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Mackiewicz J, Lisek M, Boczek T. Targeting CaN/NFAT in Alzheimer's brain degeneration. Front Immunol 2023; 14:1281882. [PMID: 38077352 PMCID: PMC10701682 DOI: 10.3389/fimmu.2023.1281882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/06/2023] [Indexed: 12/18/2023] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive loss of cognitive functions. While the exact causes of this debilitating disorder remain elusive, numerous investigations have characterized its two core pathologies: the presence of β-amyloid plaques and tau tangles. Additionally, multiple studies of postmortem brain tissue, as well as results from AD preclinical models, have consistently demonstrated the presence of a sustained inflammatory response. As the persistent immune response is associated with neurodegeneration, it became clear that it may also exacerbate other AD pathologies, providing a link between the initial deposition of β-amyloid plaques and the later development of neurofibrillary tangles. Initially discovered in T cells, the nuclear factor of activated T-cells (NFAT) is one of the main transcription factors driving the expression of inflammatory genes and thus regulating immune responses. NFAT-dependent production of inflammatory mediators is controlled by Ca2+-dependent protein phosphatase calcineurin (CaN), which dephosphorylates NFAT and promotes its transcriptional activity. A substantial body of evidence has demonstrated that aberrant CaN/NFAT signaling is linked to several pathologies observed in AD, including neuronal apoptosis, synaptic deficits, and glia activation. In view of this, the role of NFAT isoforms in AD has been linked to disease progression at different stages, some of which are paralleled to diminished cognitive status. The use of classical inhibitors of CaN/NFAT signaling, such as tacrolimus or cyclosporine, or adeno-associated viruses to specifically inhibit astrocytic NFAT activation, has alleviated some symptoms of AD by diminishing β-amyloid neurotoxicity and neuroinflammation. In this article, we discuss the recent findings related to the contribution of CaN/NFAT signaling to the progression of AD and highlight the possible benefits of targeting this pathway in AD treatment.
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Affiliation(s)
| | | | - Tomasz Boczek
- Department of Molecular Neurochemistry, Medical University of Lodz, Lodz, Poland
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2
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Wong H, Buck JM, Borski C, Pafford JT, Keller BN, Milstead RA, Hanson JL, Stitzel JA, Hoeffer CA. RCAN1 knockout and overexpression recapitulate an ensemble of rest-activity and circadian disruptions characteristic of Down syndrome, Alzheimer's disease, and normative aging. J Neurodev Disord 2022; 14:33. [PMID: 35610565 PMCID: PMC9128232 DOI: 10.1186/s11689-022-09444-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 05/12/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Regulator of calcineurin 1 (RCAN1) is overexpressed in Down syndrome (DS), but RCAN1 levels are also increased in Alzheimer's disease (AD) and normal aging. AD is highly comorbid among individuals with DS and is characterized in part by progressive neurodegeneration that resembles accelerated aging. Importantly, abnormal RCAN1 levels have been demonstrated to promote memory deficits and pathophysiology that appear symptomatic of DS, AD, and aging. Anomalous diurnal rest-activity patterns and circadian rhythm disruptions are also common in DS, AD, and aging and have been implicated in facilitating age-related cognitive decline and AD progression. However, no prior studies have assessed whether RCAN1 dysregulation may also promote the age-associated alteration of rest-activity profiles and circadian rhythms, which could in turn contribute to neurodegeneration in DS, AD, and aging. METHODS The present study examined the impacts of RCAN1 deficiency and overexpression on the photic entrainment, circadian periodicity, intensity and distribution, diurnal patterning, and circadian rhythmicity of wheel running in young (3-6 months old) and aged (9-14 months old) mice of both sexes. RESULTS We found that daily RCAN1 levels in the hippocampus and suprachiasmatic nucleus (SCN) of light-entrained young mice are generally constant and that balanced RCAN1 expression is necessary for normal circadian locomotor activity rhythms. While the light-entrained diurnal period was unaltered, RCAN1-null and RCAN1-overexpressing mice displayed lengthened endogenous (free-running) circadian periods like mouse models of AD and aging. In light-entrained young mice, RCAN1 deficiency and overexpression also recapitulated the general hypoactivity, diurnal rest-wake pattern fragmentation, and attenuated amplitudes of circadian activity rhythms reported in DS, preclinical and clinical AD, healthily aging individuals, and rodent models thereof. Under constant darkness, RCAN1-null and RCAN1-overexpressing mice displayed altered locomotor behavior indicating circadian clock dysfunction. Using the Dp(16)1Yey/+ (Dp16) mouse model for DS, which expresses three copies of Rcan1, we found reduced wheel running activity and rhythmicity in both light-entrained and free-running young Dp16 mice like young RCAN1-overexpressing mice. Critically, these diurnal and circadian deficits were rescued in part or entirely by restoring Rcan1 to two copies in Dp16 mice. We also found that RCAN1 deficiency but not RCAN1 overexpression altered protein levels of the clock gene Bmal1 in the SCN. CONCLUSIONS Collectively, this study's findings suggest that both loss and aberrant gain of RCAN1 precipitate anomalous light-entrained diurnal and circadian activity patterns emblematic of DS, AD, and possibly aging.
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Affiliation(s)
- Helen Wong
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA
| | - Jordan M Buck
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA
| | - Curtis Borski
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA
| | - Jessica T Pafford
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA
| | - Bailey N Keller
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA
| | - Ryan A Milstead
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA
| | - Jessica L Hanson
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA
| | - Jerry A Stitzel
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA
| | - Charles A Hoeffer
- Institute for Behavioral Genetics, University of Colorado Boulder, 1480 30th Street, Boulder, CO, 80309-0447, USA.
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80303, USA.
- Linda Crnic Institute, Anschutz Medical Campus, Aurora, CO, 80045, USA.
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3
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Ishihara K. The accumulation of copper in the brain of Down syndrome promotes oxidative stress: possible mechanism underlying cognitive impairment. J Clin Biochem Nutr 2022; 71:16-21. [PMID: 35903608 PMCID: PMC9309086 DOI: 10.3164/jcbn.21-155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 12/29/2021] [Indexed: 11/22/2022] Open
Affiliation(s)
- Keiichi Ishihara
- Department of Pathological Biochemistry, Kyoto Pharmaceutical University
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4
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Kim SS, Lee EH, Shin JH, Seo SR. MAP kinase/ERK kinase 1 (MEK1) phosphorylates regulator of calcineurin 1 (RCAN1) to regulate neuronal differentiation. J Cell Physiol 2021; 237:1406-1417. [PMID: 34647615 DOI: 10.1002/jcp.30609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 09/27/2021] [Accepted: 10/04/2021] [Indexed: 11/08/2022]
Abstract
Regulator of calcineurin 1 (RCAN1) is located close to the Down syndrome critical region (DSCR) on human chromosome 21 and is related to the Down syndrome (DS) phenotype. To identify a novel binding partner of RCAN1, we performed yeast two-hybrid screening and identified mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase (ERK) kinase 1 (MEK1) as a partner. MEK1 was able to bind and phosphorylate RCAN1 in vitro and in vivo. MEK1-dependent RCAN1 phosphorylation caused an increase in RCAN1 expression by increasing the protein half-life. Nerve growth factor (NGF)-dependent activation of the MEK1 pathway consistently induced RCAN1 expression. Moreover, we found that RCAN1 overexpression inhibited NGF-induced neurite outgrowth and expression of neuronal marker genes, such as growth cone-associated protein 43 (GAP43) and synapsin I, via inhibition of MEK1-ERK1/2 pathways. Our findings provide evidence that MEK1-dependent RCAN1 phosphorylation acts as an important molecular mechanism in the control of neuronal differentiation.
