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Mutations in CRADD Result in Reduced Caspase-2-Mediated Neuronal Apoptosis and Cause Megalencephaly with a Rare Lissencephaly Variant. Am J Hum Genet 2016; 99:1117-1129. [PMID: 27773430 PMCID: PMC5097945 DOI: 10.1016/j.ajhg.2016.09.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 09/19/2016] [Indexed: 12/02/2022] Open
Abstract
Lissencephaly is a malformation of cortical development typically caused by deficient neuronal migration resulting in cortical thickening and reduced gyration. Here we describe a “thin” lissencephaly (TLIS) variant characterized by megalencephaly, frontal predominant pachygyria, intellectual disability, and seizures. Trio-based whole-exome sequencing and targeted re-sequencing identified recessive mutations of CRADD in six individuals with TLIS from four unrelated families of diverse ethnic backgrounds. CRADD (also known as RAIDD) is a death-domain-containing adaptor protein that oligomerizes with PIDD and caspase-2 to initiate apoptosis. TLIS variants cluster in the CRADD death domain, a platform for interaction with other death-domain-containing proteins including PIDD. Although caspase-2 is expressed in the developing mammalian brain, little is known about its role in cortical development. CRADD/caspase-2 signaling is implicated in neurotrophic factor withdrawal- and amyloid-β-induced dendritic spine collapse and neuronal apoptosis, suggesting a role in cortical sculpting and plasticity. TLIS-associated CRADD variants do not disrupt interactions with caspase-2 or PIDD in co-immunoprecipitation assays, but still abolish CRADD’s ability to activate caspase-2, resulting in reduced neuronal apoptosis in vitro. Homozygous Cradd knockout mice display megalencephaly and seizures without obvious defects in cortical lamination, supporting a role for CRADD/caspase-2 signaling in mammalian brain development. Megalencephaly and lissencephaly associated with defective programmed cell death from loss of CRADD function in humans implicate reduced apoptosis as an important pathophysiological mechanism of cortical malformation. Our data suggest that CRADD/caspase-2 signaling is critical for normal gyration of the developing human neocortex and for normal cognitive ability.
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102
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FAIM-L regulation of XIAP degradation modulates Synaptic Long-Term Depression and Axon Degeneration. Sci Rep 2016; 6:35775. [PMID: 27767058 PMCID: PMC5073314 DOI: 10.1038/srep35775] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 10/05/2016] [Indexed: 12/19/2022] Open
Abstract
Caspases have recently emerged as key regulators of axonal pruning and degeneration and of long-term depression (LTD), a long-lasting form of synaptic plasticity. However, the mechanism underlying these functions remains unclear. In this context, XIAP has been shown to modulate these processes. The neuron-specific form of FAIM protein (FAIM-L) is a death receptor antagonist that stabilizes XIAP protein levels, thus preventing death receptor-induced neuronal apoptosis. Here we show that FAIM-L modulates synaptic transmission, prevents chemical-LTD induction in hippocampal neurons, and thwarts axon degeneration after nerve growth factor (NGF) withdrawal. Additionally, we demonstrate that the participation of FAIM-L in these two processes is dependent on its capacity to stabilize XIAP protein levels. Our data reveal FAIM-L as a regulator of axonal degeneration and synaptic plasticity.
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103
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Martirosian V, Chen TC, Lin M, Neman J. Medulloblastoma initiation and spread: Where neurodevelopment, microenvironment and cancer cross pathways. J Neurosci Res 2016; 94:1511-1519. [DOI: 10.1002/jnr.23917] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/18/2016] [Accepted: 08/19/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Vahan Martirosian
- Department of Neurosurgery, Keck School of Medicine; University of Southern California; Los Angeles California
| | - Thomas C. Chen
- Department of Neurosurgery, Keck School of Medicine; University of Southern California; Los Angeles California
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California; Los Angeles California
| | - Michelle Lin
- Department of Neurosurgery, Keck School of Medicine; University of Southern California; Los Angeles California
| | - Josh Neman
- Department of Neurosurgery, Keck School of Medicine; University of Southern California; Los Angeles California
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California; Los Angeles California
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104
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Creeley CE. From Drug-Induced Developmental Neuroapoptosis to Pediatric Anesthetic Neurotoxicity-Where Are We Now? Brain Sci 2016; 6:brainsci6030032. [PMID: 27537919 PMCID: PMC5039461 DOI: 10.3390/brainsci6030032] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/05/2016] [Accepted: 08/12/2016] [Indexed: 01/02/2023] Open
Abstract
The fetal and neonatal periods are critical and sensitive periods for neurodevelopment, and involve rapid brain growth in addition to natural programmed cell death (i.e., apoptosis) and synaptic pruning. Apoptosis is an important process for neurodevelopment, preventing redundant, faulty, or unused neurons from cluttering the developing brain. However, animal studies have shown massive neuronal cell death by apoptosis can also be caused by exposure to several classes of drugs, namely gamma-aminobutyric acid (GABA) agonists and N-methyl-d-aspartate (NMDA) antagonists that are commonly used in pediatric anesthesia. This form of neurotoxic insult could cause a major disruption in brain development with the potential to permanently shape behavior and cognitive ability. Evidence does suggest that psychoactive drugs alter neurodevelopment and synaptic plasticity in the animal brain, which, in the human brain, may translate to permanent neurodevelopmental changes associated with long-term intellectual disability. This paper reviews the seminal animal research on drug-induced developmental apoptosis and the subsequent clinical studies that have been conducted thus far. In humans, there is growing evidence that suggests anesthetics have the potential to harm the developing brain, but the long-term outcome is not definitive and causality has not been determined. The consensus is that there is more work to be done using both animal models and human clinical studies.
