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Soto-Verdugo J, Siva-Parra J, Hernández-Kelly LC, Ortega A. Acute Manganese Exposure Modifies the Translation Machinery via PI3K/Akt Signaling in Glial Cells. ASN Neuro 2022; 14:17590914221131452. [PMID: 36203371 PMCID: PMC9551334 DOI: 10.1177/17590914221131452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SUMMARY STATEMENT We demonstrate herein that short-term exposure of radial glia cells to Manganese, a neurotoxic metal, induces an effect on protein synthesis, altering the protein repertoire of these cells.
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Affiliation(s)
| | | | | | - Arturo Ortega
- Arturo Ortega, Departamento de Toxicología,
Centro de Investigación y de Estudios Avanzados del Instituto Politécnico
Nacional, México City, México, 07360.
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2
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Purushotham SS, Reddy NMN, D'Souza MN, Choudhury NR, Ganguly A, Gopalakrishna N, Muddashetty R, Clement JP. A perspective on molecular signalling dysfunction, its clinical relevance and therapeutics in autism spectrum disorder. Exp Brain Res 2022; 240:2525-2567. [PMID: 36063192 DOI: 10.1007/s00221-022-06448-x] [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: 06/01/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022]
Abstract
Intellectual disability (ID) and autism spectrum disorder (ASD) are neurodevelopmental disorders that have become a primary clinical and social concern, with a prevalence of 2-3% in the population. Neuronal function and behaviour undergo significant malleability during the critical period of development that is found to be impaired in ID/ASD. Human genome sequencing studies have revealed many genetic variations associated with ASD/ID that are further verified by many approaches, including many mouse and other models. These models have facilitated the identification of fundamental mechanisms underlying the pathogenesis of ASD/ID, and several studies have proposed converging molecular pathways in ASD/ID. However, linking the mechanisms of the pathogenic genes and their molecular characteristics that lead to ID/ASD has progressed slowly, hampering the development of potential therapeutic strategies. This review discusses the possibility of recognising the common molecular causes for most ASD/ID based on studies from the available models that may enable a better therapeutic strategy to treat ID/ASD. We also reviewed the potential biomarkers to detect ASD/ID at early stages that may aid in diagnosis and initiating medical treatment, the concerns with drug failure in clinical trials, and developing therapeutic strategies that can be applied beyond a particular mutation associated with ASD/ID.
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Affiliation(s)
- Sushmitha S Purushotham
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Neeharika M N Reddy
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Michelle Ninochka D'Souza
- Centre for Brain Research, Indian Institute of Science Campus, CV Raman Avenue, Bangalore, 560 012, India.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India
| | - Nilpawan Roy Choudhury
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Anusa Ganguly
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Niharika Gopalakrishna
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Ravi Muddashetty
- Centre for Brain Research, Indian Institute of Science Campus, CV Raman Avenue, Bangalore, 560 012, India.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India
| | - James P Clement
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India.
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3
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Fu R, Gillen AE, Grabek KR, Riemondy KA, Epperson LE, Bustamante CD, Hesselberth JR, Martin SL. Dynamic RNA Regulation in the Brain Underlies Physiological Plasticity in a Hibernating Mammal. Front Physiol 2021; 11:624677. [PMID: 33536943 PMCID: PMC7848201 DOI: 10.3389/fphys.2020.624677] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 12/29/2020] [Indexed: 12/13/2022] Open
Abstract
Hibernation is a physiological and behavioral phenotype that minimizes energy expenditure. Hibernators cycle between profound depression and rapid hyperactivation of multiple physiological processes, challenging our concept of mammalian homeostasis. How the hibernator orchestrates and survives these extremes while maintaining cell to organismal viability is unknown. Here, we enhance the genome integrity and annotation of a model hibernator, the 13-lined ground squirrel. Our new assembly brings this genome to near chromosome-level contiguity and adds thousands of previously unannotated genes. These new genomic resources were used to identify 6,505 hibernation-related, differentially-expressed and processed transcripts using RNA-seq data from three brain regions in animals whose physiological status was precisely defined using body temperature telemetry. A software tool, squirrelBox, was developed to foster further data analyses and visualization. SquirrelBox includes a comprehensive toolset for rapid visualization of gene level and cluster group dynamics, sequence scanning of k-mer and domains, and interactive exploration of gene lists. Using these new tools and data, we deconvolute seasonal from temperature-dependent effects on the brain transcriptome during hibernation for the first time, highlighting the importance of carefully timed samples for studies of differential gene expression in hibernation. The identified genes include a regulatory network of RNA binding proteins that are dynamic in hibernation along with the composition of the RNA pool. In addition to passive effects of temperature, we provide evidence for regulated transcription and RNA turnover during hibernation. Significant alternative splicing, largely temperature dependent, also occurs during hibernation. These findings form a crucial first step and provide a roadmap for future work toward defining novel mechanisms of tissue protection and metabolic depression that may 1 day be applied toward improving human health.