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Affiliation(s)
- Seon Sook Kim
- Department of Molecular Bioscience, Kangwon National University, Chuncheon, Republic of Korea
| | - Eun Hye Lee
- Department of Molecular Bioscience, Kangwon National University, Chuncheon, Republic of Korea
| | - Jin Hak Shin
- Department of Molecular Bioscience, Kangwon National University, Chuncheon, Republic of Korea
| | - Su Ryeon Seo
- Department of Molecular Bioscience, Kangwon National University, Chuncheon, Republic of Korea
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5
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Roper RJ, Goodlett CR, Martínez de Lagrán M, Dierssen M. Behavioral Phenotyping for Down Syndrome in Mice. ACTA ACUST UNITED AC 2020; 10:e79. [PMID: 32780566 DOI: 10.1002/cpmo.79] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Down syndrome (DS) is the most frequent genetic cause of intellectual disability, characterized by alterations in different behavioral symptom domains: neurodevelopment, motor behavior, and cognition. As mouse models have the potential to generate data regarding the neurological basis for the specific behavioral profile of DS, and may indicate pharmacological treatments with the potential to affect their behavioral phenotype, it is important to be able to assess disease-relevant behavioral traits in animal models in order to provide biological plausibility to the potential findings. The field is at a juncture that requires assessments that may effectively translate the findings acquired in mouse models to humans with DS. In this article, behavioral tests are described that are relevant to the domains affected in DS. A neurodevelopmental behavioral screen, the balance beam test, and the Multivariate Concentric Square Field test to assess multiple behavioral phenotypes and locomotion are described, discussing the ways to merge these findings to more fully understand cognitive strengths and weaknesses in this population. New directions for approaches to cognitive assessment in mice and humans are discussed. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Preweaning neurodevelopmental battery Basic Protocol 2: Balance beam Basic Protocol 3: Multivariate concentric square field test (MCSF).
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Affiliation(s)
| | | | - María Martínez de Lagrán
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Mara Dierssen
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain.,Biomedical Research Networking Center on Rare Diseases (CIBERER), Institute of Health Carlos III, Madrid, Spain
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6
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Dierssen M, Fructuoso M, Martínez de Lagrán M, Perluigi M, Barone E. Down Syndrome Is a Metabolic Disease: Altered Insulin Signaling Mediates Peripheral and Brain Dysfunctions. Front Neurosci 2020; 14:670. [PMID: 32733190 PMCID: PMC7360727 DOI: 10.3389/fnins.2020.00670] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/02/2020] [Indexed: 12/19/2022] Open
Abstract
Down syndrome (DS) is the most frequent chromosomal abnormality that causes intellectual disability, resulting from the presence of an extra complete or segment of chromosome 21 (HSA21). In addition, trisomy of HSA21 contributes to altered energy metabolism that appears to be a strong determinant in the development of pathological phenotypes associated with DS. Alterations include, among others, mitochondrial defects, increased oxidative stress levels, impaired glucose, and lipid metabolism, finally resulting in reduced energy production and cellular dysfunctions. These molecular defects seem to account for a high incidence of metabolic disorders, i.e., diabetes and/or obesity, as well as a higher risk of developing Alzheimer’s disease (AD) in DS. A dysregulation of the insulin signaling with reduced downstream pathways represents a common pathophysiological aspect in the development of both peripheral and central alterations leading to diabetes/obesity and AD. This is further strengthened by evidence showing that the molecular mechanisms responsible for such alterations appear to be similar between peripheral organs and brain. Considering that DS subjects are at high risk to develop either peripheral or brain metabolic defects, this review will discuss current knowledge about the link between trisomy of HSA21 and defects of insulin and insulin-related pathways in DS. Drawing the molecular signature underlying these processes in DS is a key challenge to identify novel drug targets and set up new prevention strategies aimed to reduce the impact of metabolic disorders and cognitive decline.
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Affiliation(s)
- Mara Dierssen
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain.,Human Pharmacology and Clinical Neurosciences Research Group, Neurosciences Research Program, Hospital Del Mar Medical Research Institute (IMIM), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Marta Fructuoso
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain
| | - María Martínez de Lagrán
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Marzia Perluigi
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, Rome, Italy
| | - Eugenio Barone
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, Rome, Italy
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7
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RCAN1 Inhibits BACE2 Turnover by Attenuating Proteasome-Mediated BACE2 Degradation. BIOMED RESEARCH INTERNATIONAL 2020; 2020:1920789. [PMID: 32566665 PMCID: PMC7293731 DOI: 10.1155/2020/1920789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 05/22/2020] [Indexed: 11/23/2022]
Abstract
Amyloid-β protein (Aβ) is the main component of neuritic plaques, the pathological hallmark of Alzheimer's disease (AD). β-site APP cleaving enzyme 1 (BACE1) is a major β-secretase contributing to Aβ generation. β-site APP cleaving enzyme 2 (BACE2), the homolog of BACE1, is not only a θ-secretase but also a conditional β-secretase. Previous studies showed that regulator of calcineurin 1 (RCAN1) is markedly increased by AD and promotes BACE1 expression. However, the role of RCAN1 in BACE2 regulation remains elusive. Here, we showed that RCAN1 increases BACE2 protein levels. Moreover, RCAN1 inhibits the turnover of BACE2 protein. Furthermore, RCAN1 attenuates proteasome-mediated BACE2 degradation, but not lysosome-mediated BACE2 degradation. Taken together, our work indicates that RCAN1 inhibits BACE2 turnover by attenuating proteasome-mediated BACE2 degradation. It advances our understanding of BACE2 regulation and provides a potential mechanism of BACE2 dysregulation in AD.
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8
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Thimet Oligopeptidase (EC 3.4.24.15) Key Functions Suggested by Knockout Mice Phenotype Characterization. Biomolecules 2019; 9:biom9080382. [PMID: 31431000 PMCID: PMC6722639 DOI: 10.3390/biom9080382] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/29/2019] [Accepted: 07/29/2019] [Indexed: 12/14/2022] Open
Abstract
Thimet oligopeptidase (THOP1) is thought to be involved in neuropeptide metabolism, antigen presentation, neurodegeneration, and cancer. Herein, the generation of THOP1 C57BL/6 knockout mice (THOP1−/−) is described showing that they are viable, have estrus cycle, fertility, and a number of puppies per litter similar to C57BL/6 wild type mice (WT). In specific brain regions, THOP1-/- exhibit altered mRNA expression of proteasome beta5, serotonin 5HT2a receptor and dopamine D2 receptor, but not of neurolysin (NLN). Peptidomic analysis identifies differences in intracellular peptide ratios between THOP1-/- and WT mice, which may affect normal cellular functioning. In an experimental model of multiple sclerosis THOP1-/- mice present worse clinical behavior scores compared to WT mice, corroborating its possible involvement in neurodegenerative diseases. THOP1-/- mice also exhibit better survival and improved behavior in a sepsis model, but also a greater peripheral pain sensitivity measured in the hot plate test after bradykinin administration in the paw. THOP1-/- mice show depressive-like behavior, as well as attention and memory retention deficits. Altogether, these results reveal a role of THOP1 on specific behaviors, immune-stimulated neurodegeneration, and infection-induced inflammation.
