia and recently described mutant models addressing such gene × environment interactions. Emphasis is placed on evaluating the extent to which mutant phenotypes recapitulate the totality of the disease phenotype or model selective endophenotypes. We also discuss new developments and trends in relation to the functional genomics of psychosis which might help to inform on the construct validity of mutant models of schizophrenia and highlight methodological challenges in phenotypic evaluation that relate to such models.
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Affiliation(s)
- Colm M P O'Tuathaigh
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin 2, Ireland,
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635
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Cheng S, Li L, He S, Liu J, Sun Y, He M, Grasing K, Premont RT, Suo WZ. GRK5 deficiency accelerates {beta}-amyloid accumulation in Tg2576 mice via impaired cholinergic activity. J Biol Chem 2010; 285:41541-8. [PMID: 21041302 PMCID: PMC3009881 DOI: 10.1074/jbc.m110.170894] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 10/24/2010] [Indexed: 12/25/2022] Open
Abstract
Membrane G protein-coupled receptor kinase 5 (GRK5) deficiency is linked to Alzheimer disease, yet its precise roles in the disease pathogenesis remain to be delineated. We have previously demonstrated that GRK5 deficiency selectively impairs desensitization of presynaptic M2 autoreceptors, which causes presynaptic M2 hyperactivity and inhibits acetylcholine release. Here we report that inactivation of one copy of Grk5 gene in transgenic mice overexpressing β-amyloid precursor protein (APP) carrying Swedish mutations (Tg2576 or APPsw) resulted in significantly increased β-amyloid (Aβ) accumulation, including increased Aβ(+) plaque burdens and soluble Aβ in brain lysates and interstitial fluid (ISF). In addition, secreted β-APP fragment (sAPPβ) also increased, whereas full-length APP level did not change, suggesting an alteration in favor of β-amyloidogenic APP processing in these animals. Reversely, perfusion of methoctramine, a selective M2 antagonist, fully corrected the difference between the control and GRK5-deficient APPsw mice for ISF Aβ. In contrast, a cholinesterase inhibitor, eserine, although significantly decreasing the ISF Aβ in both control and GRK5-deficient APPsw mice, failed to correct the difference between them. However, combining eserine with methoctramine additively reduced the ISF Aβ further in both animals. Altogether, these findings indicate that GRK5 deficiency accelerates β-amyloidogenic APP processing and Aβ accumulation in APPsw mice via impaired cholinergic activity and that presynaptic M2 hyperactivity is the specific target for eliminating the pathologic impact of GRK5 deficiency. Moreover, a combination of an M2 antagonist and a cholinesterase inhibitor may reach the maximal disease-modifying effect for both amyloid pathology and cholinergic dysfunction.
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Affiliation(s)
- Shaowu Cheng
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Longxuan Li
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Department of Neurology, Guangdong Medical College Affiliated Hospital, Zhanjiang 524001, China
| | - Shuangteng He
- the Substance Abuse Research Laboratory, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Jun Liu
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Department of Neurology, the Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510120, China
| | - Yuning Sun
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Minchao He
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- The Department of Biochemistry and Molecular Biology, Ningxia Medical University, Yinchuan, Ningxia 750004, China, and
| | - Kenneth Grasing
- the Substance Abuse Research Laboratory, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Richard T. Premont
- the Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710
| | - William Z. Suo
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Departments of Neurology and
- Physiology, University of Kansas Medical College, Kansas City, Kansas 66170
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636
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Abazyan B, Nomura J, Kannan G, Ishizuka K, Tamashiro KLK, Nucifora F, Pogorelov V, Ladenheim B, Yang C, Krasnova IN, Cadet JL, Pardo C, Mori S, Kamiya A, Vogel M, Sawa A, Ross CA, Pletnikov MV. Prenatal interaction of mutant DISC1 and immune activation produces adult psychopathology. Biol Psychiatry 2010; 68:1172-81. [PMID: 21130225 PMCID: PMC3026608 DOI: 10.1016/j.biopsych.2010.09.022] [Citation(s) in RCA: 203] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 09/02/2010] [Accepted: 09/06/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND Gene-environment interactions (GEI) are involved in the pathogenesis of mental diseases. We evaluated interaction between mutant human disrupted-in-schizophrenia 1 (mhDISC1) and maternal immune activation implicated in schizophrenia and mood disorders. METHODS Pregnant mice were treated with saline or polyinosinic:polycytidylic acid at gestation day 9. Levels of inflammatory cytokines were measured in fetal and adult brains; expression of mhDISC1, endogenous DISC1, lissencephaly type 1, nuclear distribution protein nudE-like 1, glycoprotein 130, growth factor receptor-bound protein 2, and glycogen synthase kinase-3beta were assessed in cortical samples of newborn mice. Tissue content of monoamines, volumetric brain abnormalities, dendritic spine density in the hippocampus, and various domains of the mouse behavior repertoire were evaluated in adult male mice. RESULTS Prenatal interaction produced anxiety, depression-like responses, and altered social behavior that were accompanied by decreased reactivity of the hypothalamic-pituitary-adrenal axis, attenuated serotonin neurotransmission in the hippocampus, reduced enlargement of lateral ventricles, decreased volumes of amygdala and periaqueductal gray matter and density of spines on dendrites of granule cells of the hippocampus. Prenatal interaction modulated secretion of inflammatory cytokines in fetal brains, levels of mhDISC1, endogenous mouse DISC1, and glycogen synthase kinase-3beta. The behavioral effects of GEI were observed only if mhDISC1 was expressed throughout the life span. CONCLUSIONS Prenatal immune activation interacted with mhDISC1 to produce the neurobehavioral phenotypes that were not seen in untreated mhDISC1 mice and that resemble aspects of major mental illnesses. Our DISC1 mouse model is a valuable system to study GEI relevant to mental illnesses.