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Affiliation(s)
- Catherine E Creeley
- Department of Psychology, State University of New York at Fredonia, Fredonia, NY 14063, USA.
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105
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Abstract
The nerve growth factor family of growth factors, collectively known as neurotrophins, are evolutionarily ancient regulators with an enormous range of biological functions. Reflecting this long history and functional diversity, mechanisms for cellular responses to neurotrophins are exceptionally complex. Neurotrophins signal through p75
NTR, a member of the TNF receptor superfamily member, and through receptor tyrosine kinases (TrkA, TrkB, TrkC), often with opposite functional outcomes. The two classes of receptors are activated preferentially by proneurotrophins and mature processed neurotrophins, respectively. However, both receptor classes also possess neurotrophin-independent signaling functions. Signaling functions of p75
NTR and Trk receptors are each influenced by the other class of receptors. This review focuses on the mechanisms responsible for the functional interplay between the two neurotrophin receptor signaling systems.
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Affiliation(s)
- Mark Bothwell
- Department of Physiology & Biophysics, University of Washington, Seattle, WA, USA
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106
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Patak J, Hess JL, Zhang-James Y, Glatt SJ, Faraone SV. SLC9A9 Co-expression modules in autism-associated brain regions. Autism Res 2016; 10:414-429. [PMID: 27439572 DOI: 10.1002/aur.1670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 05/27/2016] [Accepted: 06/13/2016] [Indexed: 12/16/2022]
Abstract
SLC9A9 is a sodium hydrogen exchanger present in the recycling endosome and highly expressed in the brain. It is implicated in neuropsychiatric disorders, including autism spectrum disorders (ASDs). Little research concerning its gene expression patterns and biological pathways has been conducted. We sought to investigate its possible biological roles in autism-associated brain regions throughout development. We conducted a weighted gene co-expression network analysis on RNA-seq data downloaded from Brainspan. We compared prenatal and postnatal gene expression networks for three ASD-associated brain regions known to have high SLC9A9 gene expression. We also performed an ASD-associated single nucleotide polymorphism enrichment analysis and a cell signature enrichment analysis. The modules showed differences in gene constituents (membership), gene number, and connectivity throughout time. SLC9A9 was highly associated with immune system functions, metabolism, apoptosis, endocytosis, and signaling cascades. Gene list comparison with co-immunoprecipitation data was significant for multiple modules. We found a disproportionately high autism risk signal among genes constituting the prenatal hippocampal module. The modules were enriched with astrocyte and oligodendrocyte markers. SLC9A9 is potentially involved in the pathophysiology of ASDs. Our investigation confirmed proposed functions for SLC9A9, such as endocytosis and immune regulation, while also revealing potential roles in mTOR signaling and cell survival.. By providing a concise molecular map and interactions, evidence of cell type and implicated brain regions we hope this will guide future research on SLC9A9. Autism Res 2017, 10: 414-429. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.
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Affiliation(s)
- Jameson Patak
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York
| | - Jonathan L Hess
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York
| | - Yanli Zhang-James
- Department of Psychiatry, Upstate Medical University, Syracuse, New York
| | - Stephen J Glatt
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York.,Department of Psychiatry, Upstate Medical University, Syracuse, New York
| | - Stephen V Faraone
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York.,Department of Psychiatry, Upstate Medical University, Syracuse, New York.,Department of Biomedicine, K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
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107
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Casano A, Albert M, Peri F. Developmental Apoptosis Mediates Entry and Positioning of Microglia in the Zebrafish Brain. Cell Rep 2016; 16:897-906. [DOI: 10.1016/j.celrep.2016.06.033] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 04/11/2016] [Accepted: 06/03/2016] [Indexed: 01/15/2023] Open
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108
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Hwang JY, Lee J, Oh CK, Kang HW, Hwang IY, Um JW, Park HC, Kim S, Shin JH, Park WY, Darnell RB, Um HD, Chung KC, Kim K, Oh YJ. Proteolytic degradation and potential role of onconeural protein cdr2 in neurodegeneration. Cell Death Dis 2016; 7:e2240. [PMID: 27253404 PMCID: PMC5143381 DOI: 10.1038/cddis.2016.151] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/21/2016] [Accepted: 05/05/2016] [Indexed: 12/11/2022]
Abstract
Cerebellar degeneration-related protein 2 (cdr2) is expressed in the central nervous system, and its ectopic expression in tumor cells of patients with gynecological malignancies elicits immune responses by cdr2-specific autoantibodies and T lymphocytes, leading to neurological symptoms. However, little is known about the regulation and function of cdr2 in neurodegenerative diseases. Because we found that cdr2 is highly expressed in the midbrain, we investigated the role of cdr2 in experimental models of Parkinson's disease (PD). We found that cdr2 levels were significantly reduced after stereotaxic injection of 1-methyl-4-phenylpyridinium (MPP(+)) into the striatum. cdr2 levels were also decreased in the brains of post-mortem PD patients. Using primary cultures of mesencephalic neurons and MN9D cells, we confirmed that MPP(+) reduces cdr2 in tyrosine hydroxylase-positive dopaminergic neuronal cells. The MPP(+)-induced decrease of cdr2 was primarily caused by calpain- and ubiquitin proteasome system-mediated degradation, and cotreatment with pharmacological inhibitors of these enzymes or overexpression of calcium-binding protein rendered cells less vulnerable to MPP(+)-mediated cytotoxicity. Consequently, overexpression of cdr2 rescued cells from MPP(+)-induced cytotoxicity, whereas knockdown of cdr2 accelerated toxicity. Collectively, our findings provide insights into the novel regulatory mechanism and potentially protective role of onconeural protein during dopaminergic neurodegeneration.
