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Zhang H, Ben Zablah Y, Zhang H, Jia Z. Rho Signaling in Synaptic Plasticity, Memory, and Brain Disorders. Front Cell Dev Biol 2021; 9:729076. [PMID: 34671600 PMCID: PMC8520953 DOI: 10.3389/fcell.2021.729076] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/03/2021] [Indexed: 12/12/2022] Open
Abstract
Memory impairments are associated with many brain disorders such as autism, Alzheimer's disease, and depression. Forming memories involves modifications of synaptic transmission and spine morphology. The Rho family small GTPases are key regulators of synaptic plasticity by affecting various downstream molecules to remodel the actin cytoskeleton. In this paper, we will review recent studies on the roles of Rho proteins in the regulation of hippocampal long-term potentiation (LTP) and long-term depression (LTD), the most extensively studied forms of synaptic plasticity widely regarded as cellular mechanisms for learning and memory. We will also discuss the involvement of Rho signaling in spine morphology, the structural basis of synaptic plasticity and memory formation. Finally, we will review the association between brain disorders and abnormalities of Rho function. It is expected that studying Rho signaling at the synapse will contribute to the understanding of how memory is formed and disrupted in diseases.
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Affiliation(s)
- Haorui Zhang
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Youssif Ben Zablah
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Haiwang Zhang
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Zhengping Jia
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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2
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Zamanian Azodi M, Rezaei Tavirani M, Rezaei Tavirani M, Rostami Nejad M. Bioinformatics Investigation and Contribution of Other Chromosomes Besides Chromosome 21 in the Risk of Down Syndrome Development. Basic Clin Neurosci 2021; 12:79-88. [PMID: 33995930 PMCID: PMC8114864 DOI: 10.32598/bcn.12.1.941.6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 12/24/2018] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION Down syndrome as a genetic disorder is a popular research topic in molecular studies. One way to study Down syndrome is via bioinformatics. METHODS In this study, a gene expression profile from a microarray study was selected for more investigation. RESULTS The study of Down syndrome patients shows specific genes with differential expression and network centrality properties. These genes are introduced as RHOA, FGF2, FYN, and CD44, and their level of expression is high in these patients. CONCLUSION This study suggests that besides chromosomes 21, there are additional contributing chromosomes to the risk of Down syndrome development. Besides, these genes could be used for clinical studies after more analysis.
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Affiliation(s)
- Mona Zamanian Azodi
- Proteomics Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Majid Rezaei Tavirani
- Department of Surgery, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Rostami Nejad
- Research Institute For Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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3
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Khan R, Kulasiri D, Samarasinghe S. Functional repertoire of protein kinases and phosphatases in synaptic plasticity and associated neurological disorders. Neural Regen Res 2021; 16:1150-1157. [PMID: 33269764 PMCID: PMC8224123 DOI: 10.4103/1673-5374.300331] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Protein phosphorylation and dephosphorylation are two essential and vital cellular mechanisms that regulate many receptors and enzymes through kinases and phosphatases. Ca2+- dependent kinases and phosphatases are responsible for controlling neuronal processing; balance is achieved through opposition. During molecular mechanisms of learning and memory, kinases generally modulate positively while phosphatases modulate negatively. This review outlines some of the critical physiological and structural aspects of kinases and phosphatases involved in maintaining postsynaptic structural plasticity. It also explores the link between neuronal disorders and the deregulation of phosphatases and kinases.
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Affiliation(s)
- Raheel Khan
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University; Department of Molecular Biosciences, Lincoln University, Christchurch, New Zealand
| | - Don Kulasiri
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University; Department of Molecular Biosciences, Lincoln University, Christchurch, New Zealand
| | - Sandhya Samarasinghe
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Christchurch, New Zealand
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4
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Ben Zablah Y, Merovitch N, Jia Z. The Role of ADF/Cofilin in Synaptic Physiology and Alzheimer's Disease. Front Cell Dev Biol 2020; 8:594998. [PMID: 33282872 PMCID: PMC7688896 DOI: 10.3389/fcell.2020.594998] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/23/2020] [Indexed: 12/21/2022] Open
Abstract
Actin-depolymerization factor (ADF)/cofilin, a family of actin-binding proteins, are critical for the regulation of actin reorganization in response to various signals. Accumulating evidence indicates that ADF/cofilin also play important roles in neuronal structure and function, including long-term potentiation and depression. These are the most extensively studied forms of long-lasting synaptic plasticity and are widely regarded as cellular mechanisms underlying learning and memory. ADF/cofilin regulate synaptic function through their effects on dendritic spines and the trafficking of glutamate receptors, the principal mediator of excitatory synaptic transmission in vertebrates. Regulation of ADF/cofilin involves various signaling pathways converging on LIM domain kinases and slingshot phosphatases, which phosphorylate/inactivate and dephosphorylate/activate ADF/cofilin, respectively. Actin-depolymerization factor/cofilin activity is also regulated by other actin-binding proteins, activity-dependent subcellular distribution and protein translation. Abnormalities in ADF/cofilin have been associated with several neurodegenerative disorders such as Alzheimer’s disease. Therefore, investigating the roles of ADF/cofilin in the brain is not only important for understanding the fundamental processes governing neuronal structure and function, but also may provide potential therapeutic strategies to treat brain disorders.
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Affiliation(s)
- Youssif Ben Zablah
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada.,Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Neil Merovitch
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada.,Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Zhengping Jia
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada.,Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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5
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Pillet LE, Cresto N, Saillour Y, Ghézali G, Bemelmans AP, Livet J, Bienvenu T, Rouach N, Billuart P. The intellectual disability protein Oligophrenin-1 controls astrocyte morphology and migration. Glia 2020; 68:1729-1742. [PMID: 32073702 DOI: 10.1002/glia.23801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 01/31/2020] [Accepted: 02/05/2020] [Indexed: 02/06/2023]
Abstract
Astrocytes are involved in several aspects of neuronal development and properties which are altered in intellectual disability (ID). Oligophrenin-1 is a RhoGAP protein implicated in actin cytoskeleton regulation, and whose mutations are associated with X-linked ID. Oligophrenin-1 is expressed in neurons, where its functions have been widely reported at the synapse, as well as in glial cells. However, its roles in astrocytes are still largely unexplored. Using in vitro and in vivo models of oligophrenin1 disruption in astrocytes, we found that oligophrenin1 regulates at the molecular level the RhoA/ROCK/MLC2 pathway in astroglial cells. We also showed at the cellular level that oligophrenin1 modulates astrocyte morphology and migration both in vitro and in vivo, and is involved in glial scar formation. Altogether, these data suggest that oligophrenin1 deficiency alters not only neuronal but also astrocytic functions, which might contribute to the development of ID.
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Affiliation(s)
- Laure-Elise Pillet
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.,Doctoral School N°562, Paris Descartes University, Paris, France.,Institut Cochin, INSERM UMR 1016, CNRS UMR 8104, Université de Paris, Paris, France
| | - Noémie Cresto
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Yoann Saillour
- Institut Cochin, INSERM UMR 1016, CNRS UMR 8104, Université de Paris, Paris, France
| | - Grégory Ghézali
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Alexis-Pierre Bemelmans
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale, Institut de biologie François Jacob, MIRCen, and CNRS UMR 9199, Université Paris-Sud, Neurodegenerative Diseases Laboratory, Fontenay-aux-Roses, France
| | - Jean Livet
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Thierry Bienvenu
- Institut Cochin, INSERM UMR 1016, CNRS UMR 8104, Université de Paris, Paris, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Pierre Billuart
- Institut Cochin, INSERM UMR 1016, CNRS UMR 8104, Université de Paris, Paris, France
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Li X, Miao Y, Pal DS, Devreotes PN. Excitable networks controlling cell migration during development and disease. Semin Cell Dev Biol 2019; 100:133-142. [PMID: 31836289 DOI: 10.1016/j.semcdb.2019.11.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/21/2019] [Accepted: 11/01/2019] [Indexed: 12/30/2022]
Abstract
The directed movements of individual, groups, or sheets of cells at specific times in particular locations bring about form and complexity to developing organisms. Cells move by extending protrusions, such as macropinosomes, pseudopods, lamellipods, filopods, or blebs. Although many of the cytoskeletal components within these structures are known, less is known about the mechanisms that determine their location, number, and characteristics. Recent evidence suggests that control may be exerted by a signal transduction excitable network whose components and activities, including Ras, PI3K, TorC2, and phosphoinositides, self-organize on the plasma membrane and propagate in waves. The waves drive the various types of protrusions, which in turn, determine the modes of cell migration. Acute perturbations at specific points in the network produce abrupt shifts in protrusion type, including transitions from pseudopods to filopods or lamellipods. These observations have also contributed to a delineation of the signal transduction network, including candidate fast positive and delayed negative feedback loops. The network contains many oncogenes and tumor suppressors, and other molecules which have recently been implicated in developmental and metabolic abnormalities. Thus, the concept of signal transduction network excitability in cell migration can be used to understand disease states and morphological changes occurring in development.