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Affiliation(s)
- Rui Fu
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, United States
| | - Austin E Gillen
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, United States
| | - Katharine R Grabek
- Fauna Bio Incorporated, Emeryville, CA, United States.,Department of Biomedical Data Science, Stanford University, Stanford, CA, United States
| | - Kent A Riemondy
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, United States
| | - L Elaine Epperson
- Center for Genes, Environment & Health, National Jewish Health, Denver, CO, United States
| | - Carlos D Bustamante
- Department of Biomedical Data Science, Stanford University, Stanford, CA, United States
| | - Jay R Hesselberth
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Sandra L Martin
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Cell & Developmental Biology, School of Medicine, University of Colorado, Aurora, CO, United States
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4
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David O, Barrera I, Gould N, Gal-Ben-Ari S, Rosenblum K. D1 Dopamine Receptor Activation Induces Neuronal eEF2 Pathway-Dependent Protein Synthesis. Front Mol Neurosci 2020; 13:67. [PMID: 32499677 PMCID: PMC7242790 DOI: 10.3389/fnmol.2020.00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/07/2020] [Indexed: 12/31/2022] Open
Abstract
Dopamine, alongside other neuromodulators, defines brain and neuronal states, inter alia through regulation of global and local mRNA translation. Yet, the signaling pathways underlying the effects of dopamine on mRNA translation and psychiatric disorders are not clear. In order to examine the molecular pathways downstream of dopamine receptors, we used genetic, pharmacologic, biochemical, and imaging methods, and found that activation of dopamine receptor D1 but not D2 leads to rapid dephosphorylation of eEF2 at Thr56 but not eIF2α in cortical primary neuronal culture in a time-dependent manner. NMDA receptor, mTOR, and ERK pathways are upstream of the D1 receptor-dependent eEF2 dephosphorylation and essential for it. Furthermore, D1 receptor activation resulted in a major reduction in dendritic eEF2 phosphorylation levels. D1-dependent eEF2 dephosphorylation results in an increase of BDNF and synapsin2b expression which was followed by a small yet significant increase in general protein synthesis. These results reveal the role of dopamine D1 receptor in the regulation of eEF2 pathway translation in neurons and present eEF2 as a promising therapeutic target for addiction and depression as well as other psychiatric disorders.
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Affiliation(s)
- Orit David
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Iliana Barrera
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel.,School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Nathaniel Gould
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | | | - Kobi Rosenblum
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel.,Center for Gene Manipulation in the Brain, University of Haifa, Haifa, Israel
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5
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Madan JS, Gupta K, Chattarji S, Bhattacharya A. Hippocampal and amygdalar cell-specific translation is similar soon after stress but diverge over time. Hippocampus 2019; 28:441-452. [PMID: 29626848 DOI: 10.1002/hipo.22845] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 03/16/2018] [Accepted: 03/26/2018] [Indexed: 01/16/2023]
Abstract
Stress is known to cause contrasting patterns of morphological and physiological plasticity in the hippocampus and amygdala. An obligatory cellular process underlying such neural changes is de novo translation and alterations in protein expression. Yet the nature of the translational response to stress in neurons remains largely unexplored. Even less is known about how glia are affected. Using a click-chemistry-based method to label the de novo proteome in live brain slices, we monitored translation in neurons and astrocytes of the basolateral amygdala (BLA) and dorsal hippocampal area CA3 (dCA3) in rats at different time-points after a single 2-hr exposure to immobilization stress. We observed enhancements in neuronal translation in both brain regions 1 hour after stress. This initial increase persisted in the BLA up to 10 days afterwards. In contrast, dCA3 neuronal translation gradually decreased to below control levels 10 days later. Translation profiles of dCA3 astrocytes followed timelines similar to neurons, but in BLA astrocytes translation peaked 1 day later and remained elevated 10 days later. Together our results demonstrate that stress causes an immediate upregulation of protein synthesis in both amygdalar and hippocampal neurons and astrocytes. However, these two areas eventually exhibit opposite temporal profiles of protein expression well after the end of stress. These findings identify new metrics of stress-induced plasticity at the level of cell-type specific proteomic landscape that may provide important insights into the molecular basis of the divergent temporal effects of stress across brain regions and biological scales.
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Affiliation(s)
- Jesvin S Madan
- National Centre for Biological Sciences, Tata Institute for Fundamental Research, Bangalore, 560065, India
| | - Kanika Gupta
- National Centre for Biological Sciences, Tata Institute for Fundamental Research, Bangalore, 560065, India
| | - Sumantra Chattarji
- National Centre for Biological Sciences, Tata Institute for Fundamental Research, Bangalore, 560065, India.,Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore, 560065, India.,Center for Integrative Physiology, Deanery of Biomedical Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH89XD, United Kingdom
| | - Aditi Bhattacharya
- Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore, 560065, India
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6
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Bowling HL, Nayak S, Deinhardt K. Proteomic Approaches to Dissect Neuronal Signalling Pathways. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1140:469-475. [PMID: 31347065 DOI: 10.1007/978-3-030-15950-4_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
With an increasing awareness of mental health issues and neurological disorders, "understanding the brain" is one of the biggest current challenges in biological research. This has been recognised by both governments and funding agencies, and it includes the need to understand connectivity of brain regions and coordinated network activity, as well as cellular and molecular mechanisms at play. In this chapter, we will describe how we have taken advantage of different proteomic techniques to unravel molecular mechanisms underlying two modulators of neuronal function: Neurotrophins and antipsychotics.
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Affiliation(s)
| | - Shruti Nayak
- Proteomics Laboratory, Alexandria Center for Life Science, NYU Langone, New York, NY, USA
| | - Katrin Deinhardt
- Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK.