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Affiliation(s)
- J-Y Hwang
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea.,Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - J Lee
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea
| | - C-K Oh
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea
| | - H W Kang
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea
| | - I-Y Hwang
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea
| | - J W Um
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea
| | - H C Park
- Graduate School of Medicine, Korea University, Ansan 425-707, Gyeonggi-do, Korea
| | - S Kim
- Graduate School of Medicine, Korea University, Ansan 425-707, Gyeonggi-do, Korea
| | - J-H Shin
- Division of Pharmacology, Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 440-746, Gyeonggi-do, Korea
| | - W-Y Park
- Division of Pharmacology, Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 440-746, Gyeonggi-do, Korea
| | - R B Darnell
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
| | - H-D Um
- Division of Radiation Cancer Biology, Korean Institute of Radiological & Medical Sciences, Seoul 01812, Korea
| | - K C Chung
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea
| | - K Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873, Korea
| | - Y J Oh
- Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 120-749, Korea
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109
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Triana-Martínez F, Pedraza-Vázquez G, Maciel-Barón LA, Königsberg M. Reflections on the role of senescence during development and aging. Arch Biochem Biophys 2016; 598:40-9. [PMID: 27059850 DOI: 10.1016/j.abb.2016.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 04/02/2016] [Accepted: 04/04/2016] [Indexed: 01/07/2023]
Abstract
New and stimulating results have challenged the concept that cellular senescence might not be synonymous with aging. It is indisputable that during aging, senescent cell accumulation has an impact on organismal health. Nevertheless, senescent cells are now known to display physiological roles during embryonic development, during wound healing repair and as a cellular response to stress. The fact that senescence has been found in cells that did not attain their maximal round of replications, nor have metabolic alterations or DNA damage, also challenges the paradigm that senescence is cellular aging, and it is in favor of the idea that cellular senescence is a phenomenon that has a function by itself. Therefore, in order to understand this phenomenon it is important to analyze the relationship between senescence and other cellular responses that have many features in common, such as apoptosis, cancer and autophagy, particularly highlighting their role during development and adulthood.
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Affiliation(s)
- F Triana-Martínez
- Dept. Ciencias de la Salud, DCBS, Universidad Autónoma Metropolitana Iztapalapa, México D.F. 09340, Mexico
| | - G Pedraza-Vázquez
- Dept. Ciencias de la Salud, DCBS, Universidad Autónoma Metropolitana Iztapalapa, México D.F. 09340, Mexico
| | - L A Maciel-Barón
- Dept. Ciencias de la Salud, DCBS, Universidad Autónoma Metropolitana Iztapalapa, México D.F. 09340, Mexico
| | - M Königsberg
- Dept. Ciencias de la Salud, DCBS, Universidad Autónoma Metropolitana Iztapalapa, México D.F. 09340, Mexico.
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110
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Tung YT, Lu YL, Peng KC, Yen YP, Chang M, Li J, Jung H, Thams S, Huang YP, Hung JH, Chen JA. Mir-17∼92 Governs Motor Neuron Subtype Survival by Mediating Nuclear PTEN. Cell Rep 2016; 11:1305-18. [PMID: 26004179 DOI: 10.1016/j.celrep.2015.04.050] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 03/17/2015] [Accepted: 04/22/2015] [Indexed: 01/07/2023] Open
Abstract
Motor neurons (MNs) are unique because they project their axons outside of the CNS to innervate the peripheral muscles. Limb-innervating lateral motor column MNs (LMC-MNs) travel substantially to innervate distal limb mesenchyme. How LMC-MNs fine-tune the balance between survival and apoptosis while wiring the sensorimotor circuit en route remains unclear. Here, we show that the mir-17∼92 cluster is enriched in embryonic stem cell (ESC)-derived LMC-MNs and that conditional mir-17∼92 deletion in MNs results in the death of LMC-MNs in vitro and in vivo. mir-17∼92 overexpression rescues MNs from apoptosis, which occurs spontaneously during embryonic development. PTEN is a primary target of mir-17∼92 responsible for LMC-MN degeneration. Additionally, mir-17∼92 directly targets components of E3 ubiquitin ligases, affecting PTEN subcellular localization through monoubiquitination. This miRNA-mediated regulation modulates both target expression and target subcellular localization, providing LMC-MNs with an intricate defensive mechanism that controls their survival.
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111
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Barnstable CJ, Reddy R, Li H, Horvath TL. Mitochondrial Uncoupling Protein 2 (UCP2) Regulates Retinal Ganglion Cell Number and Survival. J Mol Neurosci 2016; 58:461-9. [PMID: 26846222 PMCID: PMC4833669 DOI: 10.1007/s12031-016-0728-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 01/27/2016] [Indexed: 12/29/2022]
Abstract
In the brain, mitochondrial uncoupling protein 2 (UCP2) has emerged as a stress signal associated with neuronal survival. In the retina, UCP2 is expressed primarily by retinal ganglion cells. Here, we investigated the functional relevance of UCP2 in the mouse retina. Increased expression of UCP2 significantly reduced apoptosis during the critical developmental period resulting in elevated numbers of retinal ganglion cells in the adult. Elevated UCP2 levels also protected against excitotoxic cell death induced by intraocular injection of either NMDA or kainic acid. In monolayer cultures of retinal cells, elevated UCP2 levels increased cell survival and rendered the cells independent of the survival-promoting effects of the neurotrophic factors BDNF and CNTF. Taken together, these data implicate UCP2 as an important regulator of retinal neuron survival both during development and in adult animals.
