Regulation of F-Actin Stability in Dendritic Spines by Glutamate Receptors and Calcineurin

Neuronal degeneration and cell death can result from excessive activation of receptors for the excitatory neurotransmitter glutamate; however, the very earliest changes in cytoskeletal organization have not been well documented. We have used an in vitro model system to examine the early consequences of intense glutamate receptor activation on dendritic spine synapses. Cultured hippocampal neurons exposed to NMDA for as little as 5 min exhibited a rapid and extensive loss of dendritic spines. Staining for the presynaptic marker synapsin 1 and the postsynaptic density proteins PSD-95 and the NR1 subunit of NMDA receptors remained intact. The disappearance of spines was accompanied by a selective loss of filamentous actin staining at synapses. The NMDA-induced loss of spine actin was time- and concentration-dependent and blocked by NMDA receptor antagonists. The effect was mimicked by l-glutamate, AMPA, and ionomycin but not by agonists of L-type calcium channels or of metabotropic glutamate receptors. The effect of NMDA on local actin assembly was strongly attenuated by pretreatment with an actin stabilizing compound or by an antagonist of the calcium-dependent protein phosphatase calcineurin. Immunoreactivity for calcineurin was enriched at synapses together with F-actin. These results indicate that the actin-mediated stability of synaptic structure is disrupted by intense glutamate receptor activity and that calcineurin blockers may be useful in preventing such destabilization.

[1]  M. Fischer,et al.  Isoform Specificity in the Relationship of Actin to Dendritic Spines , 1997, The Journal of Neuroscience.

[2]  E. Sausville,et al.  Jasplakinolide, a cytotoxic natural product, induces actin polymerization and competitively inhibits the binding of phalloidin to F-actin. , 1994, The Journal of biological chemistry.

[3]  Y. Gillerot,et al.  [Mild Mental-retardation] , 1983 .

[4]  P. Ascher,et al.  Mechanosensitivity of NMDA receptors in cultured mouse central neurons , 1994, Neuron.

[5]  I. Spector,et al.  Latrunculins--novel marine macrolides that disrupt microfilament organization and affect cell growth: I. Comparison with cytochalasin D. , 1989, Cell motility and the cytoskeleton.

[6]  Catherine H. Horner,et al.  Plasticity of the dendritic spine , 1993, Progress in Neurobiology.

[7]  J. Cooper,et al.  Effects of cytochalasin and phalloidin on actin , 1987, The Journal of cell biology.

[8]  T. Bliss,et al.  Persistence of individual dendritic spines in living brain slices , 1992, Neuroreport.

[9]  J. Olney,et al.  Acute dendrotoxic changes in the hippocampus of kainate treated rats , 1979, Brain Research.

[10]  CE Jahr,et al.  Synaptic desensitization of NMDA receptors by calcineurin , 1995, Science.

[11]  G. Banker,et al.  An electron microscopic study of the development of axons and dendrites by hippocampal neurons in culture. II. Synaptic relationships , 1984, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[12]  P. Greengard,et al.  Activation of NMDA receptors induces dephosphorylation of DARPP-32 in rat striatal slices , 1990, Nature.

[13]  Stephen J. Smith,et al.  The Dynamics of Dendritic Structure in Developing Hippocampal Slices , 1996, The Journal of Neuroscience.

[14]  D. Choi,et al.  Glutamate receptors and the induction of excitotoxic neuronal death. , 1994, Progress in brain research.

[15]  E. Masliah,et al.  Quantitative synaptic alterations in the human neocortex during normal aging , 1993, Neurology.

[16]  M. Fischer,et al.  Rapid Actin-Based Plasticity in Dendritic Spines , 1998, Neuron.

[17]  I. Módy,et al.  Regulation of NMDA channel function by endogenous Ca2+-dependent phosphatase , 1994, Nature.

[18]  E. Masliah,et al.  Dendritic injury is a pathological substrate for human immunodeficiency virus—related cognitive disorders , 1997, Annals of neurology.

[19]  Mary B. Kennedy,et al.  The postsynaptic density at glutamatergic synapses , 1997, Trends in Neurosciences.