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9
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Choi C, Kim T, Chang KT, Min K. DSCR1-mediated TET1 splicing regulates miR-124 expression to control adult hippocampal neurogenesis. EMBO J 2019; 38:e101293. [PMID: 31304631 PMCID: PMC6627232 DOI: 10.15252/embj.2018101293] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 11/09/2022] Open
Abstract
Whether epigenetic factors such as DNA methylation and microRNAs interact to control adult hippocampal neurogenesis is not fully understood. Here, we show that Down syndrome critical region 1 (DSCR1) protein plays a key role in adult hippocampal neurogenesis by modulating two epigenetic factors: TET1 and miR-124. We find that DSCR1 mutant mice have impaired adult hippocampal neurogenesis. DSCR1 binds to TET1 introns to regulate splicing of TET1, thereby modulating TET1 level. Furthermore, TET1 controls the demethylation of the miRNA-124 promoter to modulate miR-124 expression. Correcting the level of TET1 in DSCR1 knockout mice is sufficient to prevent defective adult neurogenesis. Importantly, restoring DSCR1 level in a Down syndrome mouse model effectively rescued adult neurogenesis and learning and memory deficits. Our study reveals that DSCR1 plays a critical upstream role in epigenetic regulation of adult neurogenesis and provides insights into potential therapeutic strategy for treating cognitive defects in Down syndrome.
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Affiliation(s)
- Chiyeol Choi
- Department of Biological SciencesSchool of Life SciencesUlsan National Institute of Science and TechnologyUlsanKorea
- National Creative Research Initiative Center for ProteostasisUlsan National Institute of Science and TechnologyUlsanKorea
| | - Taehoon Kim
- Department of Biological SciencesSchool of Life SciencesUlsan National Institute of Science and TechnologyUlsanKorea
- National Creative Research Initiative Center for ProteostasisUlsan National Institute of Science and TechnologyUlsanKorea
| | - Karen T Chang
- Zilkha Neurogenetic InstituteKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Kyung‐Tai Min
- Department of Biological SciencesSchool of Life SciencesUlsan National Institute of Science and TechnologyUlsanKorea
- National Creative Research Initiative Center for ProteostasisUlsan National Institute of Science and TechnologyUlsanKorea
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10
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Vásquez-Navarrete J, Martínez AD, Ory S, Baéz-Matus X, González-Jamett AM, Brauchi S, Caviedes P, Cárdenas AM. RCAN1 Knockdown Reverts Defects in the Number of Calcium-Induced Exocytotic Events in a Cellular Model of Down Syndrome. Front Cell Neurosci 2018; 12:189. [PMID: 30034324 PMCID: PMC6043644 DOI: 10.3389/fncel.2018.00189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 06/12/2018] [Indexed: 12/15/2022] Open
Abstract
In humans, Down Syndrome (DS) is a condition caused by partial or full trisomy of chromosome 21. Genes present in the DS critical region can result in excess gene dosage, which at least partially can account for DS phenotype. Although regulator of calcineurin 1 (RCAN1) belongs to this region and its ectopic overexpression in neurons impairs transmitter release, synaptic plasticity, learning and memory, the relative contribution of RCAN1 in a context of DS has yet to be clarified. In the present work, we utilized an in vitro model of DS, the CTb neuronal cell line derived from the brain cortex of a trisomy 16 (Ts16) fetal mouse, which reportedly exhibits acetylcholine release impairments compared to CNh cells (a neuronal cell line established from a normal littermate). We analyzed single exocytotic events by using total internal reflection fluorescence microscopy (TIRFM) and the vesicular acetylcholine transporter fused to the pH-sensitive green fluorescent protein (VAChT-pHluorin) as a reporter. Our analyses showed that, compared with control CNh cells, the trisomic CTb cells overexpress RCAN1, and they display a reduced number of Ca2+-induced exocytotic events. Remarkably, RCAN1 knockdown increases the extent of exocytosis at levels comparable to those of CNh cells. These results support a critical contribution of RCAN1 to the exocytosis process in the trisomic condition.
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Affiliation(s)
- Jacqueline Vásquez-Navarrete
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Agustín D Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Stéphane Ory
- Centre National de la Recherche Scientifique (CNRS UPR 3212), Institut des Neurosciences Cellulaires et Intégratives (INCI), Strasbourg, France
| | - Ximena Baéz-Matus
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Arlek M González-Jamett
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Sebastián Brauchi
- Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Pablo Caviedes
- Programa de Farmacología Molecular y Clínica, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Centro de Biotecnología y Bioingeniería (CeBiB), Departamento de Ingeniería Química, Biotecnología y Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
| | - Ana M Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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11
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Kleschevnikov AM, Yu J, Kim J, Lysenko LV, Zeng Z, Yu YE, Mobley WC. Evidence that increased Kcnj6 gene dose is necessary for deficits in behavior and dentate gyrus synaptic plasticity in the Ts65Dn mouse model of Down syndrome. Neurobiol Dis 2017; 103:1-10. [PMID: 28342823 DOI: 10.1016/j.nbd.2017.03.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 02/09/2017] [Accepted: 03/21/2017] [Indexed: 11/15/2022] Open
Abstract
Down syndrome (DS), trisomy 21, is caused by increased dose of genes present on human chromosome 21 (HSA21). The gene-dose hypothesis argues that a change in the dose of individual genes or regulatory sequences on HSA21 is necessary for creating DS-related phenotypes, including cognitive impairment. We focused on a possible role for Kcnj6, the gene encoding Kir3.2 (Girk2) subunits of a G-protein-coupled inwardly-rectifying potassium channel. This gene resides on a segment of mouse Chromosome 16 that is present in one extra copy in the genome of the Ts65Dn mouse, a well-studied genetic model of DS. Kir3.2 subunit-containing potassium channels serve as effectors for a number of postsynaptic metabotropic receptors including GABAB receptors. Several studies raise the possibility that increased Kcnj6 dose contributes to synaptic and cognitive abnormalities in DS. To assess directly a role for Kcnj6 gene dose in cognitive deficits in DS, we produced Ts65Dn mice that harbor only 2 copies of Kcnj6 (Ts65Dn:Kcnj6++- mice). The reduction in Kcnj6 gene dose restored to normal the hippocampal level of Kir3.2. Long-term memory, examined in the novel object recognition test with the retention period of 24h, was improved to the level observed in the normosomic littermate control mice (2N:Kcnj6++). Significantly, both short-term and long-term potentiation (STP and LTP) was improved to control levels in the dentate gyrus (DG) of the Ts65Dn:Kcnj6++- mouse. In view of the ability of fluoxetine to suppress Kir3.2 channels, we asked if fluoxetine-treated DG slices of Ts65Dn:Kcnj6+++ mice would rescue synaptic plasticity. Fluoxetine increased STP and LTP to control levels. These results are evidence that increased Kcnj6 gene dose is necessary for synaptic and cognitive dysfunction in the Ts65Dn mouse model of DS. Strategies aimed at pharmacologically reducing channel function should be explored for enhancing cognition in DS.
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Affiliation(s)
- Alexander M Kleschevnikov
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
| | - Jessica Yu
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Jeesun Kim
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Larisa V Lysenko
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Academy of Biology and Biotechnology of Southern Federal University, 194/1 Stachki Str, Rostov-na-Donu 344090, Russian Federation
| | - Zheng Zeng
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Y Eugene Yu
- The Children's Guild Foundation Down Syndrome Research Program, Genetics Program and Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
| | - William C Mobley
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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12
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Li W, Choi TW, Ahnn J, Lee SK. Allele-Specific Phenotype Suggests a Possible Stimulatory Activity of RCAN-1 on Calcineurin in Caenorhabditis elegans. Mol Cells 2016; 39:827-833. [PMID: 27871170 PMCID: PMC5125939 DOI: 10.14348/molcells.2016.0222] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 10/27/2016] [Accepted: 10/31/2016] [Indexed: 11/27/2022] Open
Abstract
Regulator of calcineurin 1 (RCAN1) binds to calcineurin through the PxIxIT motif, which is evolutionarily conserved. SP repeat phosphorylation in RCAN1 is required for its complete function. The specific interaction between RCAN1 and calcineurin is critical for calcium/calmodulin-dependent regulation of calcineurin serine/threonine phosphatase activity. In this study, we investigated two available deletion rcan-1 mutants in Caenorhabditis elegans, which proceed differently for transcription and translation. We found that rcan-1 may be required for calcineurin activity and possess calcineurin-independent function in body growth and egg-laying behavior. In the genetic background of enhanced calcineurin activity, the rcan-1 mutant expressing a truncated RCAN-1 which retains the calcineurin-binding PxIxIT motif but misses SP repeats stimulated growth, while rcan-1 lack mutant resulted in hyperactive egg-laying suppression. These data suggest rcan-1 has unknown functions independent of calcineurin, and may be a stimulatory calcineurin regulator under certain circumstances.