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Affiliation(s)
- Colin J Barnstable
- Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT, 06510, USA.
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT, 06510, USA.
- Department of Neural and Behavioral Science, Penn State University College of Medicine, H109, 500 University Drive, Hershey, PA, 17033, USA.
| | - Rajini Reddy
- Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Hong Li
- Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT, 06510, USA
- Department of Neural and Behavioral Science, Penn State University College of Medicine, H109, 500 University Drive, Hershey, PA, 17033, USA
| | - Tamas L Horvath
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT, 06510, USA
- Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, 06510, USA
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
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112
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Duzel E, van Praag H, Sendtner M. Can physical exercise in old age improve memory and hippocampal function? Brain 2016; 139:662-73. [PMID: 26912638 PMCID: PMC4766381 DOI: 10.1093/brain/awv407] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/19/2015] [Accepted: 12/21/2015] [Indexed: 01/19/2023] Open
Abstract
Physical exercise can convey a protective effect against cognitive decline in ageing and Alzheimer's disease. While the long-term health-promoting and protective effects of exercise are encouraging, it's potential to induce neuronal and vascular plasticity in the ageing brain is still poorly understood. It remains unclear whether exercise slows the trajectory of normal ageing by modifying vascular and metabolic risk factors and/or consistently boosts brain function by inducing structural and neurochemical changes in the hippocampus and related medial temporal lobe circuitry-brain areas that are important for learning and memory. Hence, it remains to be established to what extent exercise interventions in old age can improve brain plasticity above and beyond preservation of function. Existing data suggest that exercise trials aiming for improvement and preservation may require different outcome measures and that the balance between the two may depend on exercise intensity and duration, the presence of preclinical Alzheimer's disease pathology, vascular and metabolic risk factors and genetic variability.
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Affiliation(s)
- Emrah Duzel
- 1 Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany 2 German Center for Neurodegenerative Diseases (DZNE), Leipziger Str. 44, 39120 Magdeburg, Germany 3 Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, UK
| | - Henriette van Praag
- 4 Neuroplasticity and Behavior Unit, Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Michael Sendtner
- 5 Institute of Clinical Neurobiology, University of Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
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113
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Calpain-1 and Calpain-2: The Yin and Yang of Synaptic Plasticity and Neurodegeneration. Trends Neurosci 2016; 39:235-245. [PMID: 26874794 DOI: 10.1016/j.tins.2016.01.007] [Citation(s) in RCA: 166] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/20/2016] [Accepted: 01/21/2016] [Indexed: 01/09/2023]
Abstract
Many signaling pathways participate in both synaptic plasticity and neuronal degeneration. While calpains participate in these phenomena, very few studies have evaluated the respective roles of the two major calpain isoforms in the brain, calpain-1 and calpain-2. We review recent studies indicating that calpain-1 and calpain-2 exhibit opposite functions in both synaptic plasticity and neurodegeneration. Calpain-1 activation is required for the induction of long-term potentiation (LTP) and is generally neuroprotective, while calpain-2 activation limits the extent of potentiation and is neurodegenerative. This duality of functions is related to their associations with different PDZ-binding proteins, resulting in differential subcellular localization, and offers new therapeutic opportunities for a number of indications in which these proteases have previously been implicated.
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114
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WANG HUA, WU JINLIN. 17β-estradiol suppresses hyperoxia-induced apoptosis of oligodendrocytes through paired-immunoglobulin-like receptor B. Mol Med Rep 2016; 13:2892-8. [DOI: 10.3892/mmr.2016.4808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 01/05/2016] [Indexed: 11/06/2022] Open
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115
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MENSHANOV PN, LANSHAKOV DA, DYGALO NN. proBDNF Is a Major Product of bdnf Gene Expressed in the Perinatal Rat Cortex. Physiol Res 2015; 64:925-34. [DOI: 10.33549/physiolres.932996] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In the developing brain, mature brain derived neurotrophic factor (mBDNF) and its precursor (proBDNF) exhibit prosurvival and proapoptotic functions, respectively. However, it is still unknown whether mBDNF or proBDNF is a major form of neurotrophin expressed in the immature brain, as well as if the level of active caspase-3 correlates with the levels of BDNF forms during normal brain development. Here we found that both proBDNF and mBDNF were expressed abundantly in the rat brainstem, hippocampus and cerebellum between embryonic day 20 and postnatal day 8. The levels of mature neurotrophin as well as mBDNF to proBDNF ratios negatively correlated with the expression of active caspase-3 across brain regions. The immature cortex was the only structure, in which proBDNF was the major product of bdnf gene, especially in the cortical layers 2-3. And only in the cortex, the expression of BDNF precursor positively correlated with the levels of active caspase-3. These findings suggest that proBDNF alone may play an important role in the regulation of naturally occurring cell death during cortical development.