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7
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Schmitz F, Chao MV, Wyse ATS. Methylphenidate alters Akt-mTOR signaling in rat pheochromocytoma cells. Int J Dev Neurosci 2018; 73:10-18. [PMID: 30578823 DOI: 10.1016/j.ijdevneu.2018.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/13/2018] [Accepted: 12/17/2018] [Indexed: 12/12/2022] Open
Abstract
The exponential increase in methylphenidate (MPH) prescriptions in recent years has worried researchers about its misuse among individuals who do not meet the full diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD) such as young children and students in search of cognitive improvement or for recreational reasons. The action of MPH is based mainly on inhibition of dopamine transporter, but the complete cellular effects are still unknown. Based upon prior studies, we attempted to determine whether the treatment with MPH (1μM) influences protein kinase B-mammalian target of rapamycin complex 1 signaling pathways (Akt-mTOR), including translation repressor protein (4E-BP1) and mitogen activated protein kinase (S6K), in rat pheochromocytoma cells (PC12), a well characterized cellular model, in a long or short term. MPH effects on the Akt substrates [cAMP response element-binding protein (CREB), forkhead box protein O1 (FoxO1), and glycogen synthase kinase 3 beta (GSK-3β)] were also evaluated. Whereas short term MPH treatment decreased the pAkt/Akt, pmTOR/mTOR and pS6K/S6K ratios, as well as pFoxO1 immunocontent in PC12 cells, long term treatment increased pAkt/Akt, pmTOR/mTOR and pGSK-3β/GSK-3β ratio. Phosphorylation levels of 4E-BP1 were decreased at 15 and 30 min and increased at 1 and 6 h by MPH. pCREB/CREB ratio was decreased. This study shows that the Akt-mTOR pathway, as well as other important Akt substrates which have been described as important regulators of protein synthesis, as well as being implicated in cellular survival, synaptic plasticity and memory consolidation, was affected by MPH in PC12 cells, representing an important step in exploring the MPH effects.
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Affiliation(s)
- Felipe Schmitz
- Departments of Cell Biology, Physiology & Neuroscience, and Psychiatry, Skirball Institute of Biomolecular Medicine, New York University, New York, NY, USA; Laboratory of Neuroprotection and Metabolic Diseases, Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
| | - Moses V Chao
- Departments of Cell Biology, Physiology & Neuroscience, and Psychiatry, Skirball Institute of Biomolecular Medicine, New York University, New York, NY, USA
| | - Angela T S Wyse
- Laboratory of Neuroprotection and Metabolic Diseases, Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Programa de Pós‑Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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8
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George G, Singh S, Lokappa SB, Varkey J. Gene co-expression network analysis for identifying genetic markers in Parkinson's disease - a three-way comparative approach. Genomics 2018; 111:819-830. [PMID: 29852216 DOI: 10.1016/j.ygeno.2018.05.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 04/16/2018] [Accepted: 05/06/2018] [Indexed: 12/30/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder involving progressive deterioration of dopaminergic neurons. Although few genetic markers for familial PD are known, the etiology of sporadic PD remains poorly understood. Microarray data was analysed for induced pluripotent stem cells (iPSCs) derived from PD patients and mature neuronal cells (mDA) differentiated from these iPSCs. Combining expression and semantic similarity, a highly-correlated PD interactome was constructed that included interactions of established Parkinson's disease marker genes. A novel three-way comparative approach was employed, delineating topologically and functionally important genes. These genes showed involvement in pathways like Parkin-ubiquitin proteosomal system (UPS), immune associated biological processes and apoptosis. Of interest are three genes, eEF1A1, CASK, and PSMD6 that are linked to PARK2 activity in the cell and thereby form attractive candidate genes for understanding PD. Network biology approach delineated in this study can be applied to other neurodegenerative disorders for identification of important genetic regulators.
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Affiliation(s)
- Gincy George
- Department of Bioinformatics, Karunya University, Karunya Nagar, Tamil Nadu 641114, India
| | - Sachidanand Singh
- Department of Bioinformatics, Karunya University, Karunya Nagar, Tamil Nadu 641114, India; Institute of Bio-Sciences and Technology, Shri Ramswaroop Memorial University, Deva Road, Uttar Pradesh 225003, India
| | - Sowmya Bekshe Lokappa
- Department of Bioinformatics, Karunya University, Karunya Nagar, Tamil Nadu 641114, India; Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, USA.
| | - Jobin Varkey
- Department of Bioinformatics, Karunya University, Karunya Nagar, Tamil Nadu 641114, India; Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, USA.
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9
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Niere F, Raab-Graham KF. mTORC1 Is a Local, Postsynaptic Voltage Sensor Regulated by Positive and Negative Feedback Pathways. Front Cell Neurosci 2017; 11:152. [PMID: 28611595 PMCID: PMC5447718 DOI: 10.3389/fncel.2017.00152] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/09/2017] [Indexed: 12/11/2022] Open
Abstract
The mammalian/mechanistic target of rapamycin complex 1 (mTORC1) serves as a regulator of mRNA translation. Recent studies suggest that mTORC1 may also serve as a local, voltage sensor in the postsynaptic region of neurons. Considering biochemical, bioinformatics and imaging data, we hypothesize that the activity state of mTORC1 dynamically regulates local membrane potential by promoting and repressing protein synthesis of select mRNAs. Our hypothesis suggests that mTORC1 uses positive and negative feedback pathways, in a branch-specific manner, to maintain neuronal excitability within an optimal range. In some dendritic branches, mTORC1 activity oscillates between the "On" and "Off" states. We define this as negative feedback. In contrast, positive feedback is defined as the pathway that leads to a prolonged depolarized or hyperpolarized resting membrane potential, whereby mTORC1 activity is constitutively on or off, respectively. We propose that inactivation of mTORC1 increases the expression of voltage-gated potassium alpha (Kv1.1 and 1.2) and beta (Kvβ2) subunits, ensuring that the membrane resets to its resting membrane potential after experiencing increased synaptic activity. In turn, reduced mTORC1 activity increases the protein expression of syntaxin-1A and promotes the surface expression of the ionotropic glutamate receptor N-methyl-D-aspartate (NMDA)-type subunit 1 (GluN1) that facilitates increased calcium entry to turn mTORC1 back on. Under conditions such as learning and memory, mTORC1 activity is required to be high for longer periods of time. Thus, the arm of the pathway that promotes syntaxin-1A and Kv1 protein synthesis will be repressed. Moreover, dendritic branches that have low mTORC1 activity with increased Kv expression would balance dendrites with constitutively high mTORC1 activity, allowing for the neuron to maintain its overall activity level within an ideal operating range. Finally, such a model suggests that recruitment of more positive feedback dendritic branches within a neuron is likely to lead to neurodegenerative disorders.
