1
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Lee P, Kim J, Choi IY, Pal R, Hui D, Marcario JK, Michaelis ML, Michaelis EK. Increases in anterograde axoplasmic transport in neurons of the hyper-glutamatergic, glutamate dehydrogenase 1 (Glud1) transgenic mouse: Effects of glutamate receptors on transport. J Neurochem 2024; 168:719-727. [PMID: 38124277 PMCID: PMC11102336 DOI: 10.1111/jnc.16035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/30/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023]
Abstract
The excitatory neurotransmitter glutamate has a role in neuronal migration and process elongation in the central nervous system (CNS). The effects of chronic glutamate hyperactivity on vesicular and protein transport within CNS neurons, that is, processes necessary for neurite growth, have not been examined previously. In this study, we measured the effects of lifelong hyperactivity of glutamate neurotransmission on axoplasmic transport in CNS neurons. We compared wild-type (wt) to transgenic (Tg) mice over-expressing the glutamate dehydrogenase gene Glud1 in CNS neurons and exhibiting increases in glutamate transmitter formation, release, and synaptic activation in brain throughout the lifespan. We found that Glud1 Tg as compared with wt mice exhibited increases in the rate of anterograde axoplasmic transport in neurons of the hippocampus measured in brain slices ex vivo, and in olfactory neurons measured in vivo. We also showed that the in vitro pharmacologic activation of glutamate synapses in wt mice led to moderate increases in axoplasmic transport, while exposure to selective inhibitors of ion channel forming glutamate receptors very significantly suppressed anterograde transport, suggesting a link between synaptic glutamate receptor activation and axoplasmic transport. Finally, axoplasmic transport in olfactory neurons of Tg mice in vivo was partially inhibited following 14-day intake of ethanol, a known suppressor of axoplasmic transport and of glutamate neurotransmission. The same was true for transport in hippocampal neurons in slices from Glud1 Tg mice exposed to ethanol for 2 h ex vivo. In conclusion, endogenous activity at glutamate synapses regulates and glutamate synaptic hyperactivity increases intraneuronal transport rates in CNS neurons.
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Affiliation(s)
- Phil Lee
- Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, Kansas 66160 USA
- Department of Radiology, University of Kansas Medical Center, Kansas City, Kansas 66160 USA
| | - Jieun Kim
- Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, Kansas 66160 USA
| | - In-Young Choi
- Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, Kansas 66160 USA
- Department of Radiology, University of Kansas Medical Center, Kansas City, Kansas 66160 USA
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas 66160 USA
| | - Ranu Pal
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS 66047, USA
| | - Dongwei Hui
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS 66047, USA
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66047, USA
| | - Joanne K. Marcario
- Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, Kansas 66160 USA
| | - Mary L. Michaelis
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS 66047, USA
| | - Elias K. Michaelis
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS 66047, USA
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2
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Lin G, Rennie M, Adeeko A, Scarlata S. The role of calcium in neuronal membrane tension and synaptic plasticity. Biochem Soc Trans 2024; 52:937-945. [PMID: 38533899 DOI: 10.1042/bst20231518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 03/28/2024]
Abstract
Calcium is a primary second messenger that plays a role in cellular functions including growth, movement and responses to drugs. The role that calcium plays in mediating communication between neurons by synaptic vesicle release is well established. This review focuses on the dependence of the physical properties of neuronal plasma membranes on calcium levels. After describing the key features of synaptic plasticity, we summarize the general role of calcium in cell function and the signaling pathways responsible for intracellular increase in calcium levels. We then present findings showing that increases in intracellular calcium levels cause neurites to contract and break synaptic connections by changes in membrane tension.
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Affiliation(s)
- Guanyu Lin
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, U.S.A
| | - Madison Rennie
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, U.S.A
| | - Ayobami Adeeko
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, U.S.A
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, U.S.A
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3
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Presynaptic AMPA Receptors in Health and Disease. Cells 2021; 10:cells10092260. [PMID: 34571906 PMCID: PMC8470629 DOI: 10.3390/cells10092260] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/23/2021] [Accepted: 08/26/2021] [Indexed: 01/04/2023] Open
Abstract
AMPA receptors (AMPARs) are ionotropic glutamate receptors that play a major role in excitatory neurotransmission. AMPARs are located at both presynaptic and postsynaptic plasma membranes. A huge number of studies investigated the role of postsynaptic AMPARs in the normal and abnormal functioning of the mammalian central nervous system (CNS). These studies highlighted that changes in the functional properties or abundance of postsynaptic AMPARs are major mechanisms underlying synaptic plasticity phenomena, providing molecular explanations for the processes of learning and memory. Conversely, the role of AMPARs at presynaptic terminals is as yet poorly clarified. Accruing evidence demonstrates that presynaptic AMPARs can modulate the release of various neurotransmitters. Recent studies also suggest that presynaptic AMPARs may possess double ionotropic-metabotropic features and that they are involved in the local regulation of actin dynamics in both dendritic and axonal compartments. In addition, evidence suggests a key role of presynaptic AMPARs in axonal pathology, in regulation of pain transmission and in the physiology of the auditory system. Thus, it appears that presynaptic AMPARs play an important modulatory role in nerve terminal activity, making them attractive as novel pharmacological targets for a variety of pathological conditions.
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4
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Metabotropic actions of kainate receptors modulating glutamate release. Neuropharmacology 2021; 197:108696. [PMID: 34274351 DOI: 10.1016/j.neuropharm.2021.108696] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/03/2021] [Accepted: 06/07/2021] [Indexed: 12/06/2022]
Abstract
Presynaptic kainate (KA) receptors (KARs) modulate GABA and glutamate release in the central nervous system of mammals. While some of the actions of KARs are ionotropic, metabotropic actions for these receptors have also been seen to modulate both GABA and glutamate release. In general, presynaptic KARs modulate glutamate release through their metabotropic actions in a biphasic manner, with low KA concentrations producing an increase in glutamate release and higher concentrations of KA driving weaker release of this neurotransmitter. Different molecular mechanisms are involved in this modulation of glutamate release, with a G-protein independent, Ca2+-calmodulin adenylate cyclase (AC) and protein kinase A (PKA) dependent mechanism facilitating glutamate release, and a G-protein, AC and PKA dependent mechanism mediating the decrease in neurotransmitter release. Here, we describe the events underlying the KAR modulation of glutamatergic transmission in different brain regions, addressing the possible functions of this modulation and proposing future research lines in this field.
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5
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Kainate receptors in the developing neuronal networks. Neuropharmacology 2021; 195:108585. [PMID: 33910033 DOI: 10.1016/j.neuropharm.2021.108585] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/15/2021] [Accepted: 04/16/2021] [Indexed: 12/14/2022]
Abstract
Kainate receptors (KARs) are highly expressed in the immature brain and have unique developmentally regulated functions that may be important in linking neuronal activity to morphogenesis during activity-dependent fine-tuning of the synaptic connectivity. Altered expression of KARs in the developing neural network leads to changes in glutamatergic connectivity and network excitability, which may lead to long-lasting changes in behaviorally relevant circuitries in the brain. Here, we summarize the current knowledge on physiological and morphogenic functions described for different types of KARs at immature neural circuitries, focusing on their roles in modulating synaptic transmission and plasticity as well as circuit maturation in the rodent hippocampus and amygdala. Finally, we discuss the emerging evidence suggesting that malfunction of KARs in the immature brain may contribute to the pathophysiology underlying developmentally originating neurological disorders.
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6
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Ryazantseva M, Englund J, Shintyapina A, Huupponen J, Shteinikov V, Pitkänen A, Partanen JM, Lauri SE. Kainate receptors regulate development of glutamatergic synaptic circuitry in the rodent amygdala. eLife 2020; 9:52798. [PMID: 32202495 PMCID: PMC7117908 DOI: 10.7554/elife.52798] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 03/22/2020] [Indexed: 12/13/2022] Open
Abstract
Perturbed information processing in the amygdala has been implicated in developmentally originating neuropsychiatric disorders. However, little is known on the mechanisms that guide formation and refinement of intrinsic connections between amygdaloid nuclei. We demonstrate that in rodents the glutamatergic connection from basolateral to central amygdala (BLA-CeA) develops rapidly during the first 10 postnatal days, before external inputs underlying amygdala-dependent behaviors emerge. During this restricted period of synaptic development, kainate-type of ionotropic glutamate receptors (KARs) are highly expressed in the BLA and tonically activated to regulate glutamate release via a G-protein-dependent mechanism. Genetic manipulation of this endogenous KAR activity locally in the newborn LA perturbed development of glutamatergic input to CeA, identifying KARs as a physiological mechanism regulating formation of the glutamatergic circuitry in the amygdala.