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Affiliation(s)
- Xiaoguang Li
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Yuchuan Miao
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Dhiman Sankar Pal
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Peter N Devreotes
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
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Redolfi N, Galla L, Maset A, Murru L, Savoia E, Zamparo I, Gritti A, Billuart P, Passafaro M, Lodovichi C. Oligophrenin-1 regulates number, morphology and synaptic properties of adult-born inhibitory interneurons in the olfactory bulb. Hum Mol Genet 2017; 25:5198-5211. [PMID: 27742778 DOI: 10.1093/hmg/ddw340] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 09/28/2016] [Indexed: 12/27/2022] Open
Abstract
Among the X-linked genes associated with intellectual disability, Oligophrenin-1 (OPHN1) encodes for a Rho GTPase-activating protein, a key regulator of several developmental processes, such as dendrite and spine formation and synaptic activity. Inhibitory interneurons play a key role in the development and function of neuronal circuits. Whether a mutation of OPHN1 can affect morphology and synaptic properties of inhibitory interneurons remains poorly understood. To address these open questions, we studied in a well-established mouse model of X-linked intellectual disability, i.e. a line of mice carrying a null mutation of OPHN1, the development and function of adult generated inhibitory interneurons in the olfactory bulb. Combining quantitative morphological analysis and electrophysiological recordings we found that the adult generated inhibitory interneurons were dramatically reduced in number and exhibited a higher proportion of filopodia-like spines, with the consequences on their synaptic function, in OPHN1 ko mice. Furthermore, we found that olfactory behaviour was perturbed in OPHN1 ko mice. Chronic treatment with a Rho kinase inhibitor rescued most of the defects of the newly generated neurons. Altogether, our data indicated that OPHN1 plays a key role in regulating the number, morphology and function of adult-born inhibitory interneurons and contributed to identify potential therapeutic targets.
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Affiliation(s)
- Nelly Redolfi
- Neuroscience Institute - CNR, Padova, Italy.,VIMM Padova, Italy
| | - Luisa Galla
- Neuroscience Institute - CNR, Padova, Italy.,VIMM Padova, Italy
| | | | - Luca Murru
- Neuroscience Institute, CNR, Milano, Italy
| | | | | | - Angela Gritti
- San Raffaele Telethon Institute for Gene Therapy (TIGET) Milano, Italy
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Converging, Synergistic Actions of Multiple Stress Hormones Mediate Enduring Memory Impairments after Acute Simultaneous Stresses. J Neurosci 2017; 36:11295-11307. [PMID: 27807170 DOI: 10.1523/jneurosci.2542-16.2016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/16/2016] [Indexed: 11/21/2022] Open
Abstract
Stress influences memory, an adaptive process crucial for survival. During stress, hippocampal synapses are bathed in a mixture of stress-released molecules, yet it is unknown whether or how these interact to mediate the effects of stress on memory. Here, we demonstrate novel synergistic actions of corticosterone and corticotropin-releasing hormone (CRH) on synaptic physiology and dendritic spine structure that mediate the profound effects of acute concurrent stresses on memory. Spatial memory in mice was impaired enduringly after acute concurrent stresses resulting from loss of synaptic potentiation associated with disrupted structure of synapse-bearing dendritic spines. Combined application of the stress hormones corticosterone and CRH recapitulated the physiological and structural defects provoked by acute stresses. Mechanistically, corticosterone and CRH, via their cognate receptors, acted synergistically on the spine-actin regulator RhoA, promoting its deactivation and degradation, respectively, and destabilizing spines. Accordingly, blocking the receptors of both hormones, but not each alone, rescued memory. Therefore, the synergistic actions of corticosterone and CRH at hippocampal synapses underlie memory impairments after concurrent and perhaps also single, severe acute stresses, with potential implications to spatial memory dysfunction in, for example, posttraumatic stress disorder. SIGNIFICANCE STATEMENT Stress influences memory, an adaptive process crucial for survival. During stress, adrenal corticosterone and hippocampal corticotropin-releasing hormone (CRH) permeate memory-forming hippocampal synapses, yet it is unknown whether (and how) these hormones interact to mediate effects of stress. Here, we demonstrate novel synergistic actions of corticosterone and CRH on hippocampal synaptic plasticity and spine structure that mediate the memory-disrupting effects of stress. Combined application of both hormones provoked synaptic function collapse and spine disruption. Mechanistically, corticosterone and CRH synergized at the spine-actin regulator RhoA, promoting its deactivation and degradation, respectively, and destabilizing spines. Notably, blocking both hormones, but not each alone, prevented the enduring memory problems after acute concurrent stresses. Therefore, synergistic actions of corticosterone and CRH underlie enduring memory impairments after concurrent acute stresses, which might be relevant to spatial memory deficits described in posttraumatic stress disorder.
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9
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Impairments in dendrite morphogenesis as etiology for neurodevelopmental disorders and implications for therapeutic treatments. Neurosci Biobehav Rev 2016; 68:946-978. [PMID: 27143622 DOI: 10.1016/j.neubiorev.2016.04.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 02/08/2023]
Abstract
Dendrite morphology is pivotal for neural circuitry functioning. While the causative relationship between small-scale dendrite morphological abnormalities (shape, density of dendritic spines) and neurodevelopmental disorders is well established, such relationship remains elusive for larger-scale dendrite morphological impairments (size, shape, branching pattern of dendritic trees). Here, we summarize published data on dendrite morphological irregularities in human patients and animal models for neurodevelopmental disorders, with focus on autism and schizophrenia. We next discuss high-risk genes for these disorders and their role in dendrite morphogenesis. We finally overview recent developments in therapeutic attempts and we discuss how they relate to dendrite morphology. We find that both autism and schizophrenia are accompanied by dendritic arbor morphological irregularities, and that majority of their high-risk genes regulate dendrite morphogenesis. Thus, we present a compelling argument that, along with smaller-scale morphological impairments in dendrites (spines and synapse), irregularities in larger-scale dendrite morphology (arbor shape, size) may be an important part of neurodevelopmental disorders' etiology. We suggest that this should not be ignored when developing future therapeutic treatments.
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10
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Abstract
SUMMARY Stimuli that promote cell migration, such as chemokines, cytokines, and growth factors in metazoans and cyclic AMP in Dictyostelium, activate signaling pathways that control organization of the actin cytoskeleton and adhesion complexes. The Rho-family GTPases are a key convergence point of these pathways. Their effectors include actin regulators such as formins, members of the WASP/WAVE family and the Arp2/3 complex, and the myosin II motor protein. Pathways that link to the Rho GTPases include Ras GTPases, TorC2, and PI3K. Many of the molecules involved form gradients within cells, which define the front and rear of migrating cells, and are also established in related cellular behaviors such as neuronal growth cone extension and cytokinesis. The signaling molecules that regulate migration can be integrated to provide a model of network function. The network displays biochemical excitability seen as spontaneous waves of activation that propagate along the cell cortex. These events coordinate cell movement and can be biased by external cues to bring about directed migration.
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Affiliation(s)
- Peter Devreotes
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Alan Rick Horwitz
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908
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11
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Zhang T, Wei Y, Jiang X, Li J, Qiu S, Zhang S. Protection of photoreceptors by intravitreal injection of the Y-27632 Rho-associated protein kinase inhibitor in Royal College of Surgeons rats. Mol Med Rep 2015; 12:3655-3661. [PMID: 26043901 DOI: 10.3892/mmr.2015.3889] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Accepted: 04/10/2015] [Indexed: 11/06/2022] Open
Abstract
Retinitis pigmentosa (RP) is an inherited retinal disease, which is characteristic by degeneration of the rod and cone photoreceptors. The present study aimed to assess the protective effects on photoreceptors of intravitreal injection of Y‑27632, a specific inhibitor of Rho‑associated protein kinase (ROCK), in a Royal College of Surgeons (RCS) rat model. Different concentrations of Y‑27632 (1‑50 mM) were administered by intravitreal injection into the RCS rats. The effects of Y‑27632 were recorded using electroretinography (ERG), measuring the thicknesses of the retinal outer nuclear layer (ONL) and examination of apoptotic markers using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining and western blot analysis. Treatment of the eyes with Y27632 at 10 or 50 mM, led to a 30% increase in a‑ and b‑wave amplitudes in ERG, and an increase in ONL thickness by 10%, compared with the 1 mM Y‑27632‑treated and vehicle (phosphate‑buffered saline; PBS)‑treated groups. In addition, eyes treated with 10 mM Y27632 exhibited a 90% decrease in TUNEL‑positive cells, accompanied by decreased protein expression levels of active caspase 3 and Bax by 50%, and a 90% increase in the ratio of Bcl‑2/Bax, compared with the PBS‑treated groups. These data suggested that Y‑27632 protected retinal function by inhibiting the apoptosis of photoreceptor cells in the RCS rat model. The present study demonstrated for the first time, to the best of our knowledge, to report the use of Y‑27632 for protection against RP in an RCS rat model. Y‑27632 may be a potential candidate for the treatment of human RP.
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Affiliation(s)
- Ting Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑Sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Yantao Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑Sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xintong Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑Sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Jingming Li
- Department of Ophthalmology, Affiliated Eye Hospital of Nanchang University, Nanchang, Jiangxi 330000, P.R. China
| | - Suo Qiu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑Sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Shaochong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑Sen University, Guangzhou, Guangdong 510060, P.R. China
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12
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Lefort R. Reversing synapse loss in Alzheimer's disease: Rho-guanosine triphosphatases and insights from other brain disorders. Neurotherapeutics 2015; 12:19-28. [PMID: 25588580 PMCID: PMC4322073 DOI: 10.1007/s13311-014-0328-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Alzheimer's disease (AD) is a monumental public health crisis with no effective cure or treatment. To date, therapeutic strategies have focused almost exclusively on upstream signaling events in the disease, namely on β-amyloid and amyloid precursor protein processing, and have, unfortunately, yielded few, if any, promising results. An alternative approach may be to target signaling events downstream of β-amyloid and even tau. However, with so many pathways already linked to the disease, understanding which ones are "drivers" versus "passengers" in the pathogenesis of the disease remains a tremendous challenge. Given the critical roles of Rho-guanosine triphosphatases (GTPases) in regulating the actin cytoskeleton and spine dynamics, and the strong association between spine abnormalities and cognition, it is not surprising that mutations in a number of genes involved in Rho-GTPase signaling have been implicated in several brain disorders, including schizophrenia and autism. And now, there is mounting literature implicating Rho-GTPase signaling in AD pathogenesis as well. Here, I review this evidence, with a particular emphasis on the regulators of Rho-GTPase signaling, namely guanine nucleotide exchange factors and GTPase-activating proteins. Several of these have been linked to various aspects of AD, and each offers a novel potential therapeutic target for AD.