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Affiliation(s)
- P. N. MENSHANOV
- Functional Neurogenomics Laboratory, Institute of Cytology and Genetics Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russian Federation
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116
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Tovar-y-Romo LB, Penagos-Puig A, Ramírez-Jarquín JO. Endogenous recovery after brain damage: molecular mechanisms that balance neuronal life/death fate. J Neurochem 2015; 136:13-27. [PMID: 26376102 DOI: 10.1111/jnc.13362] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 07/27/2015] [Accepted: 08/25/2015] [Indexed: 01/08/2023]
Abstract
Neuronal survival depends on multiple factors that comprise a well-fueled energy metabolism, trophic input, clearance of toxic substances, appropriate redox environment, integrity of blood-brain barrier, suppression of programmed cell death pathways and cell cycle arrest. Disturbances of brain homeostasis lead to acute or chronic alterations that might ultimately cause neuronal death with consequent impairment of neurological function. Although we understand most of these processes well when they occur independently from one another, we still lack a clear grasp of the concerted cellular and molecular mechanisms activated upon neuronal damage that intervene in protecting damaged neurons from death. In this review, we summarize a handful of endogenously activated mechanisms that balance molecular cues so as to determine whether neurons recover from injury or die. We center our discussion on mechanisms that have been identified to participate in stroke, although we consider different scenarios of chronic neurodegeneration as well. We discuss two central processes that are involved in endogenous repair and that, when not regulated, could lead to tissue damage, namely, trophic support and neuroinflammation. We emphasize the need to construct integrated models of neuronal degeneration and survival that, in the end, converge in neuronal fate after injury. Under neurodegenerative conditions, endogenously activated mechanisms balance out molecular cues that determine whether neurons contend toxicity or die. Many processes involved in endogenous repair may as well lead to tissue damage depending on the strength of stimuli. Signaling mediated by trophic factors and neuroinflammation are examples of these processes as they regulate different mechanisms that mediate neuronal demise including necrosis, apoptosis, necroptosis, pyroptosis and autophagy. In this review, we discuss recent findings on balanced regulation and their involvement in neuronal death.
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Affiliation(s)
- Luis B Tovar-y-Romo
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F., México
| | - Andrés Penagos-Puig
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F., México
| | - Josué O Ramírez-Jarquín
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F., México
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117
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Akagawa H, Hara Y, Togane Y, Iwabuchi K, Hiraoka T, Tsujimura H. The role of the effector caspases drICE and dcp-1 for cell death and corpse clearance in the developing optic lobe in Drosophila. Dev Biol 2015; 404:61-75. [PMID: 26022392 DOI: 10.1016/j.ydbio.2015.05.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 05/13/2015] [Accepted: 05/16/2015] [Indexed: 02/02/2023]
Abstract
In the developing Drosophila optic lobe, cell death occurs via apoptosis and in a distinctive spatio-temporal pattern of dying cell clusters. We analyzed the role of effector caspases drICE and dcp-1 in optic lobe cell death and subsequent corpse clearance using mutants. Neurons in many clusters required either drICE or dcp-1 and each one is sufficient. This suggests that drICE and dcp-1 function in cell death redundantly. However, dying neurons in a few clusters strictly required drICE but not dcp-1, but required drICE and dcp-1 when drICE activity was reduced via hypomorphic mutation. In addition, analysis of the mutants suggests an important role of effecter caspases in corpse clearance. In both null and hypomorphic drICE mutants, greater number of TUNEL-positive cells were observed than in wild type, and many TUNEL-positive cells remained until later stages. Lysotracker staining showed that there was a defect in corpse clearance in these mutants. All the results suggested that drICE plays an important role in activating corpse clearance in dying cells, and that an additional function of effector caspases is required for the activation of corpse clearance as well as that for carrying out cell death.
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Affiliation(s)
- Hiromi Akagawa
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Biological Production Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Yusuke Hara
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Yu Togane
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Kikuo Iwabuchi
- Department of Biological Production Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Tsuyoshi Hiraoka
- Department of Biological Production Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hidenobu Tsujimura
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
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Klistorner A, Vootakuru N, Wang C, Yiannikas C, Graham SL, Parratt J, Garrick R, Levin N, Masters L, Lagopoulos J, Barnett MH. Decoding diffusivity in multiple sclerosis: analysis of optic radiation lesional and non-lesional white matter. PLoS One 2015; 10:e0122114. [PMID: 25807541 PMCID: PMC4373765 DOI: 10.1371/journal.pone.0122114] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 02/17/2015] [Indexed: 12/19/2022] Open
Abstract
Objectives Diffusion tensor imaging (DTI) has been suggested as a new promising tool in MS that may provide greater pathological specificity than conventional MRI, helping, therefore, to elucidate disease pathogenesis and monitor therapeutic efficacy. However, the pathological substrates that underpin alterations in brain tissue diffusivity are not yet fully delineated. Tract-specific DTI analysis has previously been proposed in an attempt to alleviate this problem. Here, we extended this approach by segmenting a single tract into areas bound by seemingly similar pathological processes, which may better delineate the potential association between DTI metrics and underlying tissue damage. Method Several compartments were segmented in optic radiation (OR) of 50 relapsing-remitting MS patients including T2 lesions, proximal and distal parts of fibers transected by lesion and fibers with no discernable pathology throughout the entire length of the OR. Results Asymmetry analysis between lesional and non-lesional fibers demonstrated a marked increase in Radial Diffusivity (RD), which was topographically limited to focal T2 lesions and potentially relates to the lesional myelin loss. A relative elevation of Axial Diffusivity (AD) in the distal part of the lesional fibers was observed in a distribution consistent with Wallerian degeneration, while diffusivity in the proximal portion of transected axons remained normal. A moderate, but significant elevation of RD in OR non-lesional fibers was strongly associated with the global (but not local) T2 lesion burden and is probably related to microscopic demyelination undetected by conventional MRI. Conclusion This study highlights the utility of the compartmentalization approach in elucidating the pathological substrates of diffusivity and demonstrates the presence of tissue-specific patterns of altered diffusivity in MS, providing further evidence that DTI is a sensitive marker of tissue damage in both lesions and NAWM. Our results suggest that, at least within the OR, parallel and perpendicular diffusivities are affected by tissue restructuring related to distinct pathological processes.