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Affiliation(s)
- Maria Ryazantseva
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Jonas Englund
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Alexandra Shintyapina
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Johanna Huupponen
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Vasilii Shteinikov
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland
| | - Asla Pitkänen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Juha M Partanen
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland
| | - Sari E Lauri
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
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7
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Lee SE, Jeong S, Lee U, Chang S. SGIP1α functions as a selective endocytic adaptor for the internalization of synaptotagmin 1 at synapses. Mol Brain 2019; 12:41. [PMID: 31053155 PMCID: PMC6499997 DOI: 10.1186/s13041-019-0464-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 04/16/2019] [Indexed: 11/10/2022] Open
Abstract
Proper sorting of exocytosed synaptic vesicle (SV) proteins into individual SVs during endocytosis is of the utmost importance for the fidelity of subsequent neurotransmission. Recent studies suggest that each SV protein is sorted into individual SVs by its own dedicated adaptors as well as by association between SV proteins. The SH3-containing GRB2-like protein 3-interacting protein 1 (SGIP1), an ortholog of Fer/Cip4 homology domain-only (FCHo) proteins, contains a μ-homology domain (μHD) and binds AP-2 and Eps15, thus functioning as an endocytic regulator of clathrin-mediated endocytosis (CME). Its longest isoform SGIP1α is predominantly expressed in the brain but the functional significance of SGIP1 in SV recycling remains unknown. Here, we found that SGIP1α, a brain-specific long isoform of SGIP1 binds synaptotagmin1 (Syt1) via its μHD and promotes the internalization of Syt1 on the neuronal surface. The small hairpin RNA (shRNA)-mediated knockdown (KD) of SGIP1α caused selective impairment of Syt1 internalization at hippocampal synapses and it was fully rescued by coexpression of the shRNA-resistant form of SGIP1α in KD neurons. We further found that the μHD of SGIP1α is structurally similar to those of AP-2 and stonin2, and mutations at Trp771 and Lys781, which correspond to Syt1-recognition motifs of AP-2 and stonin2, to Ala bound less efficiently to Syt1 and failed to rescue the endocytic defect of Syt1 caused by KD. Our results indicate that SGIP1α is an endocytic adaptor dedicated to the retrieval of surface-stranded Syt1. Since endocytic sorting of Syt1 is also mediated by the overlapping activities of synaptic vesicle glycoprotein 2A/B (SV2A/B) and stonin2, our results suggest that complementary fail-safe mechanism by these proteins ensures high fidelity of Syt1 retrieval.
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Affiliation(s)
- Sang-Eun Lee
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Soomin Jeong
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Unghwi Lee
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Sunghoe Chang
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea.
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8
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Pyk2 Signaling through Graf1 and RhoA GTPase Is Required for Amyloid-β Oligomer-Triggered Synapse Loss. J Neurosci 2019; 39:1910-1929. [PMID: 30626696 DOI: 10.1523/jneurosci.2983-18.2018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 12/20/2018] [Accepted: 12/22/2018] [Indexed: 12/15/2022] Open
Abstract
The intracellular tyrosine kinase Pyk2 (PTK2B) is related to focal adhesion kinase and localizes to postsynaptic sites in brain. Pyk2 genetic variation contributes to late onset Alzheimer's disease (AD) risk. We recently observed that Pyk2 is required for synapse loss and for learning deficits in a transgenic mouse model of AD. Here, we explore the cellular and biochemical basis for the action of Pyk2 tyrosine kinase in amyloid-β oligomer (Aβo)-induced dendritic spine loss. Overexpression of Pyk2 reduces dendritic spine density of hippocampal neurons by a kinase-dependent mechanism. Biochemical isolation of Pyk2-interacting proteins from brain identifies Graf1c, a RhoA GTPase-activating protein inhibited by Pyk2. Aβo-induced reductions in dendritic spine motility and chronic spine loss require both Pyk2 kinase and RhoA activation. Thus, Pyk2 functions at postsynaptic sites to modulate F-actin control by RhoA and regulate synapse maintenance of relevance to AD risk.SIGNIFICANCE STATEMENT Genetic variation at the Pyk2 locus is a risk for Alzheimer's disease. We have observed that Pyk2 is required for AD transgenic synapse loss and memory dysfunction. However, the cellular and biochemical basis for Pyk2 function related to AD is not defined. Here, we show that brain Pyk2 interacts with the RhoGAP protein Graf1 to alter dendritic spine stability via RhoA GTPase. Amyloid-β oligomer-induced dendritic spine loss requires the Pyk2/Graf1 pathway.
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9
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The acetylation of cyclin-dependent kinase 5 at lysine 33 regulates kinase activity and neurite length in hippocampal neurons. Sci Rep 2018; 8:13676. [PMID: 30209341 PMCID: PMC6135752 DOI: 10.1038/s41598-018-31785-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 08/19/2018] [Indexed: 01/06/2023] Open
Abstract
Cyclin-dependent kinase 5 (CDK5) plays a pivotal role in neural development and neurodegeneration. CDK5 activity can be regulated by posttranslational modifications, including phosphorylation and S-nitrosylation. In this study, we demonstrate a novel mechanism by which the acetylation of CDK5 at K33 (Ac-CDK5) results in the loss of ATP binding and impaired kinase activity. We identify GCN5 and SIRT1 as critical factor controlling Ac-CDK5 levels. Ac-CDK5 achieved its lowest levels in rat fetal brains but was dramatically increased during postnatal periods. Intriguingly, nuclear Ac-CDK5 levels negatively correlated with neurite length in embryonic hippocampal neurons. Either treatment with the SIRT1 activator SRT1720 or overexpression of SIRT1 leads to increases in neurite length, whereas SIRT1 inhibitor EX527 or ectopic expression of acetyl-mimetic (K33Q) CDK5 induced the opposite effect. Furthermore, the expression of nuclear-targeted CDK5 K33Q abolished the SRT1720-induced neurite outgrowth, showing that SIRT1 positively regulates neurite outgrowth via deacetylation of nuclear CDK5. The CDK5 activity-dependent increase of neurite length was mediated by enhanced transcriptional regulation of BDNF via unknown mechanism(s). Our findings identify a novel mechanism by which acetylation-mediated regulation of nuclear CDK5 activity plays a critical role in determining neurite length in embryonic neurons.
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10
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Lee AR, Kim S, Ko KW, Park CS. Differential effects of N-linked glycosylation of Vstm5 at multiple sites on surface expression and filopodia formation. PLoS One 2017; 12:e0181257. [PMID: 28746350 PMCID: PMC5528877 DOI: 10.1371/journal.pone.0181257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 06/28/2017] [Indexed: 12/15/2022] Open
Abstract
V-set and transmembrane domain-containing protein 5 (Vstm5), a newly characterized small membrane glycoprotein, can induce membrane protrusions in various cells. Vstm5 can modulate both the position and complexity of central neurons by altering their membrane morphology and dynamics. In this study, we investigated the significance of glycosylation in the expression and function of Vstm5. Four N-linked glycosylation sites (Asn43, Asn87, Asn101, and Asn108) are predicted to be located in the extracellular N-terminus of mouse Vstm5. Although all four sites were glycosylated, their functional roles may not be identical. N-glycosylation at multiple sites affects differentially the function of Vstm5. Glycosylation at individual sites not only played essential roles in surface expression of Vstm5 but also in the formation of neuronal dendritic filopodia. These results indicate that N-linked glycosylation at multiple sites plays important roles by differentially influencing the expression, targeting, and biological activity of Vstm5.
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Affiliation(s)
- A-Ram Lee
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
- Bioimaging Research Center, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Sulgi Kim
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Kwang Woo Ko
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Chul-Seung Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
- Bioimaging Research Center, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
- * E-mail:
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11
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Putative Cell Adhesion Membrane Protein Vstm5 Regulates Neuronal Morphology and Migration in the Central Nervous System. J Neurosci 2016; 36:10181-97. [PMID: 27683913 DOI: 10.1523/jneurosci.0541-16.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 08/16/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED During brain development, dynamic changes in neuronal membranes perform critical roles in neuronal morphogenesis and migration to create functional neural circuits. Among the proteins that induce membrane dynamics, cell adhesion molecules are important in neuronal membrane plasticity. Here, we report that V-set and transmembrane domain-containing protein 5 (Vstm5), a cell-adhesion-like molecule belonging to the Ig superfamily, was found in mouse brain. Knock-down of Vstm5 in cultured hippocampal neurons markedly reduced the complexity of dendritic structures, as well as the number of dendritic filopodia. Vstm5 also regulates neuronal morphology by promoting dendritic protrusions that later develop into dendritic spines. Using electroporation in utero, we found that Vstm5 overexpression delayed neuronal migration and induced multiple branches in leading processes during corticogenesis. These results indicate that Vstm5 is a new cell-adhesion-like molecule and is critically involved in synaptogenesis and corticogenesis by promoting neuronal membrane dynamics. SIGNIFICANCE STATEMENT Neuronal migration and morphogenesis play critical roles in brain development and function. In this study, we demonstrate for the first time that V-set and transmembrane domain-containing protein 5 (Vstm5), a putative cell adhesion membrane protein, modulates both the position and complexity of central neurons by altering their membrane morphology and dynamics. Vstm5 is also one of the target genes responsible for variations in patient responses to treatments for major depressive disorder. Our results provide the first evidence that Vstm5 is a novel factor involved in the modulation of the neuronal membrane and a critical element in normal neural circuit formation during mammalian brain development.
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12
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Sphingosine-1-Phosphate (S1P) Impacts Presynaptic Functions by Regulating Synapsin I Localization in the Presynaptic Compartment. J Neurosci 2016; 36:4624-34. [PMID: 27098703 DOI: 10.1523/jneurosci.3588-15.2016] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/16/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Growing evidence indicates that sphingosine-1-P (S1P) upregulates glutamate secretion in hippocampal neurons. However, the molecular mechanisms through which S1P enhances excitatory activity remain largely undefined. The aim of this study was to identify presynaptic targets of S1P action controlling exocytosis. Confocal analysis of rat hippocampal neurons showed that S1P applied at nanomolar concentration alters the distribution of Synapsin I (SynI), a presynaptic phosphoprotein that controls the availability of synaptic vesicles for exocytosis. S1P induced SynI relocation to extrasynaptic regions of mature neurons, as well as SynI dispersion from synaptic vesicle clusters present at axonal growth cones of developing neurons. S1P-induced SynI relocation occurred in a Ca(2+)-independent but ERK-dependent manner, likely through the activation of S1P3 receptors, as it was prevented by the S1P3 receptor selective antagonist CAY1044 and in neurons in which S1P3 receptor was silenced. Our recent evidence indicates that microvesicles (MVs) released by microglia enhance the metabolism of endogenous sphingolipids in neurons and stimulate excitatory transmission. We therefore investigated whether MVs affect SynI distribution and whether endogenous S1P could be involved in the process. Analysis of SynI immunoreactivity showed that exposure to microglial MVs induces SynI mobilization at presynaptic sites and growth cones, whereas the use of inhibitors of sphingolipid cascade identified S1P as the sphingolipid mediating SynI redistribution. Our data represent the first demonstration that S1P induces SynI mobilization from synapses, thereby indicating the phosphoprotein as a novel target through which S1P controls exocytosis. SIGNIFICANCE STATEMENT Growing evidence indicates that the bioactive lipid sphingosine and its metabolite sphingosine-1-P (S1P) stimulate excitatory transmission. While it has been recently clarified that sphingosine influences directly the exocytotic machinery by activating the synaptic vesicle protein VAMP2 to form SNARE fusion complexes, the molecular mechanism by which S1P promotes neurotransmission remained largely undefined. In this study, we identify Synapsin I, a presynaptic phosphoprotein involved in the control of availability of synaptic vesicles for exocytosis, as the key target of S1P action. In addition, we provide evidence that S1P can be produced at mature axon terminals as well as at immature growth cones in response to microglia-derived signals, which may be important to stabilize nascent synapses and to restore or potentiate transmission.