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Affiliation(s)
- Roger Lefort
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, and Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, 10032, USA,
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13
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De Filippis B, Nativio P, Fabbri A, Ricceri L, Adriani W, Lacivita E, Leopoldo M, Passarelli F, Fuso A, Laviola G. Pharmacological stimulation of the brain serotonin receptor 7 as a novel therapeutic approach for Rett syndrome. Neuropsychopharmacology 2014; 39:2506-18. [PMID: 24809912 PMCID: PMC4207333 DOI: 10.1038/npp.2014.105] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 04/29/2014] [Accepted: 04/30/2014] [Indexed: 01/01/2023]
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder, characterized by severe behavioral and physiological symptoms. Mutations in the methyl CpG-binding protein 2 gene (MECP2) cause >95% of classic cases, and currently there is no cure for this devastating disorder. The serotonin receptor 7 (5-HT7R) is linked to neuro-physiological regulation of circadian rhythm, mood, cognition, and synaptic plasticity. We presently report that 5-HT7R density is consistently reduced in cortical and hippocampal brain areas of symptomatic MeCP2-308 male mice, a RTT model. Systemic repeated treatment with LP-211 (0.25 mg/kg once/day for 7 days), a brain-penetrant selective 5-HT7R agonist, was able to rescue RTT-related defective performance: anxiety-related profiles in a Light/Dark test, motor abilities in a Dowel test, the exploratory behavior in the Marble Burying test, as well as memory in the Novelty Preference task. In the brain of RTT mice, LP-211 also reversed the abnormal activation of PAK and cofilin (key regulators of actin cytoskeleton dynamics) and of the ribosomal protein (rp) S6, whose reduced activation in MECP2 mutant neurons by mTOR is responsible for the altered protein translational control. Present findings indicate that pharmacological targeting of 5-HT7R improves specific behavioral and molecular manifestations of RTT, thus representing a first step toward the validation of an innovative systemic treatment. Beyond RTT, the latter might be extended to other disorders associated with intellectual disability.
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Affiliation(s)
- Bianca De Filippis
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Rome, Italy
| | - Paola Nativio
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Alessia Fabbri
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Rome, Italy
| | - Laura Ricceri
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Rome, Italy
| | - Walter Adriani
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Rome, Italy
| | - Enza Lacivita
- Department of Pharmacy, University of Bari ‘A Moro', Bari, Italy
| | | | | | - Andrea Fuso
- Department of Psychology, Section of Neuroscience, Sapienza University of Rome, Rome, Italy
- European Center for Brain Research (CERC)/IRCCS Santa Lucia Foundation, Rome, Italy
| | - Giovanni Laviola
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Rome, Italy
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14
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Travaglione S, Loizzo S, Ballan G, Fiorentini C, Fabbri A. The E. coli CNF1 as a pioneering therapy for the central nervous system diseases. Toxins (Basel) 2014; 6:270-82. [PMID: 24402235 PMCID: PMC3920261 DOI: 10.3390/toxins6010270] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/17/2013] [Accepted: 12/31/2013] [Indexed: 01/24/2023] Open
Abstract
The Cytotoxic Necrotizing Factor 1 (CNF1), a protein toxin from pathogenic E. coli, modulates the Rho GTPases, thus, directing the organization of the actin cytoskeleton. In the nervous system, the Rho GTPases play a key role in several processes, controlling the morphogenesis of dendritic spines and synaptic plasticity in brain tissues. This review is focused on the peculiar property of CNF1 to enhance brain plasticity in in vivo animal models of central nervous system (CNS) diseases, and on its possible application in therapy.
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Affiliation(s)
- Sara Travaglione
- Department of Therapeutic Research and Medicines Evaluation, Superior Health Institute, viale Regina Elena 299, Rome 00161, Italy.
| | - Stefano Loizzo
- Department of Therapeutic Research and Medicines Evaluation, Superior Health Institute, viale Regina Elena 299, Rome 00161, Italy.
| | - Giulia Ballan
- Department of Therapeutic Research and Medicines Evaluation, Superior Health Institute, viale Regina Elena 299, Rome 00161, Italy.
| | - Carla Fiorentini
- Department of Therapeutic Research and Medicines Evaluation, Superior Health Institute, viale Regina Elena 299, Rome 00161, Italy.
| | - Alessia Fabbri
- Department of Therapeutic Research and Medicines Evaluation, Superior Health Institute, viale Regina Elena 299, Rome 00161, Italy.
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15
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Hammond VE, Gunnersen JM, Goh CP, Low LH, Hyakumura T, Tang MM, Britto JM, Putz U, Howitt JA, Tan SS. Ndfip1 is required for the development of pyramidal neuron dendrites and spines in the neocortex. ACTA ACUST UNITED AC 2013; 24:3289-300. [PMID: 23897647 DOI: 10.1093/cercor/bht191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Ubiquitin ligases of the Nedd4 family are important for axon and dendrite development, but little is known about their adaptor, Nedd4 family-interacting protein 1 (Ndfip1), that is responsible for their enzymatic activation. To study the function of Ndfip1 in cortical development, we generated a conditional knock-out (conditional KO) in neurons. The Ndfip1 conditional KO mice were viable; however, cortical neurons in the adult brain exhibited atrophic characteristics, including stunted dendritic arbors, blebbing of dendrites, and fewer dendritic spines. In electron micrographs, these neurons appeared shrunken with compacted somata and involutions of the nuclear membrane. In culture, Ndfip1 KO neurons exhibited exuberant sprouting suggesting loss of developmental control. Biochemical analysis of postsynaptic density (PSD) fractions from Ndfip1 KO cortical and hippocampal neurons showed that the postsynaptic proteins (Arc and PSD-95) were reduced compared with wild-type controls. In addition, the PI3 kinase/Akt signaling pathway was altered. These results indicate that Ndfip1, through its Nedd4 effectors, is important for the development of dendrites and dendritic spines in the cortex.
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Affiliation(s)
| | - Jenny M Gunnersen
- Florey Institute of Neuroscience and Mental Health and Department of Anatomy and Neuroscience, The University of Melbourne, Victoria 3010, Australia
| | - Choo-Peng Goh
- Florey Institute of Neuroscience and Mental Health and
| | - Ley-Hian Low
- Florey Institute of Neuroscience and Mental Health and
| | | | | | | | - Ulrich Putz
- Florey Institute of Neuroscience and Mental Health and
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16
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Asrar S, Jia Z. Molecular mechanisms coordinating functional and morphological plasticity at the synapse: Role of GluA2/N-cadherin interaction-mediated actin signaling in mGluR-dependent LTD. Cell Signal 2013; 25:397-402. [DOI: 10.1016/j.cellsig.2012.11.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/05/2012] [Indexed: 11/25/2022]
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17
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Ricceri L, De Filippis B, Laviola G. Rett syndrome treatment in mouse models: searching for effective targets and strategies. Neuropharmacology 2012; 68:106-15. [PMID: 22940001 DOI: 10.1016/j.neuropharm.2012.08.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/08/2012] [Accepted: 08/13/2012] [Indexed: 11/24/2022]
Abstract
Rett syndrome (RTT) is a pervasive developmental disorder, primarily affecting girls with a prevalence of 1 in every 10,000 births; it represents the second most common cause of intellectual disability in females. Mutations in the gene encoding methyl-CpG-binding protein 2 (MECP2) have been identified as clear etiological factors in more than 90% of classical RTT cases. Whereas the mechanisms leading to the severe, progressive and specific neurological dysfunctions when this gene is mutated still remain to be elucidated, a series of different mouse models have been generated, bearing different Mecp2 mutation. Neurobehavioural analysis in these mouse lines have been carried out and phenotyping analysis can be now utilised to preclinically evaluate the effects of potential RTT treatments. This review summarizes the different results achieved in this research field taking into account different key targets identified to ameliorate RTT phenotype in mouse models, including those not directly downstream of MeCP2 and those limited to the early phases of postnatal development. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Laura Ricceri
- Section of Neurotoxicology and Neuroendocrinology, Dept. Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena, 299, I-00161 Roma, Italy
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18
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Maroteaux G, Loos M, van der Sluis S, Koopmans B, Aarts E, van Gassen K, Geurts A, Largaespada DA, Spruijt BM, Stiedl O, Smit AB, Verhage M. High-throughput phenotyping of avoidance learning in mice discriminates different genotypes and identifies a novel gene. GENES BRAIN AND BEHAVIOR 2012; 11:772-84. [PMID: 22846151 DOI: 10.1111/j.1601-183x.2012.00820.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/27/2012] [Accepted: 07/03/2012] [Indexed: 01/31/2023]
Abstract
Recognizing and avoiding aversive situations are central aspects of mammalian cognition. These abilities are essential for health and survival and are expected to have a prominent genetic basis. We modeled these abilities in eight common mouse inbred strains covering ∼75% of the species' natural variation and in gene-trap mice (>2000 mice), using an unsupervised, automated assay with an instrumented home cage (PhenoTyper) containing a shelter with two entrances. Mice visited this shelter for 20-1200 times/24 h and 71% of all mice developed a significant and often strong preference for one entrance. Subsequently, a mild aversive stimulus (shelter illumination) was automatically delivered when mice used their preferred entrance. Different genotypes developed different coping strategies. Firstly, the number of entries via the preferred entrance decreased in DBA/2J, C57BL/6J and 129S1/SvImJ, indicating that these genotypes associated one specific entrance with the aversive stimulus. Secondly, mice started sleeping outside (C57BL/6J, DBA/2J), indicating they associated the shelter, in general, with the aversive stimulus. Some mice showed no evidence for an association between the entrance and the aversive light, but did show markedly shorter shelter residence times in response to illumination, indicating they did perceive illumination as aversive. Finally, using this assay, we screened 43 different mutants, which yielded a novel gene, specc1/cytospinB. This mutant showed profound and specific delay in avoidance learning. Together, these data suggest that different genotypes express distinct learning and/or memory of associations between shelter entrance and aversive stimuli, and that specc1/cytospinB is involved in this aspect of cognition.