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Affiliation(s)
- Weixun Li
- Department of Life Science, Hanyang University, Seoul 04763,
Korea
- BK21 PLUS Life Science for BDR Team, Hanyang University, Seoul 04763,
Korea
- Research Institute for Natural Sciences, Hanyang University, Seoul 04763,
Korea
| | - Tae-Woo Choi
- Department of Life Science, Hanyang University, Seoul 04763,
Korea
- BK21 PLUS Life Science for BDR Team, Hanyang University, Seoul 04763,
Korea
- Research Institute for Natural Sciences, Hanyang University, Seoul 04763,
Korea
| | - Joohong Ahnn
- Department of Life Science, Hanyang University, Seoul 04763,
Korea
- BK21 PLUS Life Science for BDR Team, Hanyang University, Seoul 04763,
Korea
- Research Institute for Natural Sciences, Hanyang University, Seoul 04763,
Korea
| | - Sun-Kyung Lee
- Department of Life Science, Hanyang University, Seoul 04763,
Korea
- BK21 PLUS Life Science for BDR Team, Hanyang University, Seoul 04763,
Korea
- Research Institute for Natural Sciences, Hanyang University, Seoul 04763,
Korea
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13
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Li B, He X, Sun Y, Li B. Developmental exposure to paraquat and maneb can impair cognition, learning and memory in Sprague-Dawley rats. MOLECULAR BIOSYSTEMS 2016; 12:3088-97. [PMID: 27460631 DOI: 10.1039/c6mb00284f] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Paraquat and maneb are identified environmental pollutants. Combined exposure to paraquat and maneb is a latent risk factor for many diseases, particularly those of the central nervous system, including Parkinson's disease and Alzheimer's disease. Hippocampus is the key structure in memory formation and babies are more sensitive to environmental stimuli than adults, so we investigated the neurotoxicity of paraquat and maneb on the hippocampi of rat pups. Female and male Sprague-Dawley rats were mated (female : male = 2 : 1) every night for a week. The gravid rats were randomly divided into three groups (one control and two experimental groups). A mixed solution of paraquat-maneb was administered twice a week by lavage at a dose of 10 or 15 mg kg(-1) bodyweight (containing 30 or 45 mg kg(-1) bodyweight maneb, respectively) from day 6 after pregnancy till ablactation. Maternal weight gain and offspring bodyweights were not affected by the drugs. However, behavioral tests showed that reaction latency and mistake frequency increased after treatment. Intuitively, we found significant changes in the hippocampal neurons in the morphological observation. Taking into account the interaction of the related genes in the cAMP-PKA-CREB pathway, we used a variety of methods to detect the gene and protein levels. Reduced expression of cAMP and related genes and proteins in the hippocampus and serum was also observed. These results indicate that PQ-MB stimulates cAMP to reduce the production of PKA, thus reducing the phosphorylation of CREB and inhibiting the activation of other elements (BDNF, C-JUN, and C-FOS). These changes lead to hippocampal damage and impaired abilities (learning, cognition, and memory). Our results demonstrate that PQ-MB induces hippocampal toxicity in the early life of rats, and they thus provide a theoretical foundation for further investigation of the bathypelagic mechanism involved and measures that can be taken to avoid PQ-MB neurotoxicity.
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Affiliation(s)
- Bai Li
- Department of Toxicology, College of Public Health, Harbin Medical University, Harbin, Heilongjiang Province 150081, P. R. China.
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14
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Wang W, Rai A, Hur EM, Smilansky Z, Chang KT, Min KT. DSCR1 is required for both axonal growth cone extension and steering. J Cell Biol 2016; 213:451-62. [PMID: 27185837 PMCID: PMC4878092 DOI: 10.1083/jcb.201510107] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/22/2016] [Indexed: 11/26/2022] Open
Abstract
Wang et al. identify that DSCR1, a gene on chromosome 21 that is associated with Down syndrome, controls both the rate and direction of axon growth in response to extrinsic cues by regulating cytoskeletal dynamics and local protein synthesis in the growth cone. Local information processing in the growth cone is essential for correct wiring of the nervous system. As an axon navigates through the developing nervous system, the growth cone responds to extrinsic guidance cues by coordinating axon outgrowth with growth cone steering. It has become increasingly clear that axon extension requires proper actin polymerization dynamics, whereas growth cone steering involves local protein synthesis. However, molecular components integrating these two processes have not been identified. Here, we show that Down syndrome critical region 1 protein (DSCR1) controls axon outgrowth by modulating growth cone actin dynamics through regulation of cofilin activity (phospho/dephospho-cofilin). Additionally, DSCR1 mediates brain-derived neurotrophic factor–induced local protein synthesis and growth cone turning. Our study identifies DSCR1 as a key protein that couples axon growth and pathfinding by dually regulating actin dynamics and local protein synthesis.
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Affiliation(s)
- Wei Wang
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Asit Rai
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Eun-Mi Hur
- Brain Science Institute-Center for Neuroscience, Korea Institute of Science and Technology, Seoul 02792, Korea Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seoul 02792, Korea Department of Neuroscience, University of Science and Technology, Daejeon 34113, Korea
| | | | - Karen T Chang
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90089 Department of Cell and Neurobiology, University of Southern California, Los Angeles, CA 90089
| | - Kyung-Tai Min
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
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15
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Wong H, Levenga J, Cain P, Rothermel B, Klann E, Hoeffer C. RCAN1 overexpression promotes age-dependent mitochondrial dysregulation related to neurodegeneration in Alzheimer's disease. Acta Neuropathol 2015; 130:829-43. [PMID: 26497675 DOI: 10.1007/s00401-015-1499-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 10/22/2022]
Abstract
Aging is the largest risk factor for Alzheimer's disease (AD). Patients with Down syndrome (DS) develop symptoms consistent with early-onset AD, suggesting that overexpression of chromosome 21 genes such as Regulator of Calcineurin 1 (RCAN1) plays a role in AD pathogenesis. RCAN1 levels are increased in the brain of DS and AD patients but also in the human brain with normal aging. RCAN1 has been implicated in several neuronal functions, but whether its increased expression is correlative or causal in the aging-related progression of AD remains elusive. We show that brain-specific overexpression of the human RCAN1.1S isoform in mice promotes early age-dependent memory and synaptic plasticity deficits, tau pathology, and dysregulation of dynamin-related protein 1 (DRP1) activity associated with mitochondrial dysfunction and oxidative stress, reproducing key AD features. Based on these findings, we propose that chronic RCAN1 overexpression during aging alters DRP1-mediated mitochondrial fission and thus acts to promote AD-related progressive neurodegeneration.
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Affiliation(s)
- Helen Wong
- Center for Neural Science, New York University, New York, NY, USA
| | - Josien Levenga
- Department of Integrated of Physiology, Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
| | - Peter Cain
- Department of Integrated of Physiology, Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
| | - Beverly Rothermel
- Department of Cardiology, University of Texas-Southwestern, Dallas, TX, USA
| | - Eric Klann
- Center for Neural Science, New York University, New York, NY, USA
| | - Charles Hoeffer
- Department of Integrated of Physiology, Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA.