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Affiliation(s)
- Alexander Klistorner
- Department of Ophthalmology, Save Sight Institute, University of Sydney, Sydney, Australia
- Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
- * E-mail:
| | | | - Chenyu Wang
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW, Australia
| | | | - Stuart L. Graham
- Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
| | | | | | - Netta Levin
- Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Lynette Masters
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW, Australia
| | - Jim Lagopoulos
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW, Australia
| | - Michael H. Barnett
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW, Australia
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119
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Glazova MV, Pak ES, Murashov AK. Neurogenic potential of spinal cord organotypic culture. Neurosci Lett 2015; 594:60-5. [PMID: 25805458 DOI: 10.1016/j.neulet.2015.03.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 11/25/2022]
Abstract
There are several neurogenic niches in the adult mammalian central nervous system. In the central nervous system, neural stem cells (NSC) localize not only to the periventricular area, but are also diffusely distributed in the parenchyma. Here, we assessed neurogenic potential of organotypic cultures prepared from adult mouse spinal cord. Slices were placed on Millipore inserts for organotypic culture and incubated in neurobasal media supplemented with B27 and N2 for up to 9 weeks. After 3-4 weeks, the cell's aggregates formed in the slices. The aggregate's cells were BrdU-uptake, nestin and alkaline phosphatase positive. At the later stage of incubation, we observed Oct3/4 in the inner mass of the neurospheres as well as expression of Dppa1, which is an Oct-4 downstream target gene and a marker for pluripotency. To check differentiation, the formed neurospheres were isolated and cultured for several days in differentiation media. The obtained data demonstrated the cells from isolated neurospheres differentiate into astrocytes and MAP2-positive neurons. Immunostaining for HB9 and Lim2 revealed subsequent differentiation of MAP2-positive cells into motor neurons and interneurons, respectively. We hypothesized neuronal loss and/or long-term culturing of spinal cord slices may trigger a reset of the internal cell program and promote proliferation and further differentiation of NSC.
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Affiliation(s)
- Margarita V Glazova
- Departments of Physiology, The Brody School of Medicine, East Carolina University School of Medicine, Brody Building, 600 Moye Boulevard, Greenville, NC 27834, USA.
| | - Elena S Pak
- Departments of Physiology, The Brody School of Medicine, East Carolina University School of Medicine, Brody Building, 600 Moye Boulevard, Greenville, NC 27834, USA
| | - Alexander K Murashov
- Departments of Physiology, The Brody School of Medicine, East Carolina University School of Medicine, Brody Building, 600 Moye Boulevard, Greenville, NC 27834, USA
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120
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McWilliams TG, Howard L, Wyatt S, Davies AM. Regulation of Autocrine Signaling in Subsets of Sympathetic Neurons Has Regional Effects on Tissue Innervation. Cell Rep 2015; 10:1443-1449. [PMID: 25753410 PMCID: PMC4407286 DOI: 10.1016/j.celrep.2015.02.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 12/19/2014] [Accepted: 02/02/2015] [Indexed: 02/03/2023] Open
Abstract
The regulation of innervation by target-derived factors
like nerve growth factor (NGF) is the cornerstone of neurotrophic theory. Whereas
autocrine signaling in neurons affecting survival and axon growth has been described,
it is difficult to reconcile autocrine signaling with the idea that targets control
their innervation. Here, we report that an autocrine signaling loop in developing
mouse sympathetic neurons involving CD40L (TNFSF5) and CD40 (TNFRSF5) selectively
enhances NGF-promoted axon growth and branching, but not survival, via CD40L reverse
signaling. Because NGF negatively regulates CD40L and CD40 expression, this signaling
loop operates only in neurons exposed to low levels of NGF. Consequently, the
sympathetic innervation density of tissues expressing low NGF is significantly
reduced in CD40-deficient mice, whereas the innervation density of tissues expressing
high levels of NGF is unaffected. Our findings reveal how differential regulation of
autocrine signaling in neurons has region-specific effects on axon growth and tissue
innervation. CD40/CD40L autocrine signaling enhances NGF-promoted
sympathetic axon growth NGF negatively regulates CD40 and CD40L levels in
developing sympathetic neurons Accordingly, CD40/CD40L signaling only enhances axon growth
at low levels of NGF Innervation of tissues expressing low NGF levels is
disrupted in CD40 knockout mice
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Affiliation(s)
- Thomas G McWilliams
- Division of Molecular Biosciences, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales
| | - Laura Howard
- Division of Molecular Biosciences, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales
| | - Sean Wyatt
- Division of Molecular Biosciences, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales
| | - Alun M Davies
- Division of Molecular Biosciences, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales.
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Arya R, Sarkissian T, Tan Y, White K. Neural stem cell progeny regulate stem cell death in a Notch and Hox dependent manner. Cell Death Differ 2015; 22:1378-87. [PMID: 25633198 DOI: 10.1038/cdd.2014.235] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/02/2014] [Accepted: 12/12/2014] [Indexed: 01/05/2023] Open
Abstract
Cell death is a prevalent, well-controlled and fundamental aspect of development, particularly in the nervous system. In Drosophila, specific neural stem cells are eliminated by apoptosis during embryogenesis. In the absence of apoptosis, these stem cells continue to divide, resulting in a dramatically hyperplastic central nervous system and adult lethality. Although core cell death pathways have been well described, the spatial, temporal and cell identity cues that activate the cell death machinery in specific cells are largely unknown. We identified a cis-regulatory region that controls the transcription of the cell death activators reaper, grim and sickle exclusively in neural stem cells. Using a reporter generated from this regulatory region, we found that Notch activity is required for neural stem cell death. Notch regulates the expression of the abdominalA homeobox protein, which provides important spatial cues for death. Importantly, we show that pro-apoptotic Notch signaling is activated by the Delta ligand expressed on the neighboring progeny of the stem cell. Thus we identify a previously undescribed role for progeny in regulating the proper developmental death of their parental stem cells.