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Affiliation(s)
- G Maroteaux
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam and VU Medical Center, Amsterdam, The Netherlands
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19
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De Filippis B, Fabbri A, Simone D, Canese R, Ricceri L, Malchiodi-Albedi F, Laviola G, Fiorentini C. Modulation of RhoGTPases improves the behavioral phenotype and reverses astrocytic deficits in a mouse model of Rett syndrome. Neuropsychopharmacology 2012; 37:1152-63. [PMID: 22157810 PMCID: PMC3306877 DOI: 10.1038/npp.2011.301] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 10/28/2011] [Accepted: 10/28/2011] [Indexed: 11/09/2022]
Abstract
RhoGTPases are crucial molecules in neuronal plasticity and cognition, as confirmed by their role in non-syndromic mental retardation. Activation of brain RhoGTPases by the bacterial cytotoxic necrotizing factor 1 (CNF1) reshapes the actin cytoskeleton and enhances neurotransmission and synaptic plasticity in mouse brains. We evaluated the effects of a single CNF1 intracerebroventricular inoculation in a mouse model of Rett syndrome (RTT), a rare neurodevelopmental disorder and a genetic cause of mental retardation, for which no effective therapy is available. Fully symptomatic MeCP2-308 male mice were evaluated in a battery of tests specifically tailored to detect RTT-related impairments. At the end of behavioral testing, brain sections were immunohistochemically characterized. Magnetic resonance imaging and spectroscopy (MRS) were also applied to assess morphological and metabolic brain changes. The CNF1 administration markedly improved the behavioral phenotype of MeCP2-308 mice. CNF1 also dramatically reversed the evident signs of atrophy in astrocytes of mutant mice and restored wt-like levels of this cell population. A partial rescue of the overexpression of IL-6 cytokine was also observed in RTT brains. CNF1-induced brain metabolic changes detected by MRS analysis involved markers of glial integrity and bioenergetics, and point to improved mitochondria functionality in CNF1-treated mice. These results clearly indicate that modulation of brain RhoGTPases by CNF1 may constitute a totally innovative therapeutic approach for RTT and, possibly, for other disorders associated with mental retardation.
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Affiliation(s)
- Bianca De Filippis
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Alessia Fabbri
- Department Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Roma, Italy
| | - Daiana Simone
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Rossella Canese
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Laura Ricceri
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | | | - Giovanni Laviola
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Carla Fiorentini
- Department Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Roma, Italy
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20
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Hagerman R, Lauterborn J, Au J, Berry-Kravis E. Fragile X syndrome and targeted treatment trials. Results Probl Cell Differ 2012; 54:297-335. [PMID: 22009360 PMCID: PMC4114775 DOI: 10.1007/978-3-642-21649-7_17] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Work in recent years has revealed an abundance of possible new treatment targets for fragile X syndrome (FXS). The use of animal models, including the fragile X knockout mouse which manifests a phenotype very similar to FXS in humans, has resulted in great strides in this direction of research. The lack of Fragile X Mental Retardation Protein (FMRP) in FXS causes dysregulation and usually overexpression of a number of its target genes, which can cause imbalances of neurotransmission and deficits in synaptic plasticity. The use of metabotropic glutamate receptor (mGluR) blockers and gamma amino-butyric acid (GABA) agonists have been shown to be efficacious in reversing cellular and behavioral phenotypes, and restoring proper brain connectivity in the mouse and fly models. Proposed new pharmacological treatments and educational interventions are discussed in this chapter. In combination, these various targeted treatments show promising preliminary results in mitigating or even reversing the neurobiological abnormalities caused by loss of FMRP, with possible translational applications to other neurodevelopmental disorders including autism.
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Affiliation(s)
- Randi Hagerman
- Department of Pediatrics, University of California, Sacramento, CA, USA.
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21
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Ramakers GJA, Wolfer D, Rosenberger G, Kuchenbecker K, Kreienkamp HJ, Prange-Kiel J, Rune G, Richter K, Langnaese K, Masneuf S, Bösl MR, Fischer KD, Krugers HJ, Lipp HP, van Galen E, Kutsche K. Dysregulation of Rho GTPases in the αPix/Arhgef6 mouse model of X-linked intellectual disability is paralleled by impaired structural and synaptic plasticity and cognitive deficits. Hum Mol Genet 2011; 21:268-86. [PMID: 21989057 DOI: 10.1093/hmg/ddr457] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mutations in the ARHGEF6 gene, encoding the guanine nucleotide exchange factor αPIX/Cool-2 for the Rho GTPases Rac1 and Cdc42, cause X-linked intellectual disability (ID) in humans. We show here that αPix/Arhgef6 is primarily expressed in neuropil regions of the hippocampus. To study the role of αPix/Arhgef6 in neuronal development and plasticity and gain insight into the pathogenic mechanisms underlying ID, we generated αPix/Arhgef6-deficient mice. Gross brain structure in these mice appeared to be normal; however, analysis of Golgi-Cox-stained pyramidal neurons revealed an increase in both dendritic length and spine density in the hippocampus, accompanied by an overall loss in spine synapses. Early-phase long-term potentiation was reduced and long-term depression was increased in the CA1 hippocampal area of αPix/Arhgef6-deficient animals. Knockout animals exhibited impaired spatial and complex learning and less behavioral control in mildly stressful situations, suggesting that this model mimics the human ID phenotype. The structural and electrophysiological alterations in the hippocampus were accompanied by a significant reduction in active Rac1 and Cdc42, but not RhoA. In conclusion, we suggest that imbalance in activity of different Rho GTPases may underlie altered neuronal connectivity and impaired synaptic function and cognition in αPix/Arhgef6 knockout mice.
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Affiliation(s)
- Ger J A Ramakers
- Department of Neurons and Networks, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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22
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Rubenstein JLR. Annual Research Review: Development of the cerebral cortex: implications for neurodevelopmental disorders. J Child Psychol Psychiatry 2011; 52:339-55. [PMID: 20735793 PMCID: PMC3429600 DOI: 10.1111/j.1469-7610.2010.02307.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The cerebral cortex has a central role in cognitive and emotional processing. As such, understanding the mechanisms that govern its development and function will be central to understanding the bases of severe neuropsychiatric disorders, particularly those that first appear in childhood. In this review, I highlight recent progress in elucidating genetic, molecular and cellular mechanisms that control cortical development. I discuss basic aspects of cortical developmental anatomy, and mechanisms that regulate cortical size and area formation, with an emphasis on the roles of fibroblast growth factor (Fgf) signaling and specific transcription factors. I then examine how specific types of cortical excitatory projection neurons are generated, and how their axons grow along stereotyped pathways to their targets. Next, I address how cortical inhibitory (GABAergic) neurons are generated, and point out the role of these cells in controlling cortical plasticity and critical periods. The paper concludes with an examination of four possible developmental mechanisms that could contribute to some forms of neurodevelopmental disorders, such as autism.
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Affiliation(s)
- John L R Rubenstein
- Nina Ireland Laboratory of Developmental Neurobiology, Center for Neurobiology and Psychiatry, Department of Psychiatry, University of California at San Francisco, CA 94158-2324, USA.
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23
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Regulation of the postsynaptic cytoskeleton: roles in development, plasticity, and disorders. J Neurosci 2010; 30:14937-42. [PMID: 21068295 DOI: 10.1523/jneurosci.4276-10.2010] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The small size of dendritic spines belies the elaborate role they play in excitatory synaptic transmission and ultimately complex behaviors. The cytoskeletal architecture of the spine is predominately composed of actin filaments. These filaments, which at first glance might appear simple, are also surprisingly complex. They dynamically assemble into different structures and serve as a platform for orchestrating the elaborate responses of the spine during experience-dependent plasticity. This mini-symposium review will feature ongoing research into how spines are regulated by actin-signaling pathways during development and plasticity. It will also highlight evolving studies into how disruptions to these pathways might be functionally coupled to congenital disorders such as mental retardation.
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24
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p21-Activated kinases 1 and 3 control brain size through coordinating neuronal complexity and synaptic properties. Mol Cell Biol 2010; 31:388-403. [PMID: 21115725 DOI: 10.1128/mcb.00969-10] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The molecular mechanisms that coordinate postnatal brain enlargement, synaptic properties, and cognition remain an enigma. Here, we demonstrate that neuronal complexity controlled by p21-activated kinases (PAKs) is a key determinant for postnatal brain enlargement and synaptic properties. We showed that double-knockout (DK) mice lacking both PAK1 and PAK3 were born healthy, with normal brain size and structure, but severely impaired in postnatal brain growth, resulting in a dramatic reduction in brain volume. Remarkably, the reduced brain size was accompanied by minimal changes in total cell count, due to a significant increase in cell density. However, the DK neurons have smaller soma, markedly simplified dendritic arbors/axons, and reduced synapse density. Surprisingly, the DK mice had elevated basal synaptic responses due to enhanced individual synaptic potency but were severely impaired in bidirectional synaptic plasticity. The actions of PAK1 and PAK3 are possibly mediated by cofilin-dependent actin regulation, because the activity of cofilin and the properties of actin filaments were altered in the DK mice. These results reveal an essential in vivo role of PAK1 and PAK3 in coordinating neuronal complexity and synaptic properties and highlight the critical importance of dendrite/axon growth in dictating postnatal brain growth and attainment of normal brain size and function.