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13
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Endosome-mediated endocytic mechanism replenishes the majority of synaptic vesicles at mature CNS synapses in an activity-dependent manner. Sci Rep 2016; 6:31807. [PMID: 27534442 PMCID: PMC4989163 DOI: 10.1038/srep31807] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 07/26/2016] [Indexed: 11/30/2022] Open
Abstract
Whether synaptic vesicles (SVs) are recovered via endosome-mediated pathways is a matter of debate; however, recent evidence suggests that clathrin-independent bulk endocytosis (CIE) via endosomes is functional and preferentially replenishes SV pools during strong stimulation. Here, using brefeldin-A (BFA) to block CIE, we found that CIE retrieved a minority of SVs at developing CNS synapses during strong stimulation, but its contribution increased up to 61% at mature CNS synapses. Contrary to previous views, BFA not only blocked SV formation from the endosome but also blocked the endosome formation at the plasma membrane. Adaptor protein 1 and 3 (AP-1/3) have key roles in SV reformation from endosomes during CIE, and AP-1 also affects bulk endosome formation from the plasma membrane. Finally, temporary blocking of chronic or acute neuronal activity with tetrodotoxin in mature neurons redirected most SV retrieval to endosome-independent pathways. These results show that during high neuronal activity, CIE becomes the major endocytic pathway at mature CNS synapses. Moreover, mature neurons use clathrin-mediated endocytosis and the CIE pathway to different extents depending on their previous activity; this may result in activity-dependent alterations of the SV composition which ultimately influence transmitter release and contribute to synaptic plasticity.
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14
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Lee FHF, Su P, Xie YF, Wang KE, Wan Q, Liu F. Disrupting GluA2-GAPDH Interaction Affects Axon and Dendrite Development. Sci Rep 2016; 6:30458. [PMID: 27461448 PMCID: PMC4962050 DOI: 10.1038/srep30458] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 07/06/2016] [Indexed: 12/31/2022] Open
Abstract
GluA2-containing AMPA receptors (AMPARs) play a critical role in various aspects of neurodevelopment. However, the molecular mechanisms underlying these processes are largely unknown. We report here that the interaction between GluA2 and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is necessary for neuron and cortical development. Using an interfering peptide (GluA2-G-Gpep) that specifically disrupts this interaction, we found that primary neuron cultures with peptide treatment displayed growth cone development deficits, impairment of axon formation, less dendritic arborization and lower spine protrusion density. Consistently, in vivo data with mouse brains from pregnant dams injected with GluA2-G-Gpep daily during embryonic day 8 to 19 revealed a reduction of cortical tract axon integrity and neuronal density in post-natal day 1 offspring. Disruption of GluA2-GAPDH interaction also impairs the GluA2-Plexin A4 interaction and reduces p53 acetylation in mice, both of which are possible mechanisms leading to the observed neurodevelopmental abnormalities. Furthermore, electrophysiological experiments indicate altered long-term potentiation (LTP) in hippocampal slices of offspring mice. Our results provide novel evidence that AMPARs, specifically the GluA2 subunit via its interaction with GAPDH, play a critical role in cortical neurodevelopment.
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Affiliation(s)
- Frankie Hang Fung Lee
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 Canada
| | - Ping Su
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 Canada
| | - Yu-Feng Xie
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 Canada
| | - Kyle Ethan Wang
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 Canada
| | - Qi Wan
- Department of Physiology, School of Medicine, Wuhan University, Wuhan 430071, China
| | - Fang Liu
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 Canada
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15
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Sakha P, Vesikansa A, Orav E, Heikkinen J, Kukko-Lukjanov TK, Shintyapina A, Franssila S, Jokinen V, Huttunen HJ, Lauri SE. Axonal Kainate Receptors Modulate the Strength of Efferent Connectivity by Regulating Presynaptic Differentiation. Front Cell Neurosci 2016; 10:3. [PMID: 26834558 PMCID: PMC4720004 DOI: 10.3389/fncel.2016.00003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 01/04/2016] [Indexed: 11/13/2022] Open
Abstract
Kainate type of glutamate receptors (KARs) are highly expressed during early brain development and may influence refinement of the circuitry, via modulating synaptic transmission and plasticity. KARs are also localized to axons, however, their exact roles in regulating presynaptic processes remain controversial. Here, we have used a microfluidic chamber system allowing specific manipulation of KARs in presynaptic neurons to study their functions in synaptic development and function in vitro. Silencing expression of endogenous KARs resulted in lower density of synaptophysin immunopositive puncta in microfluidically isolated axons. Various recombinant KAR subunits and pharmacological compounds were used to dissect the mechanisms behind this effect. The calcium permeable (Q) variants of the low-affinity (GluK1–3) subunits robustly increased synaptophysin puncta in axons in a manner that was dependent on receptor activity and PKA and PKC dependent signaling. Further, an associated increase in the mean active zone length was observed in electron micrographs. Selective presynaptic expression of these subunits resulted in higher success rate of evoked EPSCs consistent with higher probability of glutamate release. In contrast, the calcium-impermeable (R) variant of GluK1 or the high-affinity subunits (GluK4,5) had no effect on synaptic density or transmission efficacy. These data suggest that calcium permeable axonal KARs promote efferent connectivity by increasing the density of functional presynaptic release sites.
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Affiliation(s)
- Prasanna Sakha
- Neuroscience Center, University of HelsinkiHelsinki, Finland; Department of Biosciences, University of HelsinkiHelsinki, Finland
| | - Aino Vesikansa
- Neuroscience Center, University of HelsinkiHelsinki, Finland; Department of Biosciences, University of HelsinkiHelsinki, Finland
| | - Ester Orav
- Neuroscience Center, University of HelsinkiHelsinki, Finland; Department of Biosciences, University of HelsinkiHelsinki, Finland
| | - Joonas Heikkinen
- Departments of Materials Science and Engineering, Aalto University Espoo, Finland
| | - Tiina-Kaisa Kukko-Lukjanov
- Neuroscience Center, University of HelsinkiHelsinki, Finland; Department of Veterinary Biosciences, University of HelsinkiHelsinki, Finland
| | - Alexandra Shintyapina
- Neuroscience Center, University of HelsinkiHelsinki, Finland; Department of Biosciences, University of HelsinkiHelsinki, Finland
| | - Sami Franssila
- Departments of Materials Science and Engineering, Aalto University Espoo, Finland
| | - Ville Jokinen
- Departments of Materials Science and Engineering, Aalto University Espoo, Finland
| | | | - Sari E Lauri
- Neuroscience Center, University of HelsinkiHelsinki, Finland; Department of Biosciences, University of HelsinkiHelsinki, Finland
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16
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Hsu WL, Chung HW, Wu CY, Wu HI, Lee YT, Chen EC, Fang W, Chang YC. Glutamate Stimulates Local Protein Synthesis in the Axons of Rat Cortical Neurons by Activating α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors and Metabotropic Glutamate Receptors. J Biol Chem 2015; 290:20748-20760. [PMID: 26134564 DOI: 10.1074/jbc.m115.638023] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Indexed: 12/20/2022] Open
Abstract
Glutamate is the principal excitatory neurotransmitter in the mammalian CNS. By analyzing the metabolic incorporation of azidohomoalanine, a methionine analogue, in newly synthesized proteins, we find that glutamate treatments up-regulate protein translation not only in intact rat cortical neurons in culture but also in the axons emitting from cortical neurons before making synapses with target cells. The process by which glutamate stimulates local translation in axons begins with the binding of glutamate to the ionotropic AMPA receptors and metabotropic glutamate receptor 1 and members of group 2 metabotropic glutamate receptors on the plasma membrane. Subsequently, the activated mammalian target of rapamycin (mTOR) signaling pathway and the rise in Ca(2+), resulting from Ca(2+) influxes through calcium-permeable AMPA receptors, voltage-gated Ca(2+) channels, and transient receptor potential canonical channels, in axons stimulate the local translation machinery. For comparison, the enhancement effects of brain-derived neurotrophic factor (BDNF) on the local protein synthesis in cortical axons were also studied. The results indicate that Ca(2+) influxes via transient receptor potential canonical channels and activated the mTOR pathway in axons also mediate BDNF stimulation to local protein synthesis. However, glutamate- and BDNF-induced enhancements of translation in axons exhibit different kinetics. Moreover, Ca(2+) and mTOR signaling appear to play roles carrying different weights, respectively, in transducing glutamate- and BDNF-induced enhancements of axonal translation. Thus, our results indicate that exposure to transient increases of glutamate and more lasting increases of BDNF would stimulate local protein synthesis in migrating axons en route to their targets in the developing brain.
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Affiliation(s)
- Wei-Lun Hsu
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Hui-Wen Chung
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Chih-Yueh Wu
- Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Huei-Ing Wu
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Yu-Tao Lee
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - En-Chan Chen
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Weilun Fang
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Yen-Chung Chang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan; Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu 300, Taiwan; Institute of Nanoengineering and Microsystems, National Tsing Hua University, Hsinchu 300, Taiwan.