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Affiliation(s)
- R Arya
- CBRC, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA
| | - T Sarkissian
- CBRC, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA
| | - Y Tan
- CBRC, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA
| | - K White
- CBRC, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA
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123
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Newbern JM. Molecular control of the neural crest and peripheral nervous system development. Curr Top Dev Biol 2015; 111:201-31. [PMID: 25662262 DOI: 10.1016/bs.ctdb.2014.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A transient and unique population of multipotent stem cells, known as neural crest cells (NCCs), generate a bewildering array of cell types during vertebrate development. An attractive model among developmental biologists, the study of NCC biology has provided a wealth of knowledge regarding the cellular and molecular mechanisms important for embryogenesis. Studies in numerous species have defined how distinct phases of NCC specification, proliferation, migration, and survival contribute to the formation of multiple functionally distinct organ systems. NCC contributions to the peripheral nervous system (PNS) are well known. Critical developmental processes have been defined that provide outstanding models for understanding how extracellular stimuli, cell-cell interactions, and transcriptional networks cooperate to direct cellular diversification and PNS morphogenesis. Dissecting the complex extracellular and intracellular mechanisms that mediate the formation of the PNS from NCCs may have important therapeutic implications for neurocristopathies, neuropathies, and certain forms of cancer.
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Affiliation(s)
- Jason M Newbern
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA.
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125
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Imbeault E, Mahvelati TM, Braun R, Gris P, Gris D. Nlrx1 regulates neuronal cell death. Mol Brain 2014; 7:90. [PMID: 25540124 PMCID: PMC4302421 DOI: 10.1186/s13041-014-0090-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 12/14/2014] [Indexed: 12/20/2022] Open
Abstract
Background Regulation of cell death during neurodegeneration is one of the key factors that play a role in the speed at which a disease progresses. Out of several cellular pathways responsible for this progression, necrosis and apoptosis are situated on the opposite spectrum of cell death regulation. Necrosis produces an environment that promotes inflammation and cytotoxicity and apoptosis is a highly organized process that maintains tissue homeostasis. A recently discovered protein, Nlrx1, regulates inflammatory and cell death responses during infection. Findings Using transfections of N2A cell line, we demonstrate that Nlrx1 redirects cells away from necrosis and towards an apoptotic pathway following rotenone treatments. In addition, Nlrx1 promotes DRP1 phosphorylation and increases mitochondrial fission. Conclusion Our results suggest a novel molecular pathway for regulating mitochondrial dynamics and neuronal death. Nlrx1 may play an important role in neurodegenerative diseases, where necrosis is a prominent factor.
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Affiliation(s)
- Emilie Imbeault
- Program of Immunology, Department of Paediatrics, CR-CHUS, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada.
| | - Tara M Mahvelati
- Program of Immunology, Department of Paediatrics, CR-CHUS, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada.
| | - Ralf Braun
- Institut fuer Zellbiologie, Universitaet Bayreuth, Bayreuth, Germany.
| | - Pavel Gris
- Montreal Neurological Institute, McGill University, Montréal, QC, Canada.
| | - Denis Gris
- Program of Immunology, Department of Paediatrics, CR-CHUS, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada.
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Narasimhan M, Riar AK, Rathinam ML, Vedpathak D, Henderson G, Mahimainathan L. Hydrogen peroxide responsive miR153 targets Nrf2/ARE cytoprotection in paraquat induced dopaminergic neurotoxicity. Toxicol Lett 2014; 228:179-91. [PMID: 24866057 PMCID: PMC4122323 DOI: 10.1016/j.toxlet.2014.05.020] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 12/11/2022]
Abstract
Epidemiological and animal studies suggest that environmental toxins including paraquat (PQ) increase the risk of developing Parkinson's disease (PD) by damaging nigrostriatal dopaminergic neurons. We previously showed that overexpression of a group of microRNAs (miRs) affects the antioxidant promoting factor, Nrf2 and related glutathione-redox homeostasis in SH-SY5Y dopaminergic neurons. Although, dysregulation of redox balance by PQ is well documented, the role for miRs and their impact have not been elucidated. In the current study we investigated whether PQ impairs Nrf2 and its related cytoprotective machinery by misexpression of specific fine tune miRs in SH-SY5Y neurons. Real time PCR analysis revealed that PQ significantly (p<0.05) increased the expression of brain enriched miR153 with an associated decrease in Nrf2 and its function as revealed by decrease in 4× ARE activity and expression of GCLC and NQO1. Also, PQ and H2O2-induced decrease in Nrf2 3' UTR activity was restored on miR153 site mutation suggesting a 3' UTR interacting role. Overexpression of either anti-miR153 or Nrf2 cDNA devoid of 3' UTR prevented PQ and H2O2-induced loss in Nrf2 activity confirming that PQ could cause miR153 to bind to and target Nrf2 3' UTR thereby weakening the cellular antioxidant defense. Adenovirus mediated overexpression of cytoplasmic catalase (Ad cCAT) confirmed that PQ induced miR153 is hydrogen peroxide (H2O2) dependent. In addition, Ad cCAT significantly (p<0.05) negated the PQ induced dysregulation of Nrf2 and function along with minimizing ROS, caspase 3/7 activation and neuronal death. Altogether, these results suggest a critical role for oxidant mediated miR153-Nrf2/ARE pathway interaction in paraquat neurotoxicity. This novel finding facilitates the understanding of molecular mechanisms and to develop appropriate management alternatives to counteract PQ-induced neuronal pathogenesis.