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25
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Regulation of synaptic Rac1 activity, long-term potentiation maintenance, and learning and memory by BCR and ABR Rac GTPase-activating proteins. J Neurosci 2010; 30:14134-44. [PMID: 20962234 DOI: 10.1523/jneurosci.1711-10.2010] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Rho family small GTPases are important regulators of neuronal development. Defective Rho regulation causes nervous system dysfunctions including mental retardation and Alzheimer's disease. Rac1, a member of the Rho family, regulates dendritic spines and excitatory synapses, but relatively little is known about how synaptic Rac1 is negatively regulated. Breakpoint cluster region (BCR) is a Rac GTPase-activating protein known to form a fusion protein with the c-Abl tyrosine kinase in Philadelphia chromosome-positive chronic myelogenous leukemia. Despite the fact that BCR mRNAs are abundantly expressed in the brain, the neural functions of BCR protein have remained obscure. We report here that BCR and its close relative active BCR-related (ABR) localize at excitatory synapses and directly interact with PSD-95, an abundant postsynaptic scaffolding protein. Mice deficient for BCR or ABR show enhanced basal Rac1 activity but only a small increase in spine density. Importantly, mice lacking BCR or ABR exhibit a marked decrease in the maintenance, but not induction, of long-term potentiation, and show impaired spatial and object recognition memory. These results suggest that BCR and ABR have novel roles in the regulation of synaptic Rac1 signaling, synaptic plasticity, and learning and memory, and that excessive Rac1 activity negatively affects synaptic and cognitive functions.
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26
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Kitsiou-Tzeli S, Tzetis M, Sofocleous C, Vrettou C, Xaidara A, Giannikou K, Pampanos A, Mavrou A, Kanavakis E. De novo interstitial duplication of the 15q11.2-q14 PWS/AS region of maternal origin: Clinical description, array CGH analysis, and review of the literature. Am J Med Genet A 2010; 152A:1925-32. [PMID: 20575009 DOI: 10.1002/ajmg.a.33447] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The 15q11-q13 PWS/AS critical region involves genes that are characterized by genomic imprinting. Multiple repeat elements within the region mediate rearrangements, including interstitial duplications, interstitial triplications, and supernumerary isodicentric marker chromosomes, as well as the deletions that cause Prader-Willi syndrome (PWS) and Angelman syndrome (AS). Recently, duplications of maternal origin concerning the same critical region have been implicated in autism spectrum disorders (ASD). We present a 6-month-old girl carrying a de novo duplication of maternal origin of the 15q11.2-q14 PWS/AS region (17.73 Mb in size) [46,XX,dup(15)(q11.2-q14)] detected with a high-resolution microarray-based comparative genomic hybridization (array-CGH). The patient is characterized by severe hypotonia, obesity, microstomia, long eyelashes, hirsutism, microretrognathia, short nose, severe psychomotor retardation, and multiple episodes of drug-resistant epileptic seizures, while her brain magnetic resonance imaging (MRI) documented partial corpus callosum dysplasia. In our patient the duplicated region is quite large extending beyond the Prader-Willi-Angelman critical region (PWACR), containing a number of genes that have been shown to be involved in ASD, exhibiting a severe phenotype, beyond the typical PWS/AS clinical manifestations. Reporting of similar well-characterized clinical cases with clearly delineated breakpoints of the duplicated region will clarify the contribution of specific genes to the phenotype.
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Affiliation(s)
- Sophia Kitsiou-Tzeli
- Department of Medical Genetics, Medical School, University of Athens, Athens, Greece
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27
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Porter FD, Herman GE. Malformation syndromes caused by disorders of cholesterol synthesis. J Lipid Res 2010; 52:6-34. [PMID: 20929975 DOI: 10.1194/jlr.r009548] [Citation(s) in RCA: 311] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cholesterol homeostasis is critical for normal growth and development. In addition to being a major membrane lipid, cholesterol has multiple biological functions. These roles include being a precursor molecule for the synthesis of steroid hormones, neuroactive steroids, oxysterols, and bile acids. Cholesterol is also essential for the proper maturation and signaling of hedgehog proteins, and thus cholesterol is critical for embryonic development. After birth, most tissues can obtain cholesterol from either endogenous synthesis or exogenous dietary sources, but prior to birth, the human fetal tissues are dependent on endogenous synthesis. Due to the blood-brain barrier, brain tissue cannot utilize dietary or peripherally produced cholesterol. Generally, inborn errors of cholesterol synthesis lead to both a deficiency of cholesterol and increased levels of potentially bioactive or toxic precursor sterols. Over the past couple of decades, a number of human malformation syndromes have been shown to be due to inborn errors of cholesterol synthesis. Herein, we will review clinical and basic science aspects of Smith-Lemli-Opitz syndrome, desmosterolosis, lathosterolosis, HEM dysplasia, X-linked dominant chondrodysplasia punctata, Congenital Hemidysplasia with Ichthyosiform erythroderma and Limb Defects Syndrome, sterol-C-4 methyloxidase-like deficiency, and Antley-Bixler syndrome.
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Affiliation(s)
- Forbes D Porter
- Program in Developmental Genetics and Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA.
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28
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Three hypotheses for developmental defects that may underlie some forms of autism spectrum disorder. Curr Opin Neurol 2010; 23:118-23. [PMID: 20087182 DOI: 10.1097/wco.0b013e328336eb13] [Citation(s) in RCA: 148] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
PURPOSE OF REVIEW Molecular and genetic insights into the etiology of autism spectrum disorders are now available. The field now needs to understand how these perturbations affect development and function of the brain. RECENT FINDINGS Herein I review the genetic mechanisms known to predispose to autism spectrum disorders, and attempt to consolidate many of these within cellular/molecular pathways that regulate development of neural systems that underlie cognition and social behaviors. In addition to the clear relationship of many susceptibility genes to activity-dependent neural responses, I propose the existence of three additional mechanisms that may contribute to autism spectrum disorders: evolutionary-driven expansion of cerebrum and cerebellar size; imbalance in the excitatory/inhibitory ratio in local and extended circuits; the hormonal effects of the male genotype. SUMMARY Understanding these mechanisms opens the possibility to therapeutic interventions.
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29
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Kiraly DD, Eipper-Mains JE, Mains RE, Eipper BA. Synaptic plasticity, a symphony in GEF. ACS Chem Neurosci 2010; 1:348-365. [PMID: 20543890 DOI: 10.1021/cn100012x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Dendritic spines are the postsynaptic sites for the majority of excitatory synapses in the mammalian forebrain. While many spines display great stability, others change shape in a matter of seconds to minutes. These rapid alterations in dendritic spine number and size require tight control of the actin cytoskeleton, the main structural component of dendritic spines. The ability of neurons to alter spine number and size is essential for the expression of neuronal plasticity. Within spines, guanine nucleotide exchange factors (GEFs) act as critical regulators of the actin cytoskeleton by controlling the activity of Rho-GTPases. In this review we focus on the Rho-GEFs expressed in the nucleus accumbens and localized to the postsynaptic density, and thus positioned to effect rapid alterations in the structure of dendritic spines. We review literature that ties these GEFs to different receptor systems and intracellular signaling cascades and discuss the effects these interactions are likely to have on synaptic plasticity.
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Affiliation(s)
- Drew D. Kiraly
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Jodi E. Eipper-Mains
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Richard E. Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Betty A. Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
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30
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Jiang XS, Backlund PS, Wassif CA, Yergey AL, Porter FD. Quantitative proteomics analysis of inborn errors of cholesterol synthesis: identification of altered metabolic pathways in DHCR7 and SC5D deficiency. Mol Cell Proteomics 2010; 9:1461-75. [PMID: 20305089 DOI: 10.1074/mcp.m900548-mcp200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Smith-Lemli-Opitz syndrome (SLOS) and lathosterolosis are malformation syndromes with cognitive deficits caused by mutations of 7-dehydrocholesterol reductase (DHCR7) and lathosterol 5-desaturase (SC5D), respectively. DHCR7 encodes the last enzyme in the Kandutsch-Russel cholesterol biosynthetic pathway, and impaired DHCR7 activity leads to a deficiency of cholesterol and an accumulation of 7-dehydrocholesterol. SC5D catalyzes the synthesis of 7-dehydrocholesterol from lathosterol. Impaired SC5D activity leads to a similar deficiency of cholesterol but an accumulation of lathosterol. Although the genetic and biochemical causes underlying both syndromes are known, the pathophysiological processes leading to the developmental defects remain unclear. To study the pathophysiological mechanisms underlying SLOS and lathosterolosis neurological symptoms, we performed quantitative proteomics analysis of SLOS and lathosterolosis mouse brain tissue and identified multiple biological pathways affected in Dhcr7(Delta3-5/Delta3-5) and Sc5d(-/-) E18.5 embryos. These include alterations in mevalonate metabolism, apoptosis, glycolysis, oxidative stress, protein biosynthesis, intracellular trafficking, and cytoskeleton. Comparison of proteome alterations in both Dhcr7(Delta3-5/Delta3-5) and Sc5d(-/-) brain tissues helps elucidate whether perturbed protein expression was due to decreased cholesterol or a toxic effect of sterol precursors. Validation of the proteomics results confirmed increased expression of isoprenoid and cholesterol synthetic enzymes. This alteration of isoprenoid synthesis may underlie the altered posttranslational modification of Rab7, a small GTPase that is functionally dependent on prenylation with geranylgeranyl, that we identified and validated in this study. These data suggested that although cholesterol synthesis is impaired in both Dhcr7(Delta3-5/Delta3-5) and Sc5d(-/-) embryonic brain tissues the synthesis of nonsterol isoprenoids may be increased and thus contribute to SLOS and lathosterolosis pathology. This proteomics study has provided insight into the pathophysiological mechanisms of SLOS and lathosterolosis, and understanding these pathophysiological changes will help guide clinical therapy for SLOS and lathosterolosis.