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Affiliation(s)
- Farr Niere
- Department of Physiology and Pharmacology, Wake Forest School of MedicineWinston-Salem, NC, United States
| | - Kimberly F. Raab-Graham
- Department of Physiology and Pharmacology, Wake Forest School of MedicineWinston-Salem, NC, United States
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10
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Chahrour M, O'Roak BJ, Santini E, Samaco RC, Kleiman RJ, Manzini MC. Current Perspectives in Autism Spectrum Disorder: From Genes to Therapy. J Neurosci 2016; 36:11402-11410. [PMID: 27911742 PMCID: PMC5125207 DOI: 10.1523/jneurosci.2335-16.2016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/23/2016] [Accepted: 08/25/2016] [Indexed: 12/17/2022] Open
Abstract
Autism spectrum disorder (ASD) is a constellation of neurodevelopmental presentations with high heritability and both phenotypic and genetic heterogeneity. To date, mutations in hundreds of genes have been associated to varying degrees with increased ASD risk. A better understanding of the functions of these genes and whether they fit together in functional groups or impact similar neuronal circuits is needed to develop rational treatment strategies. We will review current areas of emphasis in ASD research, starting from human genetics and exploring how mouse models of human mutations have helped identify specific molecular pathways (protein synthesis and degradation, chromatin remodeling, intracellular signaling), which are linked to alterations in circuit function and cognitive/social behavior. We will conclude by discussing how we can leverage the findings on molecular and cellular alterations found in ASD to develop therapies for neurodevelopmental disorders.
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Affiliation(s)
- Maria Chahrour
- Eugene McDermott Center for Human Growth and Development, Departments of Neuroscience and Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390,
| | - Brian J O'Roak
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon 97239
| | - Emanuela Santini
- Center for Neural Science, New York University, New York, New York 10003
| | - Rodney C Samaco
- Department of Molecular and Human Genetics, Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Robin J Kleiman
- Translational Neuroscience Center, F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, and
| | - M Chiara Manzini
- Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037
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11
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Raab-Graham KF, Workman ER, Namjoshi S, Niere F. Pushing the threshold: How NMDAR antagonists induce homeostasis through protein synthesis to remedy depression. Brain Res 2016; 1647:94-104. [PMID: 27125595 DOI: 10.1016/j.brainres.2016.04.020] [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: 12/17/2015] [Revised: 04/04/2016] [Accepted: 04/07/2016] [Indexed: 12/17/2022]
Abstract
Healthy neurons have an optimal operating range, coded globally by the frequency of action potentials or locally by calcium. The maintenance of this range is governed by homeostatic plasticity. Here, we discuss how new approaches to treat depression alter synaptic activity. These approaches induce the neuron to recruit homeostatic mechanisms to relieve depression. Homeostasis generally implies that the direction of activity necessary to restore the neuron's critical operating range is opposite in direction to its current activity pattern. Unconventional antidepressant therapies-deep brain stimulation and NMDAR antagonists-alter the neuron's "depressed" state by pushing the neuron's current activity in the same direction but to the extreme edge. These therapies rally the intrinsic drive of neurons in the opposite direction, thereby allowing the cell to return to baseline activity, form new synapses, and restore proper communication. In this review, we discuss seminal studies on protein synthesis dependent homeostatic plasticity and their contribution to our understanding of molecular mechanisms underlying the effectiveness of NMDAR antagonists as rapid antidepressants. Rapid antidepressant efficacy is likely to require a cascade of mRNA translational regulation. Emerging evidence suggests that changes in synaptic strength or intrinsic excitability converge on the same protein synthesis pathways, relieving depressive symptoms. Thus, we address the question: Are there multiple homeostatic mechanisms that induce the neuron and neuronal circuits to self-correct to regulate mood in vivo? Targeting alternative ways to induce homeostatic protein synthesis may provide, faster, safer, and longer lasting antidepressants. This article is part of a Special Issue entitled SI:RNA Metabolism in Disease.
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Affiliation(s)
- Kimberly F Raab-Graham
- Center for Learning and Memory, Department of Neuroscience, Institute of Neuroscience, University of Texas at Austin, Austin, TX 78712, United States; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, United States; Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, United States.