- New York University School of Medicine, New York, NY, USA.
- Linda Crnic Institute, Denver, CO, USA.
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16
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Bidirectional Regulation of Amyloid Precursor Protein-Induced Memory Defects by Nebula/DSCR1: A Protein Upregulated in Alzheimer's Disease and Down Syndrome. J Neurosci 2015; 35:11374-83. [PMID: 26269644 DOI: 10.1523/jneurosci.1163-15.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Aging individuals with Down syndrome (DS) have an increased risk of developing Alzheimer's disease (AD), a neurodegenerative disorder characterized by impaired memory. Memory problems in both DS and AD individuals usually develop slowly and progressively get worse with age, but the cause of this age-dependent memory impairment is not well understood. This study examines the functional interactions between Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. Using Drosophila as a model, we find that overexpression of nebula (fly homolog of DSCR1) initially protects against APP-induced memory defects by correcting calcineurin and cAMP signaling pathways but accelerates the rate of memory loss and exacerbates mitochondrial dysfunction in older animals. We report that transient upregulation of Nebula/DSCR1 or acute pharmacological inhibition of calcineurin in aged flies protected against APP-induced memory loss. Our data suggest that calcineurin dyshomeostasis underlies age-dependent memory impairments and further imply that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory impairments in AD in DS. SIGNIFICANCE STATEMENT Most Down syndrome (DS) individuals eventually develop Alzheimer's disease (AD)-like dementia, but mechanisms underlying this age-dependent memory impairment remain poorly understood. This study examines Nebula/Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. We uncover a previously unidentified role for Nebula/DSCR1 in modulating APP-induced memory defects during aging. We show that upregulation of Nebula/DSCR1, an inhibitor of calcineurin, rescues APP-induced memory defects in young flies but enhances memory loss of older flies. Excitingly, transient Nebula/DSCR1 overexpression or calcineurin inhibition in aged flies ameliorates APP-mediated memory problems. These results suggest that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory loss in DS and AD and points to correcting calcineurin signaling as a means to improve memory during aging.
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17
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Frantz LAF, Schraiber JG, Madsen O, Megens HJ, Cagan A, Bosse M, Paudel Y, Crooijmans RPMA, Larson G, Groenen MAM. Evidence of long-term gene flow and selection during domestication from analyses of Eurasian wild and domestic pig genomes. Nat Genet 2015; 47:1141-8. [PMID: 26323058 DOI: 10.1038/ng.3394] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 08/10/2015] [Indexed: 12/18/2022]
Abstract
Traditionally, the process of domestication is assumed to be initiated by humans, involve few individuals and rely on reproductive isolation between wild and domestic forms. We analyzed pig domestication using over 100 genome sequences and tested whether pig domestication followed a traditional linear model or a more complex, reticulate model. We found that the assumptions of traditional models, such as reproductive isolation and strong domestication bottlenecks, are incompatible with the genetic data. In addition, our results show that, despite gene flow, the genomes of domestic pigs have strong signatures of selection at loci that affect behavior and morphology. We argue that recurrent selection for domestic traits likely counteracted the homogenizing effect of gene flow from wild boars and created 'islands of domestication' in the genome. Our results have major ramifications for the understanding of animal domestication and suggest that future studies should employ models that do not assume reproductive isolation.
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Affiliation(s)
- Laurent A F Frantz
- Animal Breeding and Genomics Group, Wageningen University, Wageningen, the Netherlands.,Palaeogenomics and Bio-Archaeology Research Network, Research Laboratory for Archaeology and History of Art, University of Oxford, Oxford, UK
| | - Joshua G Schraiber
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California, USA.,Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Ole Madsen
- Animal Breeding and Genomics Group, Wageningen University, Wageningen, the Netherlands
| | - Hendrik-Jan Megens
- Animal Breeding and Genomics Group, Wageningen University, Wageningen, the Netherlands
| | - Alex Cagan
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Mirte Bosse
- Animal Breeding and Genomics Group, Wageningen University, Wageningen, the Netherlands
| | - Yogesh Paudel
- Animal Breeding and Genomics Group, Wageningen University, Wageningen, the Netherlands
| | | | - Greger Larson
- Palaeogenomics and Bio-Archaeology Research Network, Research Laboratory for Archaeology and History of Art, University of Oxford, Oxford, UK
| | - Martien A M Groenen
- Animal Breeding and Genomics Group, Wageningen University, Wageningen, the Netherlands
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18
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Belichenko PV, Kleschevnikov AM, Becker A, Wagner GE, Lysenko LV, Yu YE, Mobley WC. Down Syndrome Cognitive Phenotypes Modeled in Mice Trisomic for All HSA 21 Homologues. PLoS One 2015; 10:e0134861. [PMID: 26230397 PMCID: PMC4521889 DOI: 10.1371/journal.pone.0134861] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/14/2015] [Indexed: 01/01/2023] Open
Abstract
Down syndrome (DS), trisomy for chromosome 21, is the most common genetic cause of intellectual disability. The genomic regions on human chromosome 21 (HSA21) are syntenically conserved with regions on mouse chromosomes 10, 16, and 17 (Mmu10, Mmu16, and Mmu17). Recently, we created a genetic model of DS which carries engineered duplications of all three mouse syntenic regions homologous to HSA21. This 'triple trisomic' or TTS model thus represents the most complete and accurate murine model currently available for experimental studies of genotype-phenotype relationships in DS. Here we extended our initial studies of TTS mice. Locomotor activity, stereotypic and repetitive behavior, anxiety, working memory, long-term memory, and synaptic plasticity in the dentate gyrus were examined in the TTS and wild-type (WT) control mice. Changes in locomotor activity were most remarkable for a significant increase in ambulatory time and a reduction in average velocity of TTS mice. No changes were detected in repetitive and stereotypic behavior and in measures of anxiety. Working memory showed no changes when tested in Y-maze, but deficiency in a more challenging T-maze test was detected. Furthermore, long-term object recognition memory was significantly reduced in the TTS mice. These changes were accompanied by deficient long-term potentiation in the dentate gyrus, which was restored to the WT levels following blockade of GABAA receptors with picrotoxin (100 μM). TTS mice thus demonstrated a number of phenotypes characteristic of DS and may serve as a new standard by which to evaluate and direct findings in other less complete models of DS.