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Affiliation(s)
- Xiao-Sheng Jiang
- NICHD, National Institutes of Health, United States Department of Health and Human Services, Bethesda, Maryland 20892, USA.
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31
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Jiang XS, Wassif CA, Backlund PS, Song L, Holtzclaw LA, Li Z, Yergey AL, Porter FD. Activation of Rho GTPases in Smith-Lemli-Opitz syndrome: pathophysiological and clinical implications. Hum Mol Genet 2010; 19:1347-57. [PMID: 20067919 DOI: 10.1093/hmg/ddq011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a malformation syndrome with neurocognitive deficits due to mutations of DHCR7 that impair the reduction of 7-dehydrocholesterol to cholesterol. To investigate the pathological processes underlying the neurocognitive deficits, we compared protein expression in Dhcr7(+/+) and Dhcr7(Delta3-5/Delta3-5) brain tissue. One of the proteins identified was cofilin-1, an actin depolymerizing factor which regulates neuronal dendrite and axon formation. Differential expression of cofilin-1 was due to increased phosphorylation. Phosphorylation of cofilin-1 is regulated by Rho GTPases through Rho-Rock-Limk-Cofilin-1 and Rac/Cdc42-Pak-Limk-Cofilin-1 pathways. Pull-down assays were used to demonstrate increased activation of RhoA, Rac1 and Cdc42 in Dhcr7(Delta3-5/Delta3-5) brains. Consistent with increased activation of these Rho GTPases, we observed increased phosphorylation of both Limk and Pak in mutant brain tissue. Altered Rho/Rac signaling impairs normal dendritic and axonal formation, and mutations in genes encoding regulators and effectors of the Rho GTPases underlie other human mental retardation syndromes. Thus, we hypothesized that aberrant activation of Rho/Rac could have functional consequences for dendrite and axonal growth. In vitro analysis of Dhcr7(Delta3-5/Delta3-5) hippocampal neurons demonstrated both axonal and dendritic abnormalities. Developmental abnormalities of neuronal process formation may contribute to the neurocognitive deficits found in SLOS and may represent a potential target for therapeutic intervention.
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Affiliation(s)
- Xiao-Sheng Jiang
- Section on Molecular Dysmorphology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health, National Institutes of Health, Bethesda, MD 20892, USA
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32
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Crespi B, Summers K, Dorus S. Evolutionary genomics of human intellectual disability. Evol Appl 2010; 3:52-63. [PMID: 25567903 PMCID: PMC3352458 DOI: 10.1111/j.1752-4571.2009.00098.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 07/28/2009] [Indexed: 01/28/2023] Open
Abstract
Previous studies have postulated that X-linked and autosomal genes underlying human intellectual disability may have also mediated the evolution of human cognition. We have conducted the first comprehensive assessment of the extent and patterns of positive Darwinian selection on intellectual disability genes in humans. We report three main findings. First, as noted in some previous reports, intellectual disability genes with primary functions in the central nervous system exhibit a significant concentration to the X chromosome. Second, there was no evidence for a higher incidence of recent positive selection on X-linked than autosomal intellectual disability genes, nor was there a higher incidence of selection on such genes overall, compared to sets of control genes. However, the X-linked intellectual disability genes inferred to be subject to recent positive selection were concentrated in the Rho GTP-ase pathway, a key signaling pathway in neural development and function. Third, among all intellectual disability genes, there was evidence for a higher incidence of recent positive selection on genes involved in DNA repair, but not for genes involved in other functions. These results provide evidence that alterations to genes in the Rho GTP-ase and DNA-repair pathways may play especially-important roles in the evolution of human cognition and vulnerability to genetically-based intellectual disability.
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Affiliation(s)
- Bernard Crespi
- Department of Biosciences, Simon Fraser UniversityBurnaby, BC, Canada
| | - Kyle Summers
- Department of Biology, East Carolina UniversityGreenville, NC, USA
| | - Steve Dorus
- Department of Biology and Biochemistry, University of BathBath, UK
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33
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Focal adhesion kinase acts downstream of EphB receptors to maintain mature dendritic spines by regulating cofilin activity. J Neurosci 2009; 29:8129-42. [PMID: 19553453 DOI: 10.1523/jneurosci.4681-08.2009] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Dendritic spines are the postsynaptic sites of most excitatory synapses in the brain and are highly enriched in polymerized F-actin, which drives the formation and maintenance of mature dendritic spines and synapses. We propose that suppressing the activity of the actin-severing protein cofilin plays an important role in the stabilization of mature dendritic spines, and is accomplished through an EphB receptor-focal adhesion kinase (FAK) pathway. Our studies revealed that Cre-mediated knock-out of loxP-flanked fak prompted the reversion of mature dendritic spines to an immature filopodial-like phenotype in primary hippocampal cultures. The effects of FAK depletion on dendritic spine number, length, and morphology were rescued by the overexpression of the constitutively active FAK(Y397E), but not FAK(Y397F), indicating the significance of FAK activation by phosphorylation on tyrosine 397. Our studies demonstrate that FAK acts downstream of EphB receptors in hippocampal neurons and EphB2-FAK signaling controls the stability of mature dendritic spines by promoting cofilin phosphorylation, thereby inhibiting cofilin activity. While constitutively active nonphosphorylatable cofilin(S3A) induced an immature spine profile, phosphomimetic cofilin(S3D) restored mature spine morphology in neurons with disrupted EphB activity or lacking FAK. Further, we found that EphB-mediated regulation of cofilin activity at least partially depends on the activation of Rho-associated kinase (ROCK) and LIMK-1. These findings indicate that EphB2-mediated dendritic spine stabilization relies, in part, on the ability of FAK to activate the RhoA-ROCK-LIMK-1 pathway, which functions to suppress cofilin activity and inhibit cofilin-mediated dendritic spine remodeling.
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34
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Rex CS, Chen LY, Sharma A, Liu J, Babayan AH, Gall CM, Lynch G. Different Rho GTPase-dependent signaling pathways initiate sequential steps in the consolidation of long-term potentiation. ACTA ACUST UNITED AC 2009; 186:85-97. [PMID: 19596849 PMCID: PMC2712993 DOI: 10.1083/jcb.200901084] [Citation(s) in RCA: 229] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The releasable factor adenosine blocks the formation of long-term potentiation (LTP). These experiments used this observation to uncover the synaptic processes that stabilize the potentiation effect. Brief adenosine infusion blocked stimulation-induced actin polymerization within dendritic spines along with LTP itself in control rat hippocampal slices but not in those pretreated with the actin filament stabilizer jasplakinolide. Adenosine also blocked activity-driven phosphorylation of synaptic cofilin but not of synaptic p21-activated kinase (PAK). A search for the upstream origins of these effects showed that adenosine suppressed RhoA activity but only modestly affected Rac and Cdc42. A RhoA kinase (ROCK) inhibitor reproduced adenosine's effects on cofilin phosphorylation, spine actin polymerization, and LTP, whereas a Rac inhibitor did not. However, inhibitors of Rac or PAK did prolong LTP's vulnerability to reversal by latrunculin, a toxin which blocks actin filament assembly. Thus, LTP induction initiates two synaptic signaling cascades: one (RhoA-ROCK-cofilin) leads to actin polymerization, whereas the other (Rac-PAK) stabilizes the newly formed filaments.
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Affiliation(s)
- Christopher S Rex
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697, USA.
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35
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Nadif Kasri N, Nakano-Kobayashi A, Malinow R, Li B, Van Aelst L. The Rho-linked mental retardation protein oligophrenin-1 controls synapse maturation and plasticity by stabilizing AMPA receptors. Genes Dev 2009; 23:1289-302. [PMID: 19487570 DOI: 10.1101/gad.1783809] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Oligophrenin-1 (OPHN1) encodes a Rho-GTPase-activating protein (Rho-GAP) whose loss of function has been associated with X-linked mental retardation (MR). The pathophysiological role of OPHN1, however, remains poorly understood. Here we show that OPHN1 through its Rho-GAP activity plays a critical role in the activity-dependent maturation and plasticity of excitatory synapses by controlling their structural and functional stability. Synaptic activity through NMDA receptor activation drives OPHN1 into dendritic spines, where it forms a complex with AMPA receptors, and selectively enhances AMPA-receptor-mediated synaptic transmission and spine size by stabilizing synaptic AMPA receptors. Consequently, decreased or defective OPHN1 signaling prevents glutamatergic synapse maturation and causes loss of synaptic structure, function, and plasticity. These results imply that normal activity-driven glutamatergic synapse development is impaired by perturbation of OPHN1 function. Thus, our findings link genetic deficits in OPHN1 to glutamatergic dysfunction and suggest that defects in early circuitry development are an important contributory factor to this form of MR.
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Affiliation(s)
- Nael Nadif Kasri
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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36
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Haditsch U, Leone DP, Farinelli M, Chrostek-Grashoff A, Brakebusch C, Mansuy IM, McConnell SK, Palmer TD. A central role for the small GTPase Rac1 in hippocampal plasticity and spatial learning and memory. Mol Cell Neurosci 2009; 41:409-19. [PMID: 19394428 DOI: 10.1016/j.mcn.2009.04.005] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 04/17/2009] [Accepted: 04/17/2009] [Indexed: 10/20/2022] Open
Abstract
Rac1 is a member of the Rho family of small GTPases that are important for structural aspects of the mature neuronal synapse including basal spine density and shape, activity-dependent spine enlargement, and AMPA receptor clustering in vitro. Here we demonstrate that selective elimination of Rac1 in excitatory neurons in the forebrain in vivo not only affects spine structure, but also impairs synaptic plasticity in the hippocampus with consequent defects in hippocampus-dependent spatial learning. Furthermore, Rac1 mutants display deficits in working/episodic-like memory in the delayed matching-to-place (DMP) task suggesting that Rac1 is a central regulator of rapid encoding of novel spatial information in vivo.