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17
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Transmembrane AMPAR regulatory protein γ-2 is required for the modulation of GABA release by presynaptic AMPARs. J Neurosci 2015; 35:4203-14. [PMID: 25762667 DOI: 10.1523/jneurosci.4075-14.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Presynaptic ionotropic glutamate receptors (iGluRs) play important roles in the control of synaptogenesis and neurotransmitter release, yet their regulation is poorly understood. In particular, the contribution of transmembrane auxiliary proteins, which profoundly shape the trafficking and gating of somatodendritic iGluRs, is unknown. Here we examined the influence of transmembrane AMPAR regulatory proteins (TARPs) on presynaptic AMPARs in cerebellar molecular layer interneurons (MLIs). 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a partial agonist at TARP-associated AMPARs, enhanced spontaneous GABA release in wild-type mice but not in stargazer mice that lack the prototypical TARP stargazin (γ-2). These findings were replicated in mechanically dissociated Purkinje cells with functional adherent synaptic boutons, demonstrating the presynaptic locus of modulation. In dissociated Purkinje cells from stargazer mice, AMPA was able to enhance mIPSC frequency, but only in the presence of the positive allosteric modulator cyclothiazide. Thus, ordinarily, presynaptic AMPARs are unable to enhance spontaneous release without γ-2, which is required predominantly for its effects on channel gating. Presynaptic AMPARs are known to reduce action potential-driven GABA release from MLIs. Although a G-protein-dependent non-ionotropic mechanism has been suggested to underlie this inhibition, paradoxically we found that γ-2, and thus AMPAR gating, was required. Following glutamate spillover from climbing fibers or application of CNQX, evoked GABA release was reduced; in stargazer mice such effects were markedly attenuated in acute slices and abolished in the dissociated Purkinje cell-nerve bouton preparation. We suggest that γ-2 association, by increasing charge transfer, allows presynaptic AMPARs to depolarize the bouton membrane sufficiently to modulate both phasic and spontaneous release.
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18
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Kim Y, Lee SE, Park J, Kim M, Lee B, Hwang D, Chang S. ADP-ribosylation factor 6 (ARF6) bidirectionally regulates dendritic spine formation depending on neuronal maturation and activity. J Biol Chem 2015; 290:7323-35. [PMID: 25605715 DOI: 10.1074/jbc.m114.634527] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Recent studies have reported conflicting results regarding the role of ARF6 in dendritic spine development, but no clear answer for the controversy has been suggested. We found that ADP-ribosylation factor 6 (ARF6) either positively or negatively regulates dendritic spine formation depending on neuronal maturation and activity. ARF6 activation increased the spine formation in developing neurons, whereas it decreased spine density in mature neurons. Genome-wide microarray analysis revealed that ARF6 activation in each stage leads to opposite patterns of expression of a subset of genes that are involved in neuronal morphology. ARF6-mediated Rac1 activation via the phospholipase D pathway is the coincident factor in both stages, but the antagonistic RhoA pathway becomes involved in the mature stage. Furthermore, blocking neuronal activity in developing neurons using tetrodotoxin or enhancing the activity in mature neurons using picrotoxin or chemical long term potentiation reversed the effect of ARF6 on each stage. Thus, activity-dependent dynamic changes in ARF6-mediated spine structures may play a role in structural plasticity of mature neurons.
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Affiliation(s)
- Yoonju Kim
- From the Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Medical Research Center, Biomembrane Plasticity Research Center, and
| | - Sang-Eun Lee
- From the Department of Physiology and Biomedical Sciences, Biomembrane Plasticity Research Center, and
| | - Joohyun Park
- From the Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Medical Research Center, Biomembrane Plasticity Research Center, and
| | - Minhyung Kim
- School of Interdisciplinary Bioscience and Bioengineering and Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Kyungbook 790-784, South Korea, and
| | - Boyoon Lee
- Interdisciplinary Program in Neuroscience, Seoul National University College of Medicine, Seoul 110-799, South Korea
| | - Daehee Hwang
- School of Interdisciplinary Bioscience and Bioengineering and Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Kyungbook 790-784, South Korea, and Center for Systems Biology of Plant Senescence and Life History, Institute for Basic Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu, 711-873, South Korea
| | - Sunghoe Chang
- From the Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Medical Research Center, Biomembrane Plasticity Research Center, and Interdisciplinary Program in Neuroscience, Seoul National University College of Medicine, Seoul 110-799, South Korea,
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19
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Abstract
Secretory carrier membrane protein 5 (SCAMP5), a recently identified candidate gene for autism, is brain specific and highly abundant in synaptic vesicles (SVs), but its function is currently unknown. Here, we found that knockdown (KD) of endogenous SCAMP5 by SCAMP5-specific shRNAs in cultured rat hippocampal neurons resulted in a reduction in total vesicle pool size as well as in recycling pool size, but the recycling/resting pool ratio was significantly increased. SCAMP5 KD slowed endocytosis after stimulation, but impaired it severely during strong stimulation. We also found that KD dramatically lowered the threshold of activity at which SV endocytosis became unable to compensate for the ongoing exocytosis occurring during a stimulus. Reintroducing shRNA-resistant SCAMP5 reversed these endocytic defects. Therefore, our results suggest that SCAMP5 functions during high neuronal activity when a heavy load is imposed on endocytosis. Our data also raise the possibility that the reduction in expression of SCAMP5 in autistic patients may be related to the synaptic dysfunction observed in autism.
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20
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CRMP2 tethers kainate receptor activity to cytoskeleton dynamics during neuronal maturation. J Neurosci 2014; 33:18298-310. [PMID: 24227739 DOI: 10.1523/jneurosci.3136-13.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The CRMP2 and CRMP4 proteins are strongly expressed in the developing nervous system, mediating neurite outgrowth, neuronal polarity, and axon guidance. In the present study, we demonstrate the interaction of the CRMP2 and CRMP4 proteins with the GluK5 subunit of the kainate (KA) receptor (KAR) and investigated the role of KARs in modulating the development of cultured mouse DRG neurons. We found that KARs modulate neuronal maturation and neurite outgrowth in a bidirectional manner. Accordingly, low concentrations of KA delayed maturation and enhanced neurite outgrowth, whereas maturation was promoted by higher concentrations of KA that attenuated neuritic elongation. The effects of weak KAR activation were prevented by blocking their noncanonical signaling and involved a differential regulation of CRMP2. Whereas the delay in maturation involves PKC-mediated phosphorylation of CRMP2 at T555 leading to a downregulation of membrane Cav2.2, the promotion of neurite outgrowth is achieved by dephosphorylation at T514 at the growth cones, the latter reflecting PKC-driven enhancement of GSK3β phosphorylation at S9. Together, these findings indicate that noncanonical KAR signaling influences neuronal development by modulating CRMP2 activity.
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21
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Kloc M, Kubiak JZ, Li XC, Ghobrial RM. The newly found functions of MTOC in immunological response. J Leukoc Biol 2013; 95:417-30. [DOI: 10.1189/jlb.0813468] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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22
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USP47 and C terminus of Hsp70-interacting protein (CHIP) antagonistically regulate katanin-p60-mediated axonal growth. J Neurosci 2013; 33:12728-38. [PMID: 23904609 DOI: 10.1523/jneurosci.0698-13.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Katanin is a heterodimeric enzyme that severs and disassembles microtubules. While the p60 subunit has the enzyme activity, the p80 subunit regulates the p60 activity. The microtubule-severing activity of katanin plays an essential role in axonal growth. However, the mechanisms by which neuronal cells regulate the expression of katanin-p60 remains unknown. Here we showed that USP47 and C terminus of Hsp70-interacting protein (CHIP) antagonistically regulate the stability of katanin-p60 and thereby axonal growth. USP47 was identified as a katanin-p60-specific deubiquitinating enzyme for its stabilization. We also identified CHIP as a ubiquitin E3 ligase that promotes proteasome-mediated degradation of katanin-p60. Moreover, USP47 promoted axonal growth of cultured rat hippocampal neurons, whereas CHIP inhibited it. Significantly, treatment with basic fibroblast growth factor (bFGF), an inducer of axonal growth, increased the levels of USP47 and katanin-p60, but not CHIP. Consistently, bFGF treatment resulted in a marked decrease in the level of ubiquitinated katanin-p60 and thereby in the promotion of axonal growth. On the other hand, the level of USP47, but not CHIP, decreased concurrently with that of katanin-p60 as axons reached their target cells. These results indicate that USP47 plays a crucial role in the control of axonal growth during neuronal development by antagonizing CHIP-mediated katanin-p60 degradation.
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23
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Kim Y, Ha CM, Chang S. SNX26, a GTPase-activating protein for Cdc42, interacts with PSD-95 protein and is involved in activity-dependent dendritic spine formation in mature neurons. J Biol Chem 2013; 288:29453-66. [PMID: 24003235 DOI: 10.1074/jbc.m113.468801] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
SNX26, a brain-enriched RhoGAP, plays a key role in dendritic arborization during early neuronal development in the neocortex. In mature neurons, it is localized to dendritic spines, but little is known about its role in later stages of development. Our results show that SNX26 interacts with PSD-95 in dendritic spines of cultured hippocampal neurons, and as a GTPase-activating protein for Cdc42, it decreased the F-actin content in COS-7 cells and in dendritic spines of neurons. Overexpression of SNX26 resulted in a GTPase-activating protein activity-dependent decrease in total protrusions and spine density together with dramatic inhibition of filopodia-to-spine transformations. Such effects of SNX26 were largely rescued by a constitutively active mutant of Cdc42. Consistently, an shRNA-mediated knockdown of SNX26 significantly increased total protrusions and spine density, resulting in an increase in thin or stubby type spines at the expense of the mushroom spine type. Moreover, endogenous expression of SNX26 was shown to be bi-directionally modulated by neuronal activity. Therefore, we propose that in addition to its key role in neuronal development, SNX26 also has a role in the activity-dependent structural change of dendritic spines in mature neurons.