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Affiliation(s)
- Pavel V. Belichenko
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093–0649, United States of America
| | - Alexander M. Kleschevnikov
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093–0649, United States of America
- * E-mail:
| | - Ann Becker
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093–0649, United States of America
| | - Grant E. Wagner
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093–0649, United States of America
| | - Larisa V. Lysenko
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093–0649, United States of America
| | - Y. Eugene Yu
- Genetics Program and Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, NY, 14263, United States of America
| | - William C. Mobley
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093–0649, United States of America
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19
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Zmijewski PA, Gao LY, Saxena AR, Chavannes NK, Hushmendy SF, Bhoiwala DL, Crawford DR. Fish oil improves gene targets of Down syndrome in C57BL and BALB/c mice. Nutr Res 2015; 35:440-8. [DOI: 10.1016/j.nutres.2015.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 01/26/2023]
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20
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Bernard-Marissal N, Médard JJ, Azzedine H, Chrast R. Dysfunction in endoplasmic reticulum-mitochondria crosstalk underlies SIGMAR1 loss of function mediated motor neuron degeneration. Brain 2015; 138:875-90. [PMID: 25678561 DOI: 10.1093/brain/awv008] [Citation(s) in RCA: 160] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Mutations in Sigma 1 receptor (SIGMAR1) have been previously identified in patients with amyotrophic lateral sclerosis and disruption of Sigmar1 in mouse leads to locomotor deficits. However, cellular mechanisms underlying motor phenotypes in human and mouse with disturbed SIGMAR1 function have not been described so far. Here we used a combination of in vivo and in vitro approaches to investigate the role of SIGMAR1 in motor neuron biology. Characterization of Sigmar1(-/-) mice revealed that affected animals display locomotor deficits associated with muscle weakness, axonal degeneration and motor neuron loss. Using primary motor neuron cultures, we observed that pharmacological or genetic inactivation of SIGMAR1 led to motor neuron axonal degeneration followed by cell death. Disruption of SIGMAR1 function in motor neurons disturbed endoplasmic reticulum-mitochondria contacts, affected intracellular calcium signalling and was accompanied by activation of endoplasmic reticulum stress and defects in mitochondrial dynamics and transport. These defects were not observed in cultured sensory neurons, highlighting the exacerbated sensitivity of motor neurons to SIGMAR1 function. Interestingly, the inhibition of mitochondrial fission was sufficient to induce mitochondria axonal transport defects as well as axonal degeneration similar to the changes observed after SIGMAR1 inactivation or loss. Intracellular calcium scavenging and endoplasmic reticulum stress inhibition were able to restore mitochondrial function and consequently prevent motor neuron degeneration. These results uncover the cellular mechanisms underlying motor neuron degeneration mediated by loss of SIGMAR1 function and provide therapeutically relevant insight into motor neuronal diseases.
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Affiliation(s)
- Nathalie Bernard-Marissal
- 1 Department of Medical Genetics, University of Lausanne, CH-1005 Lausanne, Switzerland 2 Neurodegenerative Studies Laboratory, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jean-Jacques Médard
- 1 Department of Medical Genetics, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Hamid Azzedine
- 1 Department of Medical Genetics, University of Lausanne, CH-1005 Lausanne, Switzerland 3 Institute of Neuropathology, RWTH Aachen University, 52074 Aachen, Germany
| | - Roman Chrast
- 1 Department of Medical Genetics, University of Lausanne, CH-1005 Lausanne, Switzerland 4 Department of Neuroscience and Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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21
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Phillips M, Pozzo-Miller L. Dendritic spine dysgenesis in autism related disorders. Neurosci Lett 2015; 601:30-40. [PMID: 25578949 DOI: 10.1016/j.neulet.2015.01.011] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/31/2014] [Accepted: 01/04/2015] [Indexed: 01/22/2023]
Abstract
The activity-dependent structural and functional plasticity of dendritic spines has led to the long-standing belief that these neuronal compartments are the subcellular sites of learning and memory. Of relevance to human health, central neurons in several neuropsychiatric illnesses, including autism related disorders, have atypical numbers and morphologies of dendritic spines. These so-called dendritic spine dysgeneses found in individuals with autism related disorders are consistently replicated in experimental mouse models. Dendritic spine dysgenesis reflects the underlying synaptopathology that drives clinically relevant behavioral deficits in experimental mouse models, providing a platform for testing new therapeutic approaches. By examining molecular signaling pathways, synaptic deficits, and spine dysgenesis in experimental mouse models of autism related disorders we find strong evidence for mTOR to be a critical point of convergence and promising therapeutic target.
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Affiliation(s)
- Mary Phillips
- Department of Neurobiology, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lucas Pozzo-Miller
- Department of Neurobiology, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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22
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Wu Y, Ly PTT, Song W. Aberrant expression of RCAN1 in Alzheimer's pathogenesis: a new molecular mechanism and a novel drug target. Mol Neurobiol 2014; 50:1085-97. [PMID: 24752590 DOI: 10.1007/s12035-014-8704-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 03/31/2014] [Indexed: 01/08/2023]
Abstract
AD, a devastating neurodegenerative disorder, is the most common cause of dementia in the elderly. Patients with AD are characterized by three hallmarks of neuropathology including neuritic plaque deposition, neurofibrillary tangle formation, and neuronal loss. Growing evidences indicate that dysregulation of regulator of calcineurin 1 (RCAN1) plays an important role in the pathogenesis of AD. Aberrant RCAN1 expression facilitates neuronal apoptosis and Tau hyperphosphorylation, leading to neuronal loss and neurofibrillary tangle formation. This review aims to describe the recent advances of the regulation of RCAN1 expression and its physiological functions. Moreover, the AD risk factors-induced RCAN1 dysregulation and its role in promoting neuronal loss, synaptic impairments and neurofibrillary tangle formation are summarized. Furthermore, we provide an outlook into the effects of RCAN1 dysregulation on APP processing, Aβ generation and neuritic plaque formation, and the possible underlying mechanisms, as well as the potential of targeting RCAN1 as a new therapeutic approach.
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Affiliation(s)
- Yili Wu
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, Graduate Program in Neuroscience, The University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, Canada, V6T 1Z3
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23
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Shaw JL, Chang KT. Nebula/DSCR1 upregulation delays neurodegeneration and protects against APP-induced axonal transport defects by restoring calcineurin and GSK-3β signaling. PLoS Genet 2013; 9:e1003792. [PMID: 24086147 PMCID: PMC3784514 DOI: 10.1371/journal.pgen.1003792] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 07/29/2013] [Indexed: 01/06/2023] Open
Abstract
Post-mortem brains from Down syndrome (DS) and Alzheimer's disease (AD) patients show an upregulation of the Down syndrome critical region 1 protein (DSCR1), but its contribution to AD is not known. To gain insights into the role of DSCR1 in AD, we explored the functional interaction between DSCR1 and the amyloid precursor protein (APP), which is known to cause AD when duplicated or upregulated in DS. We find that the Drosophila homolog of DSCR1, Nebula, delays neurodegeneration and ameliorates axonal transport defects caused by APP overexpression. Live-imaging reveals that Nebula facilitates the transport of synaptic proteins and mitochondria affected by APP upregulation. Furthermore, we show that Nebula upregulation protects against axonal transport defects by restoring calcineurin and GSK-3β signaling altered by APP overexpression, thereby preserving cargo-motor interactions. As impaired transport of essential organelles caused by APP perturbation is thought to be an underlying cause of synaptic failure and neurodegeneration in AD, our findings imply that correcting calcineurin and GSK-3β signaling can prevent APP-induced pathologies. Our data further suggest that upregulation of Nebula/DSCR1 is neuroprotective in the presence of APP upregulation and provides evidence for calcineurin inhibition as a novel target for therapeutic intervention in preventing axonal transport impairments associated with AD. Alzheimer's disease (AD) is a debilitating neurodegenerative disease characterized by gradual neuronal cell loss and memory decline. Importantly, Down syndrome (DS) individuals over 40 years of age almost always develop neuropathological features of AD, although most do not develop dementia until at least two decades later. These findings suggest that DS and AD may share common genetic causes and that a neuroprotective mechanism may delay neurodegeneration and cognitive decline. It has been shown that the amyloid precursor protein (APP), which is associated with AD when duplicated and upregulated in DS, is a key gene contributing to AD pathologies and axonal transport abnormalities. Here, using fruit fly as a simple model organism, we examined the role of Down syndrome critical region 1 (DSCR1), another gene located on chromosome 21 and upregulated in both DS and AD, in modulating APP phenotypes. We find that upregulation of DSCR1 (Nebula in flies) is neuroprotective in the presence of APP upregulation. We report that nebula overexpression delays the onset of neurodegeneration and transport blockage in neuronal cells. Our results further suggest that signaling pathways downstream of DSCR1 may be potential therapeutic targets for AD.