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Affiliation(s)
- Madhusudhanan Narasimhan
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430 USA; South Plains Alcohol and Addiction Research Center, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
| | - Amanjot Kaur Riar
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430 USA
| | - Mary Latha Rathinam
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430 USA
| | - Dhanashree Vedpathak
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430 USA
| | - George Henderson
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430 USA; South Plains Alcohol and Addiction Research Center, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Lenin Mahimainathan
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430 USA; South Plains Alcohol and Addiction Research Center, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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Innate immune responses regulate morphogenesis and degeneration: roles of Toll-like receptors and Sarm1 in neurons. Neurosci Bull 2014; 30:645-54. [PMID: 24993772 DOI: 10.1007/s12264-014-1445-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 04/28/2014] [Indexed: 10/25/2022] Open
Abstract
The central nervous system is recognized as an immunoprivileged site because peripheral immune cells do not typically enter it. Microglial cells are thought to be the main immune cells in brain. However, recent reports have indicated that neurons express the key players of innate immunity, including Toll-like receptors (TLRs) and their adaptor proteins (Sarm1, Myd88, and Trif), and may produce cytokines in response to pathogen infection. In the absence of an immune challenge, neuronal TLRs can detect intrinsic danger signals and modulate neuronal morphology and function. In this article, we review the recent findings on the involvement of TLRs and Sarm1 in controlling neuronal morphogenesis and neurodegeneration. Abnormal behaviors in TLR- and Sarm1-deficient mice are also discussed.
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128
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Thauerer B, Voegele P, Hermann-Kleiter N, Thuille N, de Araujo MEG, Offterdinger M, Baier G, Huber LA, Baier-Bitterlich G. LAMTOR2-mediated modulation of NGF/MAPK activation kinetics during differentiation of PC12 cells. PLoS One 2014; 9:e95863. [PMID: 24752675 PMCID: PMC3994133 DOI: 10.1371/journal.pone.0095863] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 03/31/2014] [Indexed: 12/26/2022] Open
Abstract
LAMTOR2 (p14), a part of the larger LAMTOR/Ragulator complex, plays a crucial role in EGF-dependent activation of p42/44 mitogen-activated protein kinases (MAPK, ERK1/2). In this study, we investigated the role of LAMTOR2 in nerve growth factor (NGF)-mediated neuronal differentiation. Stimulation of PC12 (rat adrenal pheochromocytoma) cells with NGF is known to activate the MAPK. Pharmacological inhibition of MEK1 as well as siRNA–mediated knockdown of both p42 and p44 MAPK resulted in inhibition of neurite outgrowth. Contrary to expectations, siRNA–mediated knockdown of LAMTOR2 effectively augmented neurite formation and neurite length of PC12 cells. Ectopic expression of a siRNA-resistant LAMTOR2 ortholog reversed this phenotype back to wildtype levels, ruling out nonspecific off-target effects of this LAMTOR2 siRNA approach. Mechanistically, LAMTOR2 siRNA treatment significantly enhanced NGF-dependent MAPK activity, and this effect again was reversed upon expression of the siRNA-resistant LAMTOR2 ortholog. Studies of intracellular trafficking of the NGF receptor TrkA revealed a rapid colocalization with early endosomes, which was modulated by LAMTOR2 siRNA. Inhibition of LAMTOR2 and concomitant destabilization of the remaining members of the LAMTOR complex apparently leads to a faster release of the TrkA/MAPK signaling module and nuclear increase of activated MAPK. These results suggest a modulatory role of the MEK1 adapter protein LAMTOR2 in NGF-mediated MAPK activation required for induction of neurite outgrowth in PC12 cells.
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Affiliation(s)
- Bettina Thauerer
- Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Paul Voegele
- Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria
- Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Natascha Hermann-Kleiter
- Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Nikolaus Thuille
- Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Mariana E. G. de Araujo
- Division of Cell Biology, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Offterdinger
- Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Gottfried Baier
- Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Lukas A. Huber
- Division of Cell Biology, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Gabriele Baier-Bitterlich
- Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria
- * E-mail:
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Corty MM, Freeman MR. Cell biology in neuroscience: Architects in neural circuit design: glia control neuron numbers and connectivity. ACTA ACUST UNITED AC 2014; 203:395-405. [PMID: 24217617 PMCID: PMC3824021 DOI: 10.1083/jcb.201306099] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Glia serve many important functions in the mature nervous system. In addition, these diverse cells have emerged as essential participants in nearly all aspects of neural development. Improved techniques to study neurons in the absence of glia, and to visualize and manipulate glia in vivo, have greatly expanded our knowledge of glial biology and neuron-glia interactions during development. Exciting studies in the last decade have begun to identify the cellular and molecular mechanisms by which glia exert control over neuronal circuit formation. Recent findings illustrate the importance of glial cells in shaping the nervous system by controlling the number and connectivity of neurons.
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Affiliation(s)
- Megan M Corty
- Department of Neurobiology, University of Massachusetts Medical School, Howard Hughes Medical Institute, Worcester, MA 01605
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