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Affiliation(s)
- Ursula Haditsch
- Department of Neurosurgery, Stanford School of Medicine, 1201 Welch Rd, MSLS P304, Stanford, California 94305, USA.
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37
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Lin WH, Webb DJ. Actin and Actin-Binding Proteins: Masters of Dendritic Spine Formation, Morphology, and Function. THE OPEN NEUROSCIENCE JOURNAL 2009; 3:54-66. [PMID: 20717495 PMCID: PMC2921857 DOI: 10.2174/1874082000903020054] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dendritic spines are actin-rich protrusions that comprise the postsynaptic sites of synapses and receive the majority of excitatory synaptic inputs in the central nervous system. These structures are central to cognitive processes, and alterations in their number, size, and morphology are associated with many neurological disorders. Although the actin cytoskeleton is thought to govern spine formation, morphology, and synaptic functions, we are only beginning to understand how modulation of actin reorganization by actin-binding proteins (ABPs) contributes to the function of dendritic spines and synapses. In this review, we discuss what is currently known about the role of ABPs in regulating the formation, morphology, motility, and plasticity of dendritic spines and synapses.
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Affiliation(s)
- Wan-Hsin Lin
- Department of Biological Sciences and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Donna J. Webb
- Department of Biological Sciences and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
- Department of Cancer Biology, Vanderbilt University, Nashville, Tennessee 37235, USA
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38
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Kreis P, Barnier JV. PAK signalling in neuronal physiology. Cell Signal 2008; 21:384-93. [PMID: 19036346 DOI: 10.1016/j.cellsig.2008.11.001] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 11/06/2008] [Indexed: 12/11/2022]
Abstract
Group I p21-activated kinases are a family of key effectors of Rac1 and Cdc42 and they regulate many aspects of cellular function, such as cytoskeleton dynamics, cell movement and cell migration, cell proliferation and differentiation, and gene expression. The three genes PAK1/2/3 are expressed in brain and recent evidence indicates their crucial roles in neuronal cell fate, in axonal guidance and neuronal polarisation, and in neuronal migration. Moreover they are implicated in neurodegenerative diseases and play an important role in synaptic plasticity, with PAK3 being specifically involved in mental retardation. The main goal of this review is to describe the molecular mechanisms that govern the different functions of group I PAK in neuronal signalling and to discuss the specific functions of each isoform.
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Affiliation(s)
- Patricia Kreis
- CNRS, Institut de Neurobiologie Alfred Fessard-FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire-UPR9040, Gif sur Yvette, France.
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39
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Boda B, Jourdain L, Muller D. Distinct, but compensatory roles of PAK1 and PAK3 in spine morphogenesis. Hippocampus 2008; 18:857-61. [DOI: 10.1002/hipo.20451] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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The actin cross-linking protein AFAP120 regulates axon elongation in a tyrosine phosphorylation-dependent manner. Neurosci Lett 2008; 444:132-6. [PMID: 18723076 DOI: 10.1016/j.neulet.2008.08.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 06/30/2008] [Accepted: 08/04/2008] [Indexed: 01/30/2023]
Abstract
Growth cone guidance and axon elongation require the dynamic coordinated regulation of the actin cytoskeleton. As the growth cone moves, actin-dependent forces generate tension that enables protrusive activity in the periphery and drives growth cone translocation. This dynamic remodeling of the actin cytoskeleton in response to membrane tension requires activation of Src kinase. Although it has been proposed that these actin-dependent forces vary with the extent of actin cross-linking, the identity of the cross-linking protein(s) remains unknown. AFAP120 is a nervous system specific actin cross-linking protein that is regulated by Src kinase phosphorylation. Here, we report that AFAP120 is expressed and tyrosine phosphorylated in differentiating cerebellar granule cells, where it is enriched in the axon and growth cone. Over-expression of AFAP120 enhances neurite elongation in a tyrosine phosphorylation-dependent manner. These findings suggest that AFAP120 may coordinate Src signaling with the dynamic changes in the actin cytoskeleton that drive growth cone motility and axon elongation.
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41
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Zhou Z, Meng Y, Asrar S, Todorovski Z, Jia Z. A critical role of Rho-kinase ROCK2 in the regulation of spine and synaptic function. Neuropharmacology 2008; 56:81-9. [PMID: 18718479 DOI: 10.1016/j.neuropharm.2008.07.031] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 06/30/2008] [Accepted: 07/16/2008] [Indexed: 10/21/2022]
Abstract
The actin cytoskeleton is critically involved in the regulation of the dendritic spine and synaptic properties, but the molecular mechanisms underlying actin dynamics in neurons are poorly defined. We took genetic approaches to create and analyze knockout mice specifically lacking ROCK2, a protein kinase that directly interacts with and is activated by the Rho GTPases, the central mediator of actin reorganization. We demonstrated that while these knockout mice were normal in gross brain anatomy, they were impaired in both basal synaptic transmission and hippocampal long-term potentiation (LTP). Consistent with the electrophysiological deficits, the ROCK2 knockout neurons showed deficits in spine properties, synapse density, the actin cytoskeleton, and the actin-binding protein cofilin. These results indicate that ROCK2/cofilin signaling is critical in the regulation of neuronal actin, spine morphology and synaptic function.
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Affiliation(s)
- Zikai Zhou
- Neurosciences and Mental Health, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
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42
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Penzes P, Jones KA. Dendritic spine dynamics--a key role for kalirin-7. Trends Neurosci 2008; 31:419-27. [PMID: 18597863 PMCID: PMC3973420 DOI: 10.1016/j.tins.2008.06.001] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 05/23/2008] [Accepted: 06/02/2008] [Indexed: 11/20/2022]
Abstract
Changes in the structure and function of dendritic spines contribute to numerous physiological processes such as synaptic transmission and plasticity, as well as behavior, including learning and memory. Moreover, altered dendritic spine morphogenesis and plasticity is an endophenotype of many neurodevelopmental and neuropsychiatric disorders. Hence, the molecular mechanisms that control spine plasticity and pathology have been under intense investigation over the past few years. A series of recent studies has improved our understanding of spine dynamics by establishing kalirin-7 as an important regulator of dendritic spine development as well as structural and functional plasticity, providing a model for the molecular control of structural plasticity and implicating kalirin-7 in synaptic pathology in several disorders including schizophrenia and Alzheimer's disease.
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Affiliation(s)
- Peter Penzes
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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43
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Brunetti-Pierri N, Sahoo T, Frioux S, Chinault C, Zascavage R, Cheung SW, Peters S, Shinawi M. 15q13q14 deletions: Phenotypic characterization and molecular delineation by comparative genomic hybridization. Am J Med Genet A 2008; 146A:1933-41. [DOI: 10.1002/ajmg.a.32324] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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44
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Saneyoshi T, Wayman G, Fortin D, Davare M, Hoshi N, Nozaki N, Natsume T, Soderling TR. Activity-dependent synaptogenesis: regulation by a CaM-kinase kinase/CaM-kinase I/betaPIX signaling complex. Neuron 2008; 57:94-107. [PMID: 18184567 DOI: 10.1016/j.neuron.2007.11.016] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 08/17/2007] [Accepted: 11/21/2007] [Indexed: 01/04/2023]
Abstract
Neuronal activity augments maturation of mushroom-shaped spines to form excitatory synapses, thereby strengthening synaptic transmission. We have delineated a Ca(2+)-signaling pathway downstream of the NMDA receptor that stimulates calmodulin-dependent kinase kinase (CaMKK) and CaMKI to promote formation of spines and synapses in hippocampal neurons. CaMKK and CaMKI form a multiprotein signaling complex with the guanine nucleotide exchange factor (GEF) betaPIX and GIT1 that is localized in spines. CaMKI-mediated phosphorylation of Ser516 in betaPIX enhances its GEF activity, resulting in activation of Rac1, an established enhancer of spinogenesis. Suppression of CaMKK or CaMKI by pharmacological inhibitors, dominant-negative (dn) constructs and siRNAs, as well as expression of the betaPIX Ser516Ala mutant, decreases spine formation and mEPSC frequency. Constitutively-active Pak1, a downstream effector of Rac1, rescues spine inhibition by dnCaMKI or betaPIX S516A. This activity-dependent signaling pathway can promote synapse formation during neuronal development and in structural plasticity.
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Affiliation(s)
- Takeo Saneyoshi
- Vollum Institute, Oregon Health and Sciences University, Portland, OR 97239, USA
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45
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Kasri NN, Govek EE, Van Aelst L. Characterization of oligophrenin-1, a RhoGAP lost in patients affected with mental retardation: lentiviral injection in organotypic brain slice cultures. Methods Enzymol 2008; 439:255-66. [PMID: 18374170 DOI: 10.1016/s0076-6879(07)00419-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mutations in regulators and effectors of the Rho GTPases underlie various forms of mental retardation (MR). Among them, oligophrenin-1 (OPHN1), which encodes a Rho-GTPase activating protein, was one of the first Rho-linked MR genes identified. Upon characterization of OPHN1 in hippocampal brain slices, we obtained evidence for the requirement of OPHN1 in dendritic spine morphogenesis and neuronal function of CA1 pyramidal neurons. Organotypic hippocampal brain slice cultures are commonly used as a model system to investigate the morphology and synaptic function of neurons, mainly because they allow for the long-term examination of neurons in a preparation where the gross cellular architecture of the hippocampus is retained. In addition, maintenance of the trisynaptic circuitry in hippocampal slices enables the study of synaptic connections. Today, a multitude of gene transfer methods for postmitotic neurons in brain slices are available to easily manipulate and scrutinize the involvement of signaling molecules, such as Rho GTPases, in specific cellular processes in this system. This chapter covers techniques detailing the preparation and culturing of organotypic hippocampal brain slices, as well as the production and injection of lentivirus into brain slices.