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Affiliation(s)
- Yoonju Kim
- From the Department of Physiology and Biomedical Sciences
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24
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LRRK2 phosphorylates Snapin and inhibits interaction of Snapin with SNAP-25. Exp Mol Med 2013; 45:e36. [PMID: 23949442 PMCID: PMC3789260 DOI: 10.1038/emm.2013.68] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 05/20/2013] [Accepted: 06/10/2013] [Indexed: 01/17/2023] Open
Abstract
Leucine-rich repeat kinase 2 (LRRK2) is a gene that, upon mutation, causes autosomal-dominant familial Parkinson's disease (PD). Yeast two-hybrid screening revealed that Snapin, a SNAP-25 (synaptosomal-associated protein-25) interacting protein, interacts with LRRK2. An in vitro kinase assay exhibited that Snapin is phosphorylated by LRRK2. A glutathione-S-transferase (GST) pull-down assay showed that LRRK2 may interact with Snapin via its Ras-of-complex (ROC) and N-terminal domains, with no significant difference on interaction of Snapin with LRRK2 wild type (WT) or its pathogenic mutants. Further analysis by mutation study revealed that Threonine 117 of Snapin is one of the sites phosphorylated by LRRK2. Furthermore, a Snapin T117D phosphomimetic mutant decreased its interaction with SNAP-25 in the GST pull-down assay. SNAP-25 is a component of the SNARE (Soluble NSF Attachment protein REceptor) complex and is critical for the exocytosis of synaptic vesicles. Incubation of rat brain lysate with recombinant Snapin T117D, but not WT, protein caused decreased interaction of synaptotagmin with the SNARE complex based on a co-immunoprecipitation assay. We further found that LRRK2-dependent phosphorylation of Snapin in the hippocampal neurons resulted in a decrease in the number of readily releasable vesicles and the extent of exocytotic release. Combined, these data suggest that LRRK2 may regulate neurotransmitter release via control of Snapin function by inhibitory phosphorylation.
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25
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Lordkipanidze T, Bikashvili T, Japaridze N, Zhvania M. The effect of kainic acid on hippocampal dendritic spine motility at the early and late stages of brain development. Micron 2013; 49:28-32. [PMID: 23548670 DOI: 10.1016/j.micron.2013.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 02/25/2013] [Accepted: 02/25/2013] [Indexed: 11/30/2022]
Abstract
Dendrites and spines undergo dynamic changes in physiological conditions, such as learning and memory, and in pathological conditions, such as epilepsy. Abnormalities in dendritic spines have commonly been observed in brain specimens from epilepsy patients and animal models of epilepsy. However, the functional implications and clinical consequences of this dendritic pathology for epilepsy are uncertain. Motility of dendritic spines and axonal filopodia has been recently discovered by the advanced imaging techniques, and remains to a large degree an exciting phenomenology in search of function. Here we demonstrate the effect of kainic acid (KA), which is a structural analog of glutamate, on dendritic spine motility in hippocampal CA1 area at the different stages of brain development. In order to reveal the changes that take place in spine and filopodial motility in the epileptic model of brain, time-lapse imaging of acute hippocampal slices treated with various concentrations of KA after different incubation time points was performed. The effects of KA exposure were tested on the slices from young (postnatal day (P)7-P10) and adolescent (P28-P30) Thy1-YFPH transgenic mice. Slices were treated with either 50 μM or 100 μM of KA, for either 30 or 100 min. The results obtained in our experiments show diverse effects of KA in 2 different age groups. According to our results, 100 μM/100 min KA treatment increases spine motility at early stage of brain development (P10) by 41.5%, while in P30 mice spine motility is increased only by 3%. Our findings also indicate that effect of KA on hippocampal dendritic spine motility is predominantly time- rather than concentration-dependent.
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26
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Park J, Jang M, Chang S. Deleterious effects of soluble amyloid-β oligomers on multiple steps of synaptic vesicle trafficking. Neurobiol Dis 2013; 55:129-39. [PMID: 23523634 DOI: 10.1016/j.nbd.2013.03.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 03/02/2013] [Accepted: 03/13/2013] [Indexed: 01/02/2023] Open
Abstract
Growing evidence supports a role for soluble amyloid-β oligomer intermediates in the synaptic dysfunction associated with Alzheimer's disease (AD), but the molecular mechanisms underlying this effect remain unclear. We found that acute treatment of cultured rat hippocampal neurons with nanomolar concentrations of Aβ oligomers reduced the recycling pool and increased the resting pool of synaptic vesicles. Endocytosis of synaptic vesicles and the regeneration of fusion-competent vesicles were also severely impaired. Furthermore, the release probability of the readily-releasable pool (RRP) was increased, and recovery of the RRP was delayed. All these effects were prevented by antibody against Aβ. Moreover reduction of the pool size was prevented by inhibiting calpain or CDK5, while the defects in endocytosis were averted by overexpressing phosphatidylinositol-4-phosphate-5-kinase type I-γ, indicating that these two downstream pathways are involved in Aβ oligomers-induced presynaptic dysfunction.
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Affiliation(s)
- Joohyun Park
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea
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27
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Jansson LC, Louhivuori L, Wigren HK, Nordström T, Louhivuori V, Castrén ML, Åkerman KE. Effect of glutamate receptor antagonists on migrating neural progenitor cells. Eur J Neurosci 2013; 37:1369-82. [PMID: 23383979 DOI: 10.1111/ejn.12152] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 01/10/2013] [Accepted: 01/10/2013] [Indexed: 02/03/2023]
Abstract
Neurotransmitters such as glutamate are potential regulators of neurogenesis. Interference with defined glutamate receptor subtypes affects proliferation, migration and differentiation of neural progenitor cells. The cellular targets for the actions of different glutamate receptor ligands are less well known. In this study we have combined calcium imaging, measurement of membrane potential, time-lapse imaging and immunocytochemistry to obtain a spatial overview of migrating mouse embryonic neural progenitor cell-derived cells responding to glutamate receptor agonists and antagonists. Responses via metabotropic glutamate receptor 5 correlated with radial glial cells and dominated in the inner migration zones close to the neurosphere. Block of metabotropic glutamate receptor 5 resulted in shorter radial glial processes, a transient increase in neuron-like cells emerging from the neurosphere and increased motility of neuron-like cells. α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors are present on the majority of migrating neuronal cells, which with time accumulate at the outer edge of the migration zone. Blocking these receptors leads to an enhanced extension of radial glial processes and a reduced motility of neuron-like cells. Our results indicate that functional glutamate receptors have profound effects on the motility of neural progenitor cells. The main target for metabotropic glutamate receptor 5 appears to be radial glial cells while AMPA/kainate receptors are mainly expressed in newborn neuronal cells and regulate the migratory progress of these cells. The results suggest that both metabotropic glutamate receptor 5 and AMPA/kainate receptors are of importance for the guidance of migrating embryonic progenitor cells.
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Affiliation(s)
- Linda C Jansson
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, University of Helsinki, Helsinki, Finland
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28
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Shifts in developmental timing, and not increased levels of experience-dependent neuronal activity, promote barrel expansion in the primary somatosensory cortex of rats enucleated at birth. PLoS One 2013; 8:e54940. [PMID: 23372796 PMCID: PMC3556040 DOI: 10.1371/journal.pone.0054940] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 12/17/2012] [Indexed: 11/19/2022] Open
Abstract
Birth-enucleated rodents display enlarged representations of whiskers (i.e., barrels of the posteromedial subfield) in the primary somatosensory cortex. Although the historical view maintains that barrel expansion is due to incremental increases in neuronal activity along the trigeminal pathway during postnatal development, recent evidence obtained in experimental models of intramodal plasticity challenges this view. Here, we re-evaluate the role of experience-dependent neuronal activity on barrel expansion in birth-enucleated rats by combining various anatomical methods and sensory deprivation paradigms. We show that barrels in birth-enucleated rats were already enlarged by the end of the first week of life and had levels of metabolic activity comparable to those in control rats at different ages. Dewhiskering after the postnatal period of barrel formation did not prevent barrel expansion in adult, birth-enucleated rats. Further, dark rearing and enucleation after barrel formation did not lead to expanded barrels in adult brains. Because incremental increases of somatosensory experience did not promote barrel expansion in birth-enucleated rats, we explored whether shifts of the developmental timing could better explain barrel expansion during the first week of life. Accordingly, birth-enucleated rats show earlier formation of barrels, accelerated growth of somatosensory thalamocortical afferents, and an earlier H4 deacetylation. Interestingly, when H4 deacetylation was prevented with a histone deacetylases inhibitor (valproic acid), barrel specification timing returned to normal and barrel expansion did not occur. Thus, we provide evidence supporting that shifts in developmental timing modulated through epigenetic mechanisms, and not increased levels of experience dependent neuronal activity, promote barrel expansion in the primary somatosensory cortex of rats enucleated at birth.
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29
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Gallo G. Mechanisms underlying the initiation and dynamics of neuronal filopodia: from neurite formation to synaptogenesis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 301:95-156. [PMID: 23317818 DOI: 10.1016/b978-0-12-407704-1.00003-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Filopodia are finger-like cellular protrusions found throughout the metazoan kingdom and perform fundamental cellular functions during development and cell migration. Neurons exhibit a wide variety of extremely complex morphologies. In the nervous system, filopodia underlie many major morphogenetic events. Filopodia have roles spanning the initiation and guidance of neuronal processes, axons and dendrites to the formation of synaptic connections. This chapter addresses the mechanisms of the formation and dynamics of neuronal filopodia. Some of the major lessons learned from the study of neuronal filopodia are (1) there are multiple mechanisms that can regulate filopodia in a context-dependent manner, (2) that filopodia are specialized subcellular domains, (3) that filopodia exhibit dynamic membrane recycling which also controls aspects of filopodial dynamics, (4) that neuronal filopodia contain machinery for the orchestration of the actin and microtubule cytoskeleton, and (5) localized protein synthesis contributes to neuronal filopodial dynamics.