| | - Emily R Workman
- Center for Learning and Memory, Department of Neuroscience, Institute of Neuroscience, University of Texas at Austin, Austin, TX 78712, United States; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, United States
| | - Sanjeev Namjoshi
- Center for Learning and Memory, Department of Neuroscience, Institute of Neuroscience, University of Texas at Austin, Austin, TX 78712, United States; Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, United States
| | - Farr Niere
- Center for Learning and Memory, Department of Neuroscience, Institute of Neuroscience, University of Texas at Austin, Austin, TX 78712, United States; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, United States
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12
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Niere F, Namjoshi S, Song E, Dilly GA, Schoenhard G, Zemelman BV, Mechref Y, Raab-Graham KF. Analysis of Proteins That Rapidly Change Upon Mechanistic/Mammalian Target of Rapamycin Complex 1 (mTORC1) Repression Identifies Parkinson Protein 7 (PARK7) as a Novel Protein Aberrantly Expressed in Tuberous Sclerosis Complex (TSC). Mol Cell Proteomics 2015; 15:426-44. [PMID: 26419955 DOI: 10.1074/mcp.m115.055079] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Indexed: 01/05/2023] Open
Abstract
Many biological processes involve the mechanistic/mammalian target of rapamycin complex 1 (mTORC1). Thus, the challenge of deciphering mTORC1-mediated functions during normal and pathological states in the central nervous system is challenging. Because mTORC1 is at the core of translation, we have investigated mTORC1 function in global and regional protein expression. Activation of mTORC1 has been generally regarded to promote translation. Few but recent works have shown that suppression of mTORC1 can also promote local protein synthesis. Moreover, excessive mTORC1 activation during diseased states represses basal and activity-induced protein synthesis. To determine the role of mTORC1 activation in protein expression, we have used an unbiased, large-scale proteomic approach. We provide evidence that a brief repression of mTORC1 activity in vivo by rapamycin has little effect globally, yet leads to a significant remodeling of synaptic proteins, in particular those proteins that reside in the postsynaptic density. We have also found that curtailing the activity of mTORC1 bidirectionally alters the expression of proteins associated with epilepsy, Alzheimer's disease, and autism spectrum disorder-neurological disorders that exhibit elevated mTORC1 activity. Through a protein-protein interaction network analysis, we have identified common proteins shared among these mTORC1-related diseases. One such protein is Parkinson protein 7, which has been implicated in Parkinson's disease, yet not associated with epilepsy, Alzheimers disease, or autism spectrum disorder. To verify our finding, we provide evidence that the protein expression of Parkinson protein 7, including new protein synthesis, is sensitive to mTORC1 inhibition. Using a mouse model of tuberous sclerosis complex, a disease that displays both epilepsy and autism spectrum disorder phenotypes and has overactive mTORC1 signaling, we show that Parkinson protein 7 protein is elevated in the dendrites and colocalizes with the postsynaptic marker postsynaptic density-95. Our work offers a comprehensive view of mTORC1 and its role in regulating regional protein expression in normal and diseased states.
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Affiliation(s)
- Farr Niere
- From the ‡Center for Learning and Memory, University of Texas, Austin, 1 University Station C7000, Texas 78712; §Institute for Cell and Molecular Biology, University of Texas, Austin, Texas; ¶Institute for Neuroscience, University of Texas, Austin, Texas; ‖Waggoner Center for Alcohol and Addiction Research, University of Texas, Austin, Texas
| | - Sanjeev Namjoshi
- From the ‡Center for Learning and Memory, University of Texas, Austin, 1 University Station C7000, Texas 78712; §Institute for Cell and Molecular Biology, University of Texas, Austin, Texas
| | - Ehwang Song
- **Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409
| | - Geoffrey A Dilly
- From the ‡Center for Learning and Memory, University of Texas, Austin, 1 University Station C7000, Texas 78712; §Institute for Cell and Molecular Biology, University of Texas, Austin, Texas; ¶Institute for Neuroscience, University of Texas, Austin, Texas
| | - Grant Schoenhard
- ‡‡Pain Therapeutics, Inc., 7801 N Capital of Texas Hwy, #260, Austin, Texas 78731
| | - Boris V Zemelman
- From the ‡Center for Learning and Memory, University of Texas, Austin, 1 University Station C7000, Texas 78712; §Institute for Cell and Molecular Biology, University of Texas, Austin, Texas; ¶Institute for Neuroscience, University of Texas, Austin, Texas
| | - Yehia Mechref
- **Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409
| | - Kimberly F Raab-Graham
- From the ‡Center for Learning and Memory, University of Texas, Austin, 1 University Station C7000, Texas 78712; §Institute for Cell and Molecular Biology, University of Texas, Austin, Texas; ¶Institute for Neuroscience, University of Texas, Austin, Texas; ‖Waggoner Center for Alcohol and Addiction Research, University of Texas, Austin, Texas; ‡‡Pain Therapeutics, Inc., 7801 N Capital of Texas Hwy, #260, Austin, Texas 78731
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Angliker N, Burri M, Zaichuk M, Fritschy JM, Rüegg MA. mTORC1 and mTORC2 have largely distinct functions in Purkinje cells. Eur J Neurosci 2015; 42:2595-612. [DOI: 10.1111/ejn.13051] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 08/13/2015] [Accepted: 08/14/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Nico Angliker
- Biozentrum; University of Basel; Klingelbergstrasse 70 CH-4056 Basel Switzerland
| | - Michael Burri
- Biozentrum; University of Basel; Klingelbergstrasse 70 CH-4056 Basel Switzerland
| | - Mariana Zaichuk
- Institute of Pharmacology and Toxicology; University of Zürich; Zürich Switzerland
| | - Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology; University of Zürich; Zürich Switzerland
| | - Markus A. Rüegg
- Biozentrum; University of Basel; Klingelbergstrasse 70 CH-4056 Basel Switzerland
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14
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Fritsch EB, Stegeman JJ, Goldstone JV, Nacci DE, Champlin D, Jayaraman S, Connon RE, Pessah IN. Expression and function of ryanodine receptor related pathways in PCB tolerant Atlantic killifish (Fundulus heteroclitus) from New Bedford Harbor, MA, USA. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 159:156-66. [PMID: 25546006 PMCID: PMC4300256 DOI: 10.1016/j.aquatox.2014.12.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 12/14/2014] [Accepted: 12/17/2014] [Indexed: 05/12/2023]
Abstract
Atlantic killifish (Fundulus heteroclitus) thrive in New Bedford Harbor (NBH), MA, highly contaminated with polychlorinated biphenyls (PCBs). Resident killifish have evolved tolerance to dioxin-like (DL) PCBs, whose toxic effects through the aryl hydrocarbon receptor (AhR) are well studied. In NBH, non-dioxin like PCBs (NDL PCBs), which lack activity toward the AhR, vastly exceed levels of DL congeners yet how killifish counter NDL toxic effects has not been explored. In mammals and fish, NDL PCBs are potent activators of ryanodine receptors (RyR), Ca(2+) release channels necessary for a vast array of physiological processes. In the current study we compared the expression and function of RyR related pathways in NBH killifish with killifish from the reference site at Scorton Creek (SC, MA). Relative to the SC fish, adults from NBH displayed increased levels of skeletal muscle RyR1 protein, and increased levels of FK506-binding protein 12 kDa (FKBP12) an accessory protein essential for NDL PCB-triggered changes in RyR channel function. In accordance with increased RyR1 levels, NBH killifish displayed increased maximal ligand binding, increased maximal response to Ca(2+) activation and increased maximal response to activation by the NDL PCB congener PCB 95. Compared to SC, NBH embryos and larvae had increased levels of mtor and ryr2 transcripts at multiple stages of development, and generations, while levels of serca2 were decreased at 9 days post-fertilization in the F1 and F2 generations. These findings suggest that there are compensatory and heritable changes in RyR mediated Ca(2+) signaling proteins or potential signaling partners in NBH killifish.