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Affiliation(s)
- Nael Nadif Kasri
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
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46
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Nadif Kasri N, Van Aelst L. Rho-linked genes and neurological disorders. Pflugers Arch 2007; 455:787-97. [PMID: 18004590 DOI: 10.1007/s00424-007-0385-1] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Accepted: 10/29/2007] [Indexed: 12/11/2022]
Abstract
Mental retardation (MR) is a common cause of intellectual disability and affects approximately 2 to 3% of children and young adults. Many forms of MR are associated with abnormalities in dendritic structure and/or dendritic spine morphology. Given that dendritic spine morphology has been tightly linked to synaptic activity, altered spine morphology has been suggested to underlie or contribute to the cognitive disabilities associated with MR. The structure and dynamics of dendritic spines is determined by its underlying actin cytoskeleton. Signaling molecules and cascades important for cytoskeletal regulation have therefore attracted a great deal of attention. As key regulators of both the actin and microtubule cytoskeletons, it is not surprising that the Rho GTPases have emerged as important regulators of dendrite and spine structural plasticity. Significantly, mutations in regulators and effectors of Rho GTPases have been associated with diseases affecting the nervous system, including MR and amyotrophic lateral sclerosis (ALS). Here, we will discuss Rho GTPase-related genes and their signaling pathways involved in MR and ALS.
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Affiliation(s)
- Nael Nadif Kasri
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Demerec Building, Cold Spring Harbor, NY 11724, USA.
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47
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Petratos S, Li QX, George AJ, Hou X, Kerr ML, Unabia SE, Hatzinisiriou I, Maksel D, Aguilar MI, Small DH. The β-amyloid protein of Alzheimer's disease increases neuronal CRMP-2 phosphorylation by a Rho-GTP mechanism. Brain 2007; 131:90-108. [DOI: 10.1093/brain/awm260] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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48
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Khelfaoui M, Denis C, van Galen E, de Bock F, Schmitt A, Houbron C, Morice E, Giros B, Ramakers G, Fagni L, Chelly J, Nosten-Bertrand M, Billuart P. Loss of X-linked mental retardation gene oligophrenin1 in mice impairs spatial memory and leads to ventricular enlargement and dendritic spine immaturity. J Neurosci 2007; 27:9439-50. [PMID: 17728457 PMCID: PMC6673114 DOI: 10.1523/jneurosci.2029-07.2007] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Loss of oligophrenin1 (OPHN1) function in human causes X-linked mental retardation associated with cerebellar hypoplasia and, in some cases, with lateral ventricle enlargement. In vitro studies showed that ophn1 regulates dendritic spine through the control of Rho GTPases, but its in vivo function remains unknown. We generated a mouse model of ophn1 deficiency and showed that it mimics the ventricles enlargement without affecting the cerebellum morphoanatomy. The ophn1 knock-out mice exhibit behavioral defects in spatial memory together with impairment in social behavior, lateralization, and hyperactivity. Long-term potentiation and mGluR-dependent long-term depression are normal in the CA1 hippocampal area of ophn1 mutant, whereas paired-pulse facilitation is reduced. This altered short-term plasticity that reflects changes in the release of neurotransmitters from the presynaptic processes is associated with normal synaptic density together with a reduction in mature dendritic spines. In culture, inactivation of ophn1 function increases the density and proportion of immature spines. Using a conditional model of loss of ophn1 function, we confirmed this immaturity defect and showed that ophn1 is required at all the stages of the development. These studies show that, depending of the context, ophn1 controls the maturation of dendritic spines either by maintaining the density of mature spines or by limiting the extension of new filopodia. Altogether, these observations indicate that cognitive impairment related to OPHN1 loss of function is associated with both presynaptic and postsynaptic alterations.
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Affiliation(s)
- Malik Khelfaoui
- Department of Genetic and Development, Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (CNRS) [Unité Mixte de Recherche (UMR) 8104], F-75014 Paris, France
- Inserm, U567, F-75014 Paris, France
| | - Cécile Denis
- Inserm, U513, Neurobiology and Psychiatry, F-94010 Créteil, France
| | - Elly van Galen
- Netherlands Institute for Neurosciences, Neurons, and Networks, 1105 AZ Amsterdam, The Netherlands
| | - Frédéric de Bock
- Department of Neurobiology, Institut de Genomique Fonctionnelle, Université Montpellier 1 et 2, CNRS (UMR 5203), F-34094 Montpellier, France, and
- Inserm, U661, F-34094 Montpellier, France
| | - Alain Schmitt
- Department of Genetic and Development, Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (CNRS) [Unité Mixte de Recherche (UMR) 8104], F-75014 Paris, France
- Inserm, U567, F-75014 Paris, France
| | - Christophe Houbron
- Department of Genetic and Development, Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (CNRS) [Unité Mixte de Recherche (UMR) 8104], F-75014 Paris, France
- Inserm, U567, F-75014 Paris, France
| | - Elise Morice
- Inserm, U513, Neurobiology and Psychiatry, F-94010 Créteil, France
| | - Bruno Giros
- Inserm, U513, Neurobiology and Psychiatry, F-94010 Créteil, France
| | - Ger Ramakers
- Netherlands Institute for Neurosciences, Neurons, and Networks, 1105 AZ Amsterdam, The Netherlands
| | - Laurent Fagni
- Department of Neurobiology, Institut de Genomique Fonctionnelle, Université Montpellier 1 et 2, CNRS (UMR 5203), F-34094 Montpellier, France, and
- Inserm, U661, F-34094 Montpellier, France
| | - Jamel Chelly
- Department of Genetic and Development, Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (CNRS) [Unité Mixte de Recherche (UMR) 8104], F-75014 Paris, France
- Inserm, U567, F-75014 Paris, France
| | | | - Pierre Billuart
- Department of Genetic and Development, Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (CNRS) [Unité Mixte de Recherche (UMR) 8104], F-75014 Paris, France
- Inserm, U567, F-75014 Paris, France
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49
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Berto G, Camera P, Fusco C, Imarisio S, Ambrogio C, Chiarle R, Silengo L, Di Cunto F. The Down syndrome critical region protein TTC3 inhibits neuronal differentiation via RhoA and Citron kinase. J Cell Sci 2007; 120:1859-67. [PMID: 17488780 DOI: 10.1242/jcs.000703] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The Down syndrome critical region (DSCR) on Chromosome 21 contains many genes whose duplication may lead to the major phenotypic features of Down syndrome and especially the associated mental retardation. However, the functions of DSCR genes are mostly unknown and their possible involvement in key brain developmental events still largely unexplored. In this report we show that the protein TTC3, encoded by one of the main DSCR candidate genes, physically interacts with Citron kinase (CIT-K) and Citron N (CIT-N), two effectors of the RhoA small GTPase that have previously been involved in neuronal proliferation and differentiation. More importantly, we found that TTC3 levels can strongly affect the NGF-induced differentiation of PC12 cells, by a CIT-K-dependent mechanism. Indeed, TTC3 overexpression leads to strong inhibition of neurite extension, which can be reverted by CIT-K RNAi. Conversely, TTC3 knockdown stimulates neurite extension in the same cells. Finally, we find that Rho, but not Rho kinase, is required for TTC3 differentiation-inhibiting activity. Our results suggest that the TTC3-RhoA-CIT-K pathway could be a crucial determinant of in vivo neuronal development, whose hyperactivity may result in detrimental effects on the normal differentiation program.
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Affiliation(s)
- Gaia Berto
- Molecular Biotechnology Center, Department of Genetics, Biology and Biochemistry, University of Turin, Italy
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50
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Kreis P, Thévenot E, Rousseau V, Boda B, Muller D, Barnier JV. The p21-activated kinase 3 implicated in mental retardation regulates spine morphogenesis through a Cdc42-dependent pathway. J Biol Chem 2007; 282:21497-506. [PMID: 17537723 DOI: 10.1074/jbc.m703298200] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The p21-activated kinase 3 (PAK3) is one of the recently identified genes for which mutations lead to nonsyndromic mental retardation. PAK3 is implicated in dendritic spine morphogenesis and is a key regulator of synaptic functions. However, the underlying roles of PAK3 in these processes remain poorly understood. We report here that the three mutations R419X, A365E, and R67C, responsible for mental retardation have different effects on the biological functions of PAK3. The R419X and A365E mutations completely abrogate the kinase activity. The R67C mutation drastically decreases the binding of PAK3 to the small GTPase Cdc42 and impairs its subsequent activation by this GTPase. We also report that PAK3 binds significantly more Cdc42 than Rac1 and is selectively activated by endogenous Cdc42, suggesting that PAK3 is a specific effector of Cdc42. Interestingly, the expression of the three mutated proteins in hippocampal neurons affects spinogenesis differentially. Both kinase-dead mutants slightly decrease the number of spines but profoundly alter spine morphology, whereas expression of the R67C mutant drastically decreases spine density. These results demonstrate that the Cdc42/PAK3 is a key module in dendritic spine formation and synaptic plasticity.
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Affiliation(s)
- Patricia Kreis
- CNRS, Institut de Neurobiologie Alfred Fessard, FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire, UPR9040, 1 avenue de la terrasse, Gif sur Yvette, F-91198, France
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