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Affiliation(s)
- Jillian L. Shaw
- Zilkha Neurogenetic Institute and Department of Cell & Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, United States of America
| | - Karen T. Chang
- Zilkha Neurogenetic Institute and Department of Cell & Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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24
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Chang KT, Ro H, Wang W, Min KT. Meeting at the crossroads: common mechanisms in Fragile X and Down syndrome. Trends Neurosci 2013; 36:685-94. [PMID: 24075449 DOI: 10.1016/j.tins.2013.08.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 08/27/2013] [Accepted: 08/29/2013] [Indexed: 10/26/2022]
Abstract
Intellectual disability is characterized by significantly impaired cognitive abilities and is due to various etiological factors, including both genetic and non-genetic causes. Two of the most common genetic forms of intellectual disability are Fragile X syndrome (FXS) and Down syndrome (DS). Recent studies have shown that proteins altered in FXS and DS can physically interact and participate in common signaling pathways regulating dendritic spine development and local protein synthesis, thus supporting the notion that spine dysmorphogenesis and abnormal local protein synthesis may be molecular underpinnings of intellectual disability. Here we review the molecular constituents regulating local protein synthesis and spine morphology and their alterations in FXS and DS. We argue that these changes might ultimately affect synaptic homeostasis and alter cognitive performance.
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Affiliation(s)
- Karen T Chang
- Zilkha Neurogenetic Institute and Department of Cell and Neurobiology, University of Southern California, Los Angeles, CA 90033, USA
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25
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Ermak G, Davies KJA. Chronic high levels of the RCAN1-1 protein may promote neurodegeneration and Alzheimer disease. Free Radic Biol Med 2013; 62:47-51. [PMID: 23369757 PMCID: PMC4720382 DOI: 10.1016/j.freeradbiomed.2013.01.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 12/28/2012] [Accepted: 01/17/2013] [Indexed: 02/07/2023]
Abstract
The RCAN1 gene encodes three different protein isoforms: RCAN1-4, RCAN1-1L, and RCAN1-1S. RCAN1-1L is the RCAN1 isoform predominantly expressed in human brains. RCAN1 proteins have been shown to regulate various other proteins and cellular functions, including calcineurin, glycogen synthase kinase-3β (GSK-3β), the mitochondrial adenine nucleotide transporter (ANT), stress adaptation, ADP/ATP exchange in mitochondria, and the mitochondrial permeability transition pore (mtPTP). The effects of increased RCAN1 gene expression seem to depend both on the specific RCAN1 protein isoform(s) synthesized and on the length of time the level of each isoform is elevated. Transiently elevated RCAN1-4 and RCAN1-1L protein levels, lasting just a few hours, can be neuroprotective under acute stress conditions, including acute oxidative stress. We propose that, by transiently inhibiting the phosphatase calcineurin, RCAN1-4 and RCAN1-1L may reinforce and extend protective stress-adaptive cell responses. In contrast, prolonged elevation of RCAN1-1L levels is associated with the types of neurodegeneration observed in several diseases, including Alzheimer disease and Down syndrome. RCAN1-1L levels can also be increased by multiple chronic stresses and by glucocorticoids, both of which can cause neurodegeneration. Although increasing levels of RCAN1-1L for just a few months has no overtly obvious neurodegenerative effect, it does suppress neurogenesis. Longer term elevation of RCAN1-1L levels (for at least 16 months), however, can lead to the first signs of neurodegeneration. Such neurodegeneration may be precipitated by (RCAN1-1L-mediated) prolonged calcineurin inhibition and GSK-3β induction/activation, both of which promote tau hyperphosphorylation, and/or by (RCAN1-1L-mediated) effects on the mitochondrial ANT, diminished ATP/ADP ratio, opening of the mtPTP, and mitochondrial autophagy. We propose that RCAN1-1L operates through various molecular mechanisms, primarily dependent upon the length of time protein levels are elevated. We also suggest that models analyzing long-term RCAN1 gene overexpression may help us to understand the molecular mechanisms of neurodegeneration in diseases such as Alzheimer disease, Down syndrome, and possibly others.
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Affiliation(s)
- Gennady Ermak
- Ethel Percy Andrus Gerontology Center, Davis School of Gerontology, and Division of Molecular & Computational Biology, Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA 90089-0191, USA
| | - Kelvin J A Davies
- Ethel Percy Andrus Gerontology Center, Davis School of Gerontology, and Division of Molecular & Computational Biology, Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA 90089-0191, USA.
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26
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Stefos GC, Soppa U, Dierssen M, Becker W. NGF upregulates the plasminogen activation inhibitor-1 in neurons via the calcineurin/NFAT pathway and the Down syndrome-related proteins DYRK1A and RCAN1 attenuate this effect. PLoS One 2013; 8:e67470. [PMID: 23825664 PMCID: PMC3692457 DOI: 10.1371/journal.pone.0067470] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 05/18/2013] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Plasminogen activator inhibitor 1 (PAI-1) is a key regulator of the plasminogen activation system. Although several lines of evidence support a significant role of PAI-1 in the brain, the regulation of its expression in neurons is poorly understood. In the present study we tested the hypothesis that NGF induces the upregulation of PAI-1 via the calcineurin/nuclear factor of activated T cells (NFAT) pathway and analysed whether the overexpression of the Down syndrome-related proteins DYRK1A and RCAN1 modulated the effect of NGF on PAI-1 expression. RESULTS NGF upregulated PAI-1 mRNA levels in primary mouse hippocampal neurons cultured for 3 days in vitro and in the rat pheochromocytoma cell line PC12. Reporter gene assays revealed that NGF activated the calcineurin/NFAT pathway in PC12 cells. Induction of PAI-1 by NGF was sensitive to the calcineurin inhibitor FK506 and the specific inhibition of NFAT activation by the cell permeable VIVIT peptide. Activation of calcineurin/NFAT signalling through other stimuli resulted in a much weaker induction of PAI-1 expression, suggesting that other NGF-induced pathways are involved in PAI-1 upregulation. Overexpression of either DYRK1A or RCAN1 negatively regulated NFAT-dependent transcriptional activity and reduced the upregulation of PAI-1 levels by NGF. CONCLUSION The present results show that the calcineurin/NFAT pathway mediates the upregulation of PAI-1 by NGF. The negative effect of DYRK1A and RCAN1 overexpression on NGF signal transduction in neural cells may contribute to the altered neurodevelopment and brain function in Down syndrome.
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Affiliation(s)
- Georgios C Stefos
- Institute of Pharmacology and Toxicology, Medical Faculty of the RWTH Aachen University, Aachen, Germany.
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27
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Daroles L, Caillé I. [Dendritic spines and local protein synthesis contribute to Down and fragile X syndromes]. Med Sci (Paris) 2013; 29:17-9. [PMID: 23351686 DOI: 10.1051/medsci/2013291005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Wu Y, Song W. Regulation of RCAN1 translation and its role in oxidative stress-induced apoptosis. FASEB J 2012; 27:208-21. [PMID: 23038757 DOI: 10.1096/fj.12-213124] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abnormal expression of regulator of calcineurin 1 (RCAN1) has been implicated in Alzheimer's disease (AD) and Down's syndrome (DS). There are two major isoforms of RCAN1, isoforms 1 and 4. RCAN1 isoform 1 is predominantly expressed in the brain, particularly in neurons. In this report, we showed that there are two translation start codons in RCAN1 exon 1 serving as a functional translation initiation site to generate a longer 41-kDa isoform 1 (RCAN1.1L) and a shorter 31-kDa isoform 1 (RCAN1.1S). The first translation initiation site has higher translation efficiency than the downstream second one, and the translation initiation of two AUG sites is by a Cap-dependent mechanism. Short-term expression of RCAN1.1L protected SH-SY5Y cells from oxidative stress-induced apoptosis by inhibiting caspase-3 activation. However, long-term accumulation of RCAN1.1L in SH-SY5Y cells promoted oxidative stress-induced apoptosis via caspase-3 activation, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay showed that the apoptosis ratio was increased to 499.03 ± 47.56% in SH-1.1L cells compared with 283.93 ± 28.66% in control cells. Furthermore, we found that RCAN1.1L is significantly elevated in the AD brains and patients with DS. RCAN1.1S is expressed at a low level in both human cells and brain tissues. Our results defined the regulatory mechanism underlying RCAN1 expression and the roles of RCAN1.1 in oxidative stress-induced neurodegeneration in AD and DS pathogenesis.