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Affiliation(s)
- Erika B Fritsch
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
| | - John J Stegeman
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Jared V Goldstone
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Diane E Nacci
- Atlantic Ecology Division, Office of Research and Development, US Environmental Protection Agency, Narragansett, RI, USA
| | - Denise Champlin
- Atlantic Ecology Division, Office of Research and Development, US Environmental Protection Agency, Narragansett, RI, USA
| | - Saro Jayaraman
- Atlantic Ecology Division, Office of Research and Development, US Environmental Protection Agency, Narragansett, RI, USA
| | - Richard E Connon
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA; The Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, USA
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15
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Nicolini C, Ahn Y, Michalski B, Rho JM, Fahnestock M. Decreased mTOR signaling pathway in human idiopathic autism and in rats exposed to valproic acid. Acta Neuropathol Commun 2015; 3:3. [PMID: 25627160 PMCID: PMC4307681 DOI: 10.1186/s40478-015-0184-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 01/04/2015] [Indexed: 12/20/2022] Open
Abstract
Background The molecular mechanisms underlying autistic behaviors remain to be elucidated. Mutations in genes linked to autism adversely affect molecules regulating dendritic spine formation, function and plasticity, and some increase the mammalian target of rapamycin, mTOR, a regulator of protein synthesis at spines. Here, we investigated whether the Akt/mTOR pathway is disrupted in idiopathic autism and in rats exposed to valproic acid, an animal model exhibiting autistic-like behavior. Methods Components of the mTOR pathway were assayed by Western blotting in postmortem fusiform gyrus samples from 11 subjects with idiopathic autism and 13 controls and in valproic acid versus saline-exposed rat neocortex. Additionally, protein levels of brain-derived neurotrophic factor receptor (TrkB) isoforms and the postsynaptic organizing molecule PSD-95 were measured in autistic versus control subjects. Results Full-length TrkB, PI3K, Akt, phosphorylated and total mTOR, p70S6 kinase, eIF4B and PSD-95 were reduced in autistic versus control fusiform gyrus. Similarly, phosphorylated and total Akt, mTOR and 4E-BP1 and phosphorylated S6 protein were decreased in valproic acid- versus saline-exposed rats. However, no changes in 4E-BP1 or eIF4E were found in autistic brains. Conclusions In contrast to some monogenic disorders with high rates of autism, our data demonstrate down-regulation of the Akt/mTOR pathway, specifically via p70S6K/eIF4B, in idiopathic autism. These findings suggest that disruption of this pathway in either direction is widespread in autism and can have adverse consequences for synaptic function. The use of valproic acid, a histone deacetylase inhibitor, in rats successfully modeled these changes, implicating an epigenetic mechanism in these pathway disruptions.
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16
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Angliker N, Rüegg MA. In vivo evidence for mTORC2-mediated actin cytoskeleton rearrangement in neurons. BIOARCHITECTURE 2015; 3:113-8. [PMID: 24721730 PMCID: PMC4201605 DOI: 10.4161/bioa.26497] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The mammalian target of rapamycin (mTOR) assembles into two distinct multi-protein complexes called mTORC1 and mTORC2. While mTORC1 controls the signaling pathways important for cell growth, the physiological function of mTORC2 is only partially known. Here we comment on recent work on gene-targeted mice lacking mTORC2 in the cerebellum or the hippocampus that provided strong evidence that mTORC2 plays an important role in neuron morphology and synapse function. We discuss that this phenotype might be based on the perturbed regulation of the actin cytoskeleton and the lack of activation of several PKC isoforms. The fact that PKC isoforms and their targets have been implicated in neurological disease including spinocerebellar ataxia and that they have been shown to affect learning and memory, suggests that aberration of mTORC2 signaling might be involved in diseases of the brain.