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Affiliation(s)
- Gianluca Gallo
- Shriners Hospitals Pediatric Research Center, Center for Neural Repair and Rehabilitation, Department of Anatomy and Cell Biology, Temple University, Philadelphia, PA, USA.
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30
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Activity-dependent modulation of the interaction between CaMKIIα and Abi1 and its involvement in spine maturation. J Neurosci 2012; 32:13177-88. [PMID: 22993434 DOI: 10.1523/jneurosci.2257-12.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Remodeling of dendritic spines through regulation of actin dynamics is a key event in activity-dependent structural plasticity. However, the molecular mechanism underlying this process is poorly understood. Here, we show that activity-dependent modulation of Abl interactor 1-Ca(2+)/calmodulin-dependent kinase IIα (Abi1-CaMKIIα) interaction, and thereby their activity, is important for regulation of spine morphology in cultured rat hippocampal neurons. Abi1 interacts with CaMKIIα at resting conditions through Abi1's tSNARE (target membrane-associated SNARE), which harbors striking homology with CaMKIIα regulatory domain. The interaction of the two proteins, Abi1 and CaMKIIα, results in their simultaneous inhibition, inhibition of CaMKIIα activity, and also inhibition of Abi1-dependent Rac activation. Their functional impediment is released when they dissociate from each other by calmodulin binding through glutamate receptor activation. Before dissociation, Abi1 is phosphorylated by CaMKIIα at serine 88, which may involve in regulation of Rac activation and spine maturation. Our results suggest that modulation of the interaction between Abi1 and CaMKIIα, through the glutamate receptor pathway, may be a molecular mechanism underlying activity-regulated structural plasticity in rat hippocamapal neurons.
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Fu Y, Wu X, Lu J, Huang ZJ. Presynaptic GABA(B) Receptor Regulates Activity-Dependent Maturation and Patterning of Inhibitory Synapses through Dynamic Allocation of Synaptic Vesicles. Front Cell Neurosci 2012; 6:57. [PMID: 23227002 PMCID: PMC3512030 DOI: 10.3389/fncel.2012.00057] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 11/12/2012] [Indexed: 11/13/2022] Open
Abstract
Accumulating evidence indicate that GABA regulates activity-dependent development of inhibitory synapses in the vertebrate brain, but the underlying mechanisms remain unclear. Here we combined live imaging of cortical GABAergic axons with single cell genetic manipulation to dissect the role of presynaptic GABAB receptors (GABABRs) in inhibitory synapse formation in mouse. Developing GABAergic axons form a significant number of transient boutons but only a subset was stabilized. Synaptic vesicles in these nascent boutons are often highly mobile in the course of tens of minutes. Activation of presynaptic GABABRs stabilized mobile vesicles in nascent boutons through the local enhancement of actin polymerization. Inactivation of GABABRs in developing basket interneurons resulted in aberrant pattern of bouton size distribution, reduced bouton density and reduced axon branching, as well as reduced frequency of miniature inhibitory currents in postsynaptic pyramidal neurons. These results suggest that GABABRs along developing inhibitory axons act as a local sensor of GABA release and promote presynaptic maturation through increased recruitment of mobile vesicle pools. Such release-dependent validation and maturation of nascent terminals is well suited to sculpt the pattern of synapse formation and distribution along axon branches.
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Affiliation(s)
- Yu Fu
- Cold Spring Harbor Laboratory Cold Spring Harbor, NY, USA ; Program in Neuroscience, Stony Brook University Stony Brook, NY, USA
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Berry CT, Sceniak MP, Zhou L, Sabo SL. Developmental up-regulation of vesicular glutamate transporter-1 promotes neocortical presynaptic terminal development. PLoS One 2012; 7:e50911. [PMID: 23226425 PMCID: PMC3511412 DOI: 10.1371/journal.pone.0050911] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 10/26/2012] [Indexed: 11/19/2022] Open
Abstract
Presynaptic terminal formation is a complex process that requires assembly of proteins responsible for synaptic transmission at sites of axo-dendritic contact. Accumulation of presynaptic proteins at developing terminals is facilitated by glutamate receptor activation. Glutamate is loaded into synaptic vesicles for release via the vesicular glutamate transporters VGLUT1 and VGLUT2. During postnatal development there is a switch from predominantly VGLUT2 expression to high VGLUT1 and low VGLUT2, raising the question of whether the developmental increase in VGLUT1 is important for presynaptic development. Here, we addressed this question using confocal microscopy and quantitative immunocytochemistry in primary cultures of rat neocortical neurons. First, in order to understand the extent to which the developmental switch from VGLUT2 to VGLUT1 occurs through an increase in VGLUT1 at individual presynaptic terminals or through addition of VGLUT1-positive presynaptic terminals, we examined the spatio-temporal dynamics of VGLUT1 and VGLUT2 expression. Between 5 and 12 days in culture, the percentage of presynaptic terminals that expressed VGLUT1 increased during synapse formation, as did expression of VGLUT1 at individual terminals. A subset of VGLUT1-positive terminals also expressed VGLUT2, which decreased at these terminals. At individual terminals, the increase in VGLUT1 correlated with greater accumulation of other synaptic vesicle proteins, such as synapsin and synaptophysin. When the developmental increase in VGLUT1 was prevented using VGLUT1-shRNA, the density of presynaptic terminals and accumulation of synapsin and synaptophysin at terminals were decreased. Since VGLUT1 knock-down was limited to a small number of neurons, the observed effects were cell-autonomous and independent of changes in overall network activity. These results demonstrate that up-regulation of VGLUT1 is important for development of presynaptic terminals in the cortex.
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Affiliation(s)
- Corbett T. Berry
- Departments of Pharmacology and Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Michael P. Sceniak
- Departments of Pharmacology and Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Louie Zhou
- Departments of Pharmacology and Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Shasta L. Sabo
- Departments of Pharmacology and Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- * E-mail:
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Greif KF, Asabere N, Lutz GJ, Gallo G. Synaptotagmin-1 promotes the formation of axonal filopodia and branches along the developing axons of forebrain neurons. Dev Neurobiol 2012; 73:27-44. [PMID: 22589224 DOI: 10.1002/dneu.22033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Revised: 04/29/2012] [Accepted: 05/08/2012] [Indexed: 01/01/2023]
Abstract
Synaptotagmin-1 (syt1) is a Ca(2+)-binding protein that functions in regulation of synaptic vesicle exocytosis at the synapse. Syt1 is expressed in many types of neurons well before synaptogenesis begins both in vivo and in vitro. To determine if expression of syt1 has a functional role in neuronal development before synapse formation, we examined the effects of syt1 overexpression and knockdown on the growth and branching of the axons of cultured primary embryonic day 8 chicken forebrain neurons. In vivo these neurons express syt1, and most have not yet extended axons. We present evidence that syt1 plays a role in regulating axon branching, while not regulating overall axon length. To study the effects of overexpression of syt1, we used adenovirus-mediated infection to introduce a syt1-YFP construct, or control GFP construct, into neurons. Syt1 levels were reduced using RNA interference. Overexpression of syt1 increased the formation of axonal filopodia and branches. Conversely, knockdown of syt1 decreased the number of axonal filopodia and branches. Time-lapse analysis of filopodial dynamics in syt1-overexpressing cells demonstrated that elevation of syt1 levels increased both the frequency of filopodial initiation and their lifespan. Taken together these data indicate that syt1 regulates the formation of axonal filopodia and branches before engaging in its conventional functions at the synapse.
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Affiliation(s)
- Karen F Greif
- Department of Biology, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, USA.
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Ha CM, Park D, Han JK, Jang JI, Park JY, Hwang EM, Seok H, Chang S. Calcyon forms a novel ternary complex with dopamine D1 receptor through PSD-95 protein and plays a role in dopamine receptor internalization. J Biol Chem 2012; 287:31813-22. [PMID: 22843680 DOI: 10.1074/jbc.m112.370601] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcyon, once known for interacting directly with the dopamine D(1) receptor (D(1)DR), is implicated in various neuropsychiatric disorders including schizophrenia, bipolar disorder, and attention deficit hyperactivity disorder. Although its direct interaction with D(1)DR has been shown to be misinterpreted, it still plays important roles in D(1)DR signaling. Here, we found that calcyon interacts with the PSD-95 and subsequently forms a ternary complex with D(1)DR through PSD-95. Calcyon is phosphorylated on Ser-169 by the PKC activator phorbol 12-myristate 13-acetate or by the D(1)DR agonist SKF-81297, and its phosphorylation increases its association with PSD-95 and recruitment to the cell surface. Interestingly, the internalization of D(1)DR at the cell surface was enhanced by phorbol 12-myristate 13-acetate and SKF-81297 in the presence of calcyon, but not in the presence of its S169A phospho-deficient mutant, suggesting that the phosphorylation of calcyon and the internalization of the surface D(1)DR are tightly correlated. Our results suggest that calcyon regulates D(1)DR trafficking by forming a ternary complex with D(1)DR through PSD-95 and thus possibly linking glutamatergic and dopamine receptor signalings. This also raises the possibility that a novel ternary complex could represent a potential therapeutic target for the modulation of related neuropsychiatric disorders.
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Affiliation(s)
- Chang Man Ha
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea.