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Affiliation(s)
- Yili Wu
- Chongqing City Key Lab of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
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29
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Herault Y, Duchon A, Velot E, Maréchal D, Brault V. The in vivo Down syndrome genomic library in mouse. PROGRESS IN BRAIN RESEARCH 2012; 197:169-97. [PMID: 22541293 DOI: 10.1016/b978-0-444-54299-1.00009-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mouse models are key elements to better understand the genotype-phenotype relationship and the physiopathology of Down syndrome (DS). Even though the mouse will never recapitulate the whole spectrum of intellectual disabilities observed in the DS, mouse models have been developed over the recent decades and have been used extensively to identify homologous genes or entire regions homologous to the human chromosome 21 (Hsa21) that are necessary or sufficient to induce DS cognitive features. In this chapter, we review the principal mouse DS models which have been selected and engineered over the years either for large genomic regions or for a few or a single gene of interest. Their analyses highlight the complexity of the genetic interactions that are involved in DS cognitive phenotypes and also strengthen the hypothesis on the multigenic nature of DS. This review also addresses future research challenges relative to the making of new models and their combination to go further in the characterization of candidates and modifier of the DS features.
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Affiliation(s)
- Yann Herault
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Translational medicine and Neurogenetics program, IGBMC, CNRS, INSERM, Université de Strasbourg, UMR7104, UMR964, Illkirch, Strasbourg, France.
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30
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Wang W, Zhu JZ, Chang KT, Min KT. DSCR1 interacts with FMRP and is required for spine morphogenesis and local protein synthesis. EMBO J 2012; 31:3655-66. [PMID: 22863780 DOI: 10.1038/emboj.2012.190] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 06/18/2012] [Indexed: 12/25/2022] Open
Abstract
Most common genetic factors known to cause intellectual disability are Down syndrome and Fragile X syndrome. However, the underlying cellular and molecular mechanisms of intellectual disability remain unclear. Recently, dendritic spine dysmorphogenesis and impaired local protein synthesis are posited to contribute to the cellular mechanisms of intellectual disability. Here, we show that Down syndrome critical region1 (DSCR1) interacts with Fragile X mental retardation protein (FMRP) and regulates both dendritic spine morphogenesis and local protein synthesis. Interestingly, decreasing the level of FMRP restores the DSCR1-induced changes in dendritic spine morphology. Our results imply that DSCR1 is a novel regulator of FMRP and that Fragile X syndrome and Down syndrome may share disturbances in common pathways that regulate dendritic spine morphology and local protein synthesis.
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Affiliation(s)
- Wei Wang
- Department of Biology, Indiana University, Bloomington, USA
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31
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Martin KR, Corlett A, Dubach D, Mustafa T, Coleman HA, Parkington HC, Merson TD, Bourne JA, Porta S, Arbonés ML, Finkelstein DI, Pritchard MA. Over-expression of RCAN1 causes Down syndrome-like hippocampal deficits that alter learning and memory. Hum Mol Genet 2012; 21:3025-41. [PMID: 22511596 DOI: 10.1093/hmg/dds134] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
People with Down syndrome (DS) exhibit abnormal brain structure. Alterations affecting neurotransmission and signalling pathways that govern brain function are also evident. A large number of genes are simultaneously expressed at abnormal levels in DS; therefore, it is a challenge to determine which gene(s) contribute to specific abnormalities, and then identify the key molecular pathways involved. We generated RCAN1-TG mice to study the consequences of RCAN1 over-expression and investigate the contribution of RCAN1 to the brain phenotype of DS. RCAN1-TG mice exhibit structural brain abnormalities in those areas affected in DS. The volume and number of neurons within the hippocampus is reduced and this correlates with a defect in adult neurogenesis. The density of dendritic spines on RCAN1-TG hippocampal pyramidal neurons is also reduced. Deficits in hippocampal-dependent learning and short- and long-term memory are accompanied by a failure to maintain long-term potentiation (LTP) in hippocampal slices. In response to LTP induction, we observed diminished calcium transients and decreased phosphorylation of CaMKII and ERK1/2-proteins that are essential for the maintenance of LTP and formation of memory. Our data strongly suggest that RCAN1 plays an important role in normal brain development and function and its up-regulation likely contributes to the neural deficits associated with DS.
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Affiliation(s)
- Katherine R Martin
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, 3168 Victoria, Australia
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32
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The use of mouse models for understanding the biology of down syndrome and aging. Curr Gerontol Geriatr Res 2012; 2012:717315. [PMID: 22461792 PMCID: PMC3296169 DOI: 10.1155/2012/717315] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Accepted: 12/06/2011] [Indexed: 12/16/2022] Open
Abstract
Down syndrome is a complex condition caused by trisomy of human chromosome 21. The biology of aging may be different in individuals with Down syndrome; this is not well understood in any organism. Because of its complexity, many aspects of Down syndrome must be studied either in humans or in animal models. Studies in humans are essential but are limited for ethical and practical reasons. Fortunately, genetically altered mice can serve as extremely useful models of Down syndrome, and progress in their production and analysis has been remarkable. Here, we describe various mouse models that have been used to study Down syndrome. We focus on segmental trisomies of mouse chromosome regions syntenic to human chromosome 21, mice in which individual genes have been introduced, or mice in which genes have been silenced by targeted mutagenesis. We selected a limited number of genes for which considerable evidence links them to aspects of Down syndrome, and about which much is known regarding their function. We focused on genes important for brain and cognitive function, and for the altered cancer spectrum seen in individuals with Down syndrome. We conclude with observations on the usefulness of mouse models and speculation on future directions.
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33
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Kleschevnikov AM, Belichenko PV, Salehi A, Wu C. Discoveries in Down syndrome: moving basic science to clinical care. PROGRESS IN BRAIN RESEARCH 2012; 197:199-221. [PMID: 22541294 DOI: 10.1016/b978-0-444-54299-1.00010-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This review describes recent discoveries in neurobiology of Down syndrome (DS) achieved with use of mouse genetic models and provides an overview of experimental approaches aimed at development of pharmacological restoration of cognitive function in people with this developmental disorder. Changes in structure and function of synaptic connections within the hippocampal formation of DS model mice, as well as alterations in innervations of the hippocampus by noradrenergic and cholinergic neuromodulatory systems, provided important clues for potential pharmacological treatments of cognitive disabilities in DS. Possible molecular and cellular mechanisms underlying this genetic disorder have been addressed. We discuss novel mechanisms engaging misprocessing of amyloid precursor protein (App) and other proteins, through their affect on axonal transport and endosomal dysfunction, to "Alzheimer-type" neurodegenerative processes that affect cognition later in life. In conclusion, a number of therapeutic strategies have been defined that may restore cognitive function in mouse models of DS. In the juvenile and young animals, these strategists focus on restoration of synaptic plasticity, rate of adult neurogenesis, and functions of the neuromodulatory subcortical systems. Later in life, the major focus is on recuperation of misprocessed App and related proteins. It is hoped that the identification of an increasing number of potential targets for pharmacotherapy of cognitive deficits in DS will add to the momentum for creating and completing clinical trials.
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Affiliation(s)
- A M Kleschevnikov
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.
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