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17
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Abstract
Protein translation initiation is controlled by levels of eIF2α phosphorylation (p-eIF2α) on Ser51. In addition, increased p-eIF2α levels impair long-term synaptic plasticity and memory consolidation, whereas decreased levels enhance them. Levels of p-eIF2α are determined by four kinases, of which protein kinase RNA-activated (PKR), PKR-like endoplastic reticulum kinase (PERK), and general control nonderepressible 2 are extensively expressed in the mammalian mature brain. Following identification of PERK as the major kinase to determine basal levels of p-eIF2α in primary neuronal cultures, we tested its function as a physiological constraint of memory consolidation in the cortex, the brain structure suggested to store, at least in part, long-term memories in the mammalian brain. To that aim, insular cortex (IC)-dependent positive and negative forms of taste learning were used. Genetic reduction of PERK expression was accomplished by local microinfusion of a lentivirus harboring PERK Short hairpin RNA, and pharmacological inhibition was achieved by local microinfusion of a PERK-specific inhibitor (GSK2606414) to the rat IC. Both genetic reduction of PERK expression and pharmacological inhibition of its activity reduced p-eIF2α levels and enhanced novel taste learning and conditioned taste aversion, but not memory retrieval. Moreover, enhanced extinction was observed together with enhanced associative memory, suggesting increased cortical-dependent behavioral plasticity. The results suggest that, by phosphorylating eIF2α, PERK functions in the cortex as a physiological constraint of memory consolidation, and its downregulation serves as cognitive enhancement.
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18
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Bowling H, Zhang G, Bhattacharya A, Pérez-Cuesta LM, Deinhardt K, Hoeffer CA, Neubert TA, Gan WB, Klann E, Chao MV. Antipsychotics activate mTORC1-dependent translation to enhance neuronal morphological complexity. Sci Signal 2014; 7:ra4. [PMID: 24425786 PMCID: PMC4063438 DOI: 10.1126/scisignal.2004331] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although antipsychotic drugs can reduce psychotic behavior within a few hours, full efficacy is not achieved for several weeks, implying that there may be rapid, short-term changes in neuronal function, which are consolidated into long-lasting changes. We showed that the antipsychotic drug haloperidol, a dopamine receptor type 2 (D₂R) antagonist, stimulated the kinase Akt to activate the mRNA translation pathway mediated by the mammalian target of rapamycin complex 1 (mTORC1). In primary striatal D₂R-positive neurons, haloperidol-mediated activation of mTORC1 resulted in increased phosphorylation of ribosomal protein S6 (S6) and eukaryotic translation initiation factor 4E-binding protein (4E-BP). Proteomic mass spectrometry revealed marked changes in the pattern of protein synthesis after acute exposure of cultured striatal neurons to haloperidol, including increased abundance of cytoskeletal proteins and proteins associated with translation machinery. These proteomic changes coincided with increased morphological complexity of neurons that was diminished by inhibition of downstream effectors of mTORC1, suggesting that mTORC1-dependent translation enhances neuronal complexity in response to haloperidol. In vivo, we observed rapid morphological changes with a concomitant increase in the abundance of cytoskeletal proteins in cortical neurons of haloperidol-injected mice. These results suggest a mechanism for both the acute and long-term actions of antipsychotics.
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Affiliation(s)
- Heather Bowling
- Departments of Cell Biology, Physiology and Neuroscience, Psychiatry
- Department of Neuroscience and Physiology and Neuroscience, NYU Neuroscience Institute, NYU Langone Medical Center, New York, New York 10016
| | - Guoan Zhang
- Biochemistry and Molecular Pharmacology, Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Langone School of Medicine, New York, New York 10016
| | - Aditi Bhattacharya
- Center for Neural Science, New York University, New York, New York 10003
| | | | - Katrin Deinhardt
- Departments of Cell Biology, Physiology and Neuroscience, Psychiatry
| | - Charles A. Hoeffer
- Department of Neuroscience and Physiology and Neuroscience, NYU Neuroscience Institute, NYU Langone Medical Center, New York, New York 10016
| | - Thomas A. Neubert
- Biochemistry and Molecular Pharmacology, Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Langone School of Medicine, New York, New York 10016
| | - Wen-biao Gan
- Departments of Cell Biology, Physiology and Neuroscience, Psychiatry
- Department of Neuroscience and Physiology and Neuroscience, NYU Neuroscience Institute, NYU Langone Medical Center, New York, New York 10016
| | - Eric Klann
- Center for Neural Science, New York University, New York, New York 10003
| | - Moses V. Chao
- Departments of Cell Biology, Physiology and Neuroscience, Psychiatry
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19
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Bowling HL, Deinhardt K. Proteomic approaches to dissect neuronal signaling pathways. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 806:499-508. [PMID: 24952199 DOI: 10.1007/978-3-319-06068-2_24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
With an increasing awareness of mental health issues and neurological disorders, "understanding the brain" is one of the biggest current challenges in biological research. This has been recognized by both governments and funding agencies, and includes the need to understand connectivity of brain regions and coordinated network activity, as well as cellular and molecular mechanisms at play. In this chapter, we will describe how we have taken advantage of different proteomic techniques to unravel molecular mechanisms underlying two modulators of neuronal function: Neurotrophins and antipsychotics.
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Affiliation(s)
- Heather L Bowling
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA,
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20
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Goodchild RE, Grundmann K, Pisani A. New genetic insights highlight 'old' ideas on motor dysfunction in dystonia. Trends Neurosci 2013; 36:717-25. [PMID: 24144882 DOI: 10.1016/j.tins.2013.09.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 09/12/2013] [Accepted: 09/13/2013] [Indexed: 12/13/2022]
Abstract
Primary dystonia is a poorly understood but common movement disorder. Recently, several new primary dystonia genes were identified that provide new insight into dystonia pathogenesis. The GNAL dystonia gene is central for striatal responses to dopamine (DA) and is a component of a molecular pathway already implicated in DOPA-responsive dystonia (DRD). Furthermore, this pathway is also dysfunctional and pathogenically linked to mTOR signaling in L-DOPA-induced dyskinesias (LID). These new data suggest that striatal DA responses are central to primary dystonia, even when symptoms do not benefit from DA therapies. Here we integrate these new findings with current understanding of striatal microcircuitry and other dystonia-causing insults to develop new ideas on the pathophysiology of this incapacitating movement disorder.