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Affiliation(s)
- B. Abazyan
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - J. Nomura
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - G. Kannan
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - K. Ishizuka
- Program in Molecular Psychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - K. L. K. Tamashiro
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - F. Nucifora
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - V. Pogorelov
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - B. Ladenheim
- Molecular Neuropsychiatry Branch, NIDA, NIH, DHHS, Baltimore, MD
| | - C. Yang
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - I. N. Krasnova
- Molecular Neuropsychiatry Branch, NIDA, NIH, DHHS, Baltimore, MD
| | - J. L. Cadet
- Molecular Neuropsychiatry Branch, NIDA, NIH, DHHS, Baltimore, MD
| | - C. Pardo
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - S. Mori
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - A. Kamiya
- Program in Molecular Psychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - M. Vogel
- Maryland Psychiatric Research Center, University of Maryland, Baltimore, MD
| | - A. Sawa
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, Program in Molecular Psychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, The McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - C. A. Ross
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD, Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - M. V. Pletnikov
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD, Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD,The corresponding author: Mikhail V. Pletnikov, MD; PhD, Johns Hopkins University School of Medicine, 600 North Wolfe Street; CMSC 8-121, Baltimore, MD 21287, USA, Phone: 410-502-3760, FAX: 410-614-0013,
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637
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Yokota Y, Eom TY, Stanco A, Kim WY, Rao S, Snider WD, Anton ES. Cdc42 and Gsk3 modulate the dynamics of radial glial growth, inter-radial glial interactions and polarity in the developing cerebral cortex. Development 2010; 137:4101-10. [PMID: 21062867 DOI: 10.1242/dev.048637] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Polarized radial glia are crucial to the formation of the cerebral cortex. They serve as neural progenitors and as guides for neuronal placement in the developing cerebral cortex. The maintenance of polarized morphology is essential for radial glial functions, but the extent to which the polarized radial glial scaffold is static or dynamic during corticogenesis remains an open question. The developmental dynamics of radial glial morphology, inter-radial glial interactions during corticogenesis, and the role of the cell polarity complexes in these activities remain undefined. Here, using real-time imaging of cohorts of mouse radial glia cells, we show that the radial glial scaffold, upon which the cortex is constructed, is highly dynamic. Radial glial cells within the scaffold constantly interact with one another. These interactions are mediated by growth cone-like endfeet and filopodia-like protrusions. Polarized expression of the cell polarity regulator Cdc42 in radial glia regulates glial endfeet activities and inter-radial glial interactions. Furthermore, appropriate regulation of Gsk3 activity is required to maintain the overall polarity of the radial glia scaffold. These findings reveal dynamism and interactions among radial glia that appear to be crucial contributors to the formation of the cerebral cortex. Related cell polarity determinants (Cdc42, Gsk3) differentially influence radial glial activities within the evolving radial glia scaffold to coordinate the formation of cerebral cortex.
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Affiliation(s)
- Yukako Yokota
- UNC Neuroscience Center and the Department of Cell and Molecular Physiology, The University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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638
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Voskas D, Ling LS, Woodgett JR. Does GSK-3 provide a shortcut for PI3K activation of Wnt signalling? F1000 BIOLOGY REPORTS 2010; 2:82. [PMID: 21283602 PMCID: PMC3026644 DOI: 10.3410/b2-82] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Glycogen synthase kinase-3 (GSK-3) is a well-established downstream component of the phosphatidylinositol 3-kinase (PI3K) signalling pathway but is also a key enzyme in negatively regulating the canonical Wnt/β-catenin signalling pathway. Several recent studies argue that PKB (protein kinase B)-mediated inhibition of GSK-3 leads to β-catenin accumulation, but whether cross-talk actually exists between these two pathways is controversial. To elucidate the mechanisms of shared signalling components, further studies taking into account different components of the PI3K signalling pathway and different pools of GSK-3 or β-catenin are required.
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Affiliation(s)
- Daniel Voskas
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University AvenueToronto, ON, M5G 1X5Canada
| | - Ling S Ling
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University AvenueToronto, ON, M5G 1X5Canada
| | - James R Woodgett
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University AvenueToronto, ON, M5G 1X5Canada
- Department of Medical Biophysics, University of Toronto, 27 King's College CircleToronto, ON, M5S 1A1Canada
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