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Lee S, Jung KJ, Jung HS, Chang S. Dynamics of multiple trafficking behaviors of individual synaptic vesicles revealed by quantum-dot based presynaptic probe. PLoS One 2012; 7:e38045. [PMID: 22666444 PMCID: PMC3362565 DOI: 10.1371/journal.pone.0038045] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 05/02/2012] [Indexed: 11/26/2022] Open
Abstract
Although quantum dots (QDs) have provided invaluable information regarding the diffusive behaviors of postsynaptic receptors, their application in presynaptic terminals has been rather limited. In addition, the diffraction-limited nature of the presynaptic bouton has hampered detailed analyses of the behaviors of synaptic vesicles (SVs) at synapses. Here, we created a quantum-dot based presynaptic probe and characterized the dynamic behaviors of individual SVs. As previously reported, the SVs exhibited multiple exchanges between neighboring boutons. Actin disruption induced a dramatic decrease in the diffusive behaviors of SVs at synapses while microtubule disruption only reduced extrasynaptic mobility. Glycine-induced synaptic potentiation produced significant increases in synaptic and inter-boutonal trafficking of SVs, which were NMDA receptor- and actin-dependent while NMDA-induced synaptic depression decreased the mobility of the SVs at synapses. Together, our results show that sPH-AP-QD revealed previously unobserved trafficking properties of SVs around synapses, and the dynamic modulation of SV mobility could regulate presynaptic efficacy during synaptic activity.
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Affiliation(s)
- Suho Lee
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea
- Neuroscience Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, South Korea
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, South Korea
| | - Kyung Jin Jung
- Division of Electron Microscopic research, Korea Basic Science Institute, Daejeon, South Korea
| | - Hyun Suk Jung
- Division of Electron Microscopic research, Korea Basic Science Institute, Daejeon, South Korea
| | - Sunghoe Chang
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea
- Neuroscience Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, South Korea
- Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul, South Korea
- Bio-Max Institute, Seoul National University College of Medicine, Seoul, South Korea
- * E-mail:
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Menna E, Fossati G, Scita G, Matteoli M. From filopodia to synapses: the role of actin-capping and anti-capping proteins. Eur J Neurosci 2012; 34:1655-62. [PMID: 22103422 DOI: 10.1111/j.1460-9568.2011.07897.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Actin-capping and anti-capping proteins are crucial regulators of actin dynamics. Recent studies have indicated that these proteins may be heavily involved in all stages of synaptogenesis, from the emergence of filopodia, through neuritogenesis and synaptic contact stabilization, to the structural changes occurring at the synapse during potentiation phenomena. In this review, we focus on recent evidence pointing to an active role of actin-capping and anti-capping proteins in orchestrating the processes controlling neuronal connectivity and plasticity.
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Affiliation(s)
- Elisabetta Menna
- Department of Medical Pharmacology and CNR Institute of Neuroscience, University of Milan, Milano, Italy
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Gelsomino G, Menna E, Antonucci F, Rodighiero S, Riganti L, Mulle C, Benfenati F, Valtorta F, Verderio C, Matteoli M. Kainate Induces Mobilization of Synaptic Vesicles at the Growth Cone through the Activation of Protein Kinase A. Cereb Cortex 2012; 23:531-41. [DOI: 10.1093/cercor/bhs026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Park J, Kim Y, Park ZY, Park D, Chang S. Neuronal specific βPix-b stimulates actin-dependent processes via the interaction between its PRD and WH1 domain of N-WASP. J Cell Physiol 2012; 227:1476-84. [PMID: 21618538 DOI: 10.1002/jcp.22863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
βPix, a Pak-interacting nucleotide exchange factor (Cool-1/p85SPR), is a Cdc42/Rac1-specific guanine nucleotide exchange factor (GEF) involved in various actin-related processes. Many previous studies have focused on ubiquitously expressed βPix-a, while the role of the neuronal-specific isoform βPix-b is still unknown, especially whether its role is distinct from or similar to βPix-a. Here we show that unlike βPix-a, overexpression of βPix-b stimulates actin-dependent comet formation in BHK21 cells. This effect is attributed to the interaction between its proline-rich domain (PRD) and the WH1 domain of N-WASP. In addition, we show that overexpression of βPix-b stimulates actin-dependent dendritic spine formation in rat hippocampal neurons in culture, a formation that is blocked by co-expression of the WH1 domain of N-WASP or the PRD of βPix-b. Knocking-down endogenous expression of βPix-b by shRNA reduced the number of dendritic spines, which were rescued only by PRD-containing βPix-b mutants. GEF activity of βPix-b is also required for these effects. The results show that neuronal-specific βPix-b stimulates actin-dependent processes in cells via the interaction between its PRD and the WH1 domain of N-WASP. Our results identify N-WASP as the first protein shown to interact with the PRD of βPix-b, raising the possibility that, as an N-WASP WH1-binding protein, βPix-b may regulate N-WASP's activity in cells.
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Affiliation(s)
- Joohyun Park
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea
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39
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Network, cellular, and molecular mechanisms underlying long-term memory formation. Curr Top Behav Neurosci 2012; 15:73-115. [PMID: 22976275 DOI: 10.1007/7854_2012_229] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The neural network stores information through activity-dependent synaptic plasticity that occurs in populations of neurons. Persistent forms of synaptic plasticity may account for long-term memory storage, and the most salient forms are the changes in the structure of synapses. The theory proposes that encoding should use a sparse code and evidence suggests that this can be achieved through offline reactivation or by sparse initial recruitment of the network units. This idea implies that in some cases the neurons that underwent structural synaptic plasticity might be a subpopulation of those originally recruited; However, it is not yet clear whether all the neurons recruited during acquisition are the ones that underwent persistent forms of synaptic plasticity and responsible for memory retrieval. To determine which neural units underlie long-term memory storage, we need to characterize which are the persistent forms of synaptic plasticity occurring in these neural ensembles and the best hints so far are the molecular signals underlying structural modifications of the synapses. Structural synaptic plasticity can be achieved by the activity of various signal transduction pathways, including the NMDA-CaMKII and ACh-MAPK. These pathways converge with the Rho family of GTPases and the consequent ERK 1/2 activation, which regulates multiple cellular functions such as protein translation, protein trafficking, and gene transcription. The most detailed explanation may come from models that allow us to determine the contribution of each piece of this fascinating puzzle that is the neuron and the neural network.
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40
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Kudryashova IV. Structural and functional modifications of presynaptic afferents: Do they correlate with learning mechanisms? NEUROCHEM J+ 2011. [DOI: 10.1134/s181971241104009x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Joseph DJ, Williams DJ, MacDermott AB. Modulation of neurite outgrowth by activation of calcium-permeable kainate receptors expressed by rat nociceptive-like dorsal root ganglion neurons. Dev Neurobiol 2011; 71:818-35. [PMID: 21557511 PMCID: PMC3973019 DOI: 10.1002/dneu.20906] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Neurite outgrowth is a fundamental step in establishing proper neuronal connections in the developing central nervous system. Dynamic control of outgrowth has been attributed to changes in growth cone Ca2+ levels in response to extracellular cues. Here we have investigated a possible role for Ca2+ permeable kainate (KA) receptors in regulating neurite outgrowth of nociceptive-like dorsal root ganglion (DRG) neurons. To identify KA receptor subunits likely to be involved, we used quantitative RT-PCR on acutely dissociated DRG and dorsal horn neurons. DRG neurons expressed more GluK1, particularly the GluK1b spice variant, than dorsal horn neurons. Conversely, dorsal horn neurons expressed more GluK2, particularly GluK2a, than DRG neurons. Further, an RNA editing assay indicated that the majority of GluK1 and GluK2 mRNA transcripts in DRG were unedited. Imaging Ca2+ transients following application of a KA receptor agonist to DRG and dorsal horn co-cultures revealed increases in intracellular Ca2+ in the growth cones of DRG neurons. In the majority of cases, this increase in Ca2+ was partly or completely blocked by Joro spider toxin (JSTX), an antagonist for Ca2+-permeable AMPA and KA receptors. Treatment of DRG/dorsal horn co-cultures with KA for 18 hours suppressed neurite outgrowth while application of the rapidly desensitizing KA receptor agonist SYM 2081, the competitive AMPA/KA receptor antagonist, CNQX, and JSTX or philanthotoxin enhanced neurite outgrowth and prevented KA effects on neurite outgrowth. Thus, Ca2+ entry through KA receptors at the growth cone of DRG neurons may be an important regulator of neurite outgrowth.
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Affiliation(s)
- Donald J. Joseph
- Program in Neurobiology and Behavior-Department of Neuroscience, Columbia University, New York, NY 10032
| | - Damian J. Williams
- Department of Physiology and Biophysics, Columbia University, New York, NY 10032
| | - Amy B. MacDermott
- Program in Neurobiology and Behavior-Department of Neuroscience, Columbia University, New York, NY 10032
- Department of Physiology and Biophysics, Columbia University, New York, NY 10032
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Yang G, Liu Y, Yang K, Liu R, Zhu S, Coquinco A, Wen W, Kojic L, Jia W, Cynader M. Isoform-specific palmitoylation of JNK regulates axonal development. Cell Death Differ 2011; 19:553-61. [PMID: 21941371 DOI: 10.1038/cdd.2011.124] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The c-jun N-terminal kinase (JNK) proteins are encoded by three genes (Jnk1-3), giving rise to 10 isoforms in the mammalian brain. The differential roles of JNK isoforms in neuronal cell death and development have been noticed in several pathological and physiological contexts. However, the mechanisms underlying the regulation of different JNK isoforms to fulfill their specific roles are poorly understood. Here, we report an isoform-specific regulation of JNK3 by palmitoylation, a posttranslational modification, and the involvement of JNK3 palmitoylation in axonal development and morphogenesis. Two cysteine residues at the COOH-terminus of JNK3 are required for dynamic palmitoylation, which regulates JNK3's distribution on the actin cytoskeleton. Expression of palmitoylation-deficient JNK3 increases axonal branching and the motility of axonal filopodia in cultured hippocampal neurons. The Wnt family member Wnt7a, a known modulator of axonal branching and remodelling, regulates the palmitoylation and distribution of JNK3. Palmitoylation-deficient JNK3 mimics the effect of Wnt7a application on axonal branching, whereas constitutively palmitoylated JNK3 results in reduced axonal branches and blocked Wnt7a induction. Our results demonstrate that protein palmitoylation is a novel mechanism for isoform-specific regulation of JNK3 and suggests a potential role of JNK3 palmitoylation in modulating axonal branching.