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Affiliation(s)
- Rose E Goodchild
- Vlaams Instituut voor Biotechnologie (VIB) Centre for the Biology of Disease and KU Leuven, Department of Human Genetics, Campus Gasthuisberg, 3000 Leuven, Belgium
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Hartman NW, Lin TV, Zhang L, Paquelet GE, Feliciano DM, Bordey A. mTORC1 targets the translational repressor 4E-BP2, but not S6 kinase 1/2, to regulate neural stem cell self-renewal in vivo. Cell Rep 2013; 5:433-44. [PMID: 24139800 DOI: 10.1016/j.celrep.2013.09.017] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 08/14/2013] [Accepted: 09/11/2013] [Indexed: 12/21/2022] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) integrates signals important for cell growth, and its dysregulation in neural stem cells (NSCs) is implicated in several neurological disorders associated with abnormal neurogenesis and brain size. However, the function of mTORC1 on NSC self-renewal and the downstream regulatory mechanisms are ill defined. Here, we found that genetically decreasing mTORC1 activity in neonatal NSCs prevented their differentiation, resulting in reduced lineage expansion and aborted neuron production. Constitutive activation of the translational repressor 4E-BP1, which blocked cap-dependent translation, had similar effects and prevented hyperactive mTORC1 induction of NSC differentiation and promoted self-renewal. Although 4E-BP2 knockdown promoted NSC differentiation, p70 S6 kinase 1 and 2 (S6K1/S6K2) knockdown did not affect NSC differentiation but reduced NSC soma size and prevented hyperactive mTORC1-induced increase in soma size. These data demonstrate a crucial role of mTORC1 and 4E-BP for switching on and off cap-dependent translation in NSC differentiation.
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Affiliation(s)
- Nathaniel W Hartman
- Departments of Neurosurgery, and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA
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Tolino M, Köhrmann M, Kiebler MA. RNA-binding proteins involved in RNA localization and their implications in neuronal diseases. Eur J Neurosci 2012; 35:1818-36. [PMID: 22708593 DOI: 10.1111/j.1460-9568.2012.08160.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Very often, developmental abnormalities or subtle disturbances of neuronal function may yield brain diseases even if they become obvious only late in life. It is therefore our intention to highlight fundamental mechanisms of neuronal cell biology with a special emphasis on dendritic mRNA localization including local protein synthesis at the activated synapse. Furthermore, we would like to point out possible links to neuronal or synaptic dysfunction. In particular, we will focus on a series of well-known RNA-binding proteins that are involved in these processes and outline how their dysfunction might yield neurodevelopmental, neurodegenerative or neuropsychiatric disorders. We are convinced that increasing our understanding of RNA biology in general and the mechanisms underlying mRNA transport and subsequent translation at the synapse will ultimately generate important novel RNA-based tools in the near future that will allow us to hopefully treat some of these devastating diseases.
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Affiliation(s)
- Marco Tolino
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
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23
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Fisone G, Brambilla R. Neuronal signaling and behavior. Front Behav Neurosci 2012; 6:72. [PMID: 23129996 PMCID: PMC3487157 DOI: 10.3389/fnbeh.2012.00072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 10/16/2012] [Indexed: 11/13/2022] Open
Affiliation(s)
- Gilberto Fisone
- Department of Neuroscience, Karolinska Institutet Stockholm, Sweden
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Trinh MA, Kaphzan H, Wek RC, Pierre P, Cavener DR, Klann E. Brain-specific disruption of the eIF2α kinase PERK decreases ATF4 expression and impairs behavioral flexibility. Cell Rep 2012; 1:676-88. [PMID: 22813743 DOI: 10.1016/j.celrep.2012.04.010] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/16/2012] [Accepted: 04/23/2012] [Indexed: 02/03/2023] Open
Abstract
Translational control depends on phosphorylation of eIF2α by PKR-like ER kinase (PERK). To examine the role of PERK in cognitive function, we selectively disrupted PERK expression in the adult mouse forebrain. In the prefrontal cortex (PFC) of PERK-deficient mice, eIF2α phosphorylation and ATF4 expression were diminished and were associated with enhanced behavioral perseveration, decreased prepulse inhibition, reduced fear extinction, and impaired behavioral flexibility. Treatment with the glycine transporter inhibitor SSR504734 normalized eIF2α phosphorylation, ATF4 expression, and behavioral flexibility in PERK-deficient mice. Moreover, the expression levels of PERK and ATF4 were reduced in the frontal cortex of human patients with schizophrenia. Together, our findings reveal that PERK plays a critical role in information processing and cognitive function and that modulation of eIF2α phosphorylation and ATF4 expression may represent an effective strategy for treating behavioral inflexibility associated with several neurological disorders such as schizophrenia.
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Affiliation(s)
- Mimi A Trinh
- Center for Neural Science, New York University, New York, NY 10003, USA
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Deregulated mTOR-mediated translation in intellectual disability. Prog Neurobiol 2012; 96:268-82. [DOI: 10.1016/j.pneurobio.2012.01.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 01/02/2012] [Accepted: 01/12/2012] [Indexed: 02/04/2023]
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