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Affiliation(s)
- G Yang
- College of Interdisciplinary Studies, University of British Columbia, Brain Research Centre, 2211 Wesbrook Mall, Vancouver, BC V6T2B5, Canada.
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LIU PQ, ZHU KQ. The Effects of Activity of Astrocytes on Neuron Dendritic Filopodia Motility*. PROG BIOCHEM BIOPHYS 2011. [DOI: 10.3724/sp.j.1206.2010.00497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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44
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Recovery from Retinal Lesions: Molecular Plasticity Mechanisms in Visual Cortex Far beyond the Deprived Zone. Cereb Cortex 2011; 21:2883-92. [DOI: 10.1093/cercor/bhr079] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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45
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Lee KM, Jo S, Kim H, Lee J, Park CS. Functional modulation of AMP-activated protein kinase by cereblon. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:448-55. [DOI: 10.1016/j.bbamcr.2011.01.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 12/23/2010] [Accepted: 01/03/2011] [Indexed: 11/15/2022]
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Kim Y, Park J, Song WJ, Chang S. Overexpression of Dyrk1A causes the defects in synaptic vesicle endocytosis. Neurosignals 2010; 18:164-72. [PMID: 21135538 DOI: 10.1159/000321994] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 10/12/2010] [Indexed: 11/19/2022] Open
Abstract
Trisomy 21-linked Dyrk1A (dual-specificity tyrosine phosphorylation-regulated kinase 1A) overexpression is implicated in pathogenic mechanisms underlying mental retardation in Down syndrome (DS). It is known to phosphorylate multiple substrates including endocytic proteins in vitro, but the functional consequence of Dyrk1A-mediated phosphorylation on endocytosis has never been investigated. Here, we show that overexpression of Dyrk1A causes defects in clathrin-mediated endocytosis and specifically, in the recruitment of endocytic proteins to clathrin-coated pits in fibroblasts. Synaptic vesicle endocytosis also significantly slowed down as a result of Dyrk1A overexpression in cultured hippocampal neurons. These effects are dependent on Dyrk1A kinase activity. The inhibitory effect of Dyrk1A on synaptic vesicle endocytosis was confirmed in neuronal cultures derived from transgenic mice overexpressing Dyrk1A at levels found in DS. Pharmacological blockade of Dyrk1A with epigallocatechin gallate rescued the endocytic phenotypes found in transgenic neurons. Together, our results suggest that aberrant Dyrk1A-mediated phosphorylation of the endocytic machinery perturbs synaptic vesicle endocytosis, which may contribute to synaptic dysfunctions and cognitive deficits associated with DS.
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Affiliation(s)
- Yoonju Kim
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea
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Minamida S, Iwamura M, Kodera Y, Kawashima Y, Ikeda M, Okusa H, Fujita T, Maeda T, Baba S. Profilin 1 overexpression in renal cell carcinoma. Int J Urol 2010; 18:63-71. [PMID: 21091798 DOI: 10.1111/j.1442-2042.2010.02670.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To gain information about overexpressed antigens in renal cell carcinoma (RCC) by using a chemical proteomics approach. METHODS RCC cell line 769P was cultured and proteome analysis was subsequently carried out in the culture supernatants. By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and tandem mass spectrometry (LC-MS/MS), proteins in the culture supernatants were searched. A MEDLINE search to define the functions of the identified proteins was carried out. RESULTS Four differentially regulated proteins (profilin 1, amyloid beta A4 protein [APP], proprotein convertase subtilisin/kexin type 1 inhibitor [ProSAAS], galectin-3-binding protein [LGALS3BP]) were selected. These were not overexpressed in normal kidney tissue or reported in RCC. Their levels were measured through western blotting of normal kidney and RCC tissues. No differences were observed in the expression levels of APP, ProSAAS or LGALS3BP between RCC and normal kidney tissues. Profilin 1 was overexpressed in RCC tissue. On the basis of this observation, an immunohistochemical analysis of profilin 1 in normal kidney and RCC tissues was carried out. In normal tissues, tubules that were sources of RCC stained positive for profilin 1. In RCC tissue, in contrast, the stromal cells in the tumors stained positive. CONCLUSIONS Profilin 1 can be a key element in the pathological processes of RCC, such as tumorigenesis and/or tumor growth. Thus, it has the potential to serve as a diagnostic or progression biomarker and therapeutic target in RCC.
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Affiliation(s)
- Satoru Minamida
- Department of Urology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
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Synaptic activity and activity-dependent competition regulates axon arbor maturation, growth arrest, and territory in the retinotectal projection. J Neurosci 2010; 30:10939-51. [PMID: 20702722 DOI: 10.1523/jneurosci.1556-10.2010] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the retinotectal projection, synapses guide retinal ganglion cell (RGC) axon arbor growth by promoting branch formation and by selectively stabilizing branches. To ask whether presynaptic function is required for this dual role of synapses, we have suppressed presynaptic function in single RGCs using targeted expression of tetanus toxin light-chain fused to enhanced green fluorescent protein (TeNT-Lc:EGFP). Time-lapse imaging of singly silenced axons as they arborize in the tectum of zebrafish larvae shows that presynaptic function is not required for stabilizing branches or for generating an arbor of appropriate complexity. However, synaptic activity does regulate two distinct aspects of arbor development. First, single silenced axons fail to arrest formation of highly dynamic but short-lived filopodia that are a feature of immature axons. Second, single silenced axons fail to arrest growth of established branches and so occupy significantly larger territories in the tectum than active axons. However, if activity-suppressed axons had neighbors that were also silent, axonal arbors appeared normal in size. A similar reversal in phenotype was observed when single TeNT-Lc:EGFP axons are grown in the presence of the NMDA receptor antagonist MK801 [(+)-5-methyl-10,11- dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]. Although expansion of arbor territory is prevented when neighbors are silent, formation of transient filopodia is not. These results suggest that synaptic activity by itself regulates filopodia formation regardless of activity in neighboring cells but that the ability to arrest growth and focusing of axonal arbors in the target is an activity-dependent, competitive process.
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Zhuravlev PI, Der BS, Papoian GA. Design of active transport must be highly intricate: a possible role of myosin and Ena/VASP for G-actin transport in filopodia. Biophys J 2010; 98:1439-48. [PMID: 20409462 DOI: 10.1016/j.bpj.2009.12.4325] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 12/24/2022] Open
Abstract
Recent modeling of filopodia--the actin-based cell organelles employed for sensing and motility--reveals that one of the key limiting factors of filopodial length is diffusional transport of G-actin monomers to the polymerizing barbed ends. We have explored the possibility of active transport of G-actin by myosin motors, which would be an expected biological response to overcome the limitation of a diffusion-based process. We found that in a straightforward implementation of active transport the increase in length was unimpressive, < or = 30%, due to sequestering of G-actin by freely diffusing motors. However, artificially removing motor sequestration reactions led to approximately threefold increases in filopodial length, with the transport being mainly limited by the motors failing to detach from the filaments near the tip, clogging the cooperative conveyer belt dynamics. Making motors sterically transparent led to a qualitative change of the dynamics to a different regime of steady growth without a stationary length. Having identified sequestration and clogging as ubiquitous constraints to motor-driven transport, we devised and tested a speculative means to sidestep these limitations in filopodia by employing cross-linking and putative scaffolding roles of Ena/VASP proteins. We conclude that a naïve design of molecular-motor-based active transport would almost always be inefficient--an intricately organized kinetic scheme, with finely tuned rate constants, is required to achieve high-flux transport.
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Affiliation(s)
- Pavel I Zhuravlev
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina, USA
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Kuo TY, Chen CY, Hsueh YP. Bcl11A/CTIP1 mediates the effect of the glutamate receptor on axon branching and dendrite outgrowth. J Neurochem 2010; 114:1381-92. [PMID: 20534004 DOI: 10.1111/j.1471-4159.2010.06852.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While neuronal activity regulates neurite outgrowth and branching, the details of the underlying mechanisms are still largely unclear. This study investigated the effect of the glutamate receptors on neuritogenesis using cultured hippocampal neurons. At 3-4 days in vitro, NMDA treatment promoted axon branching but not primary axon extension. In contrast, blockade of the NMDA receptor (NMDAR) by AP5 treatment enhanced primary axon extension. NMDAR activation also increased dendrite number and total dendrite length. These results suggest that NMDAR controls axon and dendrite morphogenesis. A previous study demonstrated that knockdown of the zinc finger transcription factor B cell lymphoma 11A-long (Bcl11A-L) reduces deleted in colorectal cancer (DCC) and microtubule-associated protein (MAP) 1b expression, thereby promoting axon branching. Here, glutamate stimulation down-regulated the levels of the Bcl11A-L, DCC, MAP1b, and MAP2c proteins. Over-expression of either Bcl11A-L or DCC countered the effect of NMDA or glutamate on axon branching and dendrite outgrowth, indicating that the Bcl11A-L/DCC pathway is an important downstream effector of glutamate receptors in neurite arborization. Because knockdown of Bcl11A-L did not down-regulate MAP2c, our results suggest that glutamate receptors also use a Bcl11A-L-independent pathway to control dendrite outgrowth. To summarize, this study reveals novel pathways downstream of glutamate receptors that regulate axon and dendrite arborization.
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Affiliation(s)
- Ting-Yu Kuo
- The Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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