[20]  G. Banker,et al.  Characterization of GABAergic neurons in hippocampal cell cultures , 1994, Journal of neurocytology.

[21]  M. Mattson,et al.  Evidence That Actin Depolymerization Protects Hippocampal Neurons against Excitotoxicity by Stabilizing [Ca2+]i , 1995, Experimental Neurology.

[22]  S. Shorte.  N-methyl-D-aspartate evokes rapid net depolymerization of filamentous actin in cultured rat cerebellar granule cells. , 1997, Journal of neurophysiology.

[23]  Ann Marie Craig,et al.  Activity Regulates the Synaptic Localization of the NMDA Receptor in Hippocampal Neurons , 1997, Neuron.

[24]  R. Huganir,et al.  Selective clustering of glutamate and gamma-aminobutyric acid receptors opposite terminals releasing the corresponding neurotransmitters. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[25]  D. Purpura,et al.  Dendritic Spine "Dysgenesis" and Mental Retardation , 1974, Science.

[26]  J. Olney,et al.  Excitotoxicity and the NMDA receptor - still lethal after eight years , 1995, Trends in Neurosciences.

[27]  A. Craig,et al.  Role of Actin in Anchoring Postsynaptic Receptors in Cultured Hippocampal Neurons: Differential Attachment of NMDA versus AMPA Receptors , 1998, The Journal of Neuroscience.

[28]  M. Carlier,et al.  Control of actin dynamics in cell motility , 1999 .

[29]  Michael C. Bateman,et al.  Rapid Alterations in Dendrite Morphology during Sublethal Hypoxia or Glutamate Receptor Activation , 1996, Neurobiology of Disease.

[30]  I. Módy,et al.  The absence of a major Ca2+ signaling pathway in GABAergic neurons of the hippocampus. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[31]  K. Kosik,et al.  Calcineurin is associated with the cytoskeleton of cultured neurons and has a role in the acquisition of polarity. , 1993, Molecular biology of the cell.

[32]  W. Denk,et al.  Dendritic spines as basic functional units of neuronal integration , 1995, Nature.

[33]  S. B. Kater,et al.  Dendritic spines: cellular specializations imparting both stability and flexibility to synaptic function. , 1994, Annual review of neuroscience.

[34]  V. Fowler,et al.  Regulation of actin filament length in erythrocytes and striated muscle. , 1996, Current opinion in cell biology.

[35]  A. Scheibel,et al.  The Hippocampal‐Dentate Complex in Temporal Lobe Epilepsy , 1974, Epilepsia.

[36]  Richard G. Coss,et al.  Rapid dendritic spine stem shortening during one-trial learning: The honeybee's first orientation flight , 1982, Brain Research.

[37]  Christian Rosenmund,et al.  Calcium-induced actin depolymerization reduces NMDA channel activity , 1993, Neuron.

[38]  Ann Marie Craig,et al.  Competitive binding of α-actinin and calmodulin to the NMDA receptor , 1997, Nature.

[39]  F. Morrell,et al.  Age‐related loss of axospinous synapses formed by two afferent systems in the rat dentate gyrus as revealed by the unbiased stereological dissector technique , 1992, Hippocampus.

[40]  F. Dumont,et al.  The immunosuppressive and toxic effects of FK-506 are mechanistically related: pharmacology of a novel antagonist of FK-506 and rapamycin , 1992, The Journal of experimental medicine.

[41]  E. Quinlan,et al.  Postsynaptic Mechanisms for Bidirectional Control of MAP2 Phosphorylation by Glutamate Receptors , 1996, Neuron.

[42]  R. DeTeresa,et al.  Neocortical cell counts in normal human adult aging , 1987, Annals of neurology.

[43]  E Gould,et al.  Naturally occurring fluctuation in dendritic spine density on adult hippocampal pyramidal neurons , 1990, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[44]  M. Segal.  Morphological alterations in dendritic spines of rat hippocampal neurons exposed to N-methyl-d-aspartate , 1995, Neuroscience Letters.

[45]  J. Cooper.  The role of actin polymerization in cell motility. , 1991, Annual review of physiology.

[46]  G. Graveland,et al.  Evidence for degenerative and regenerative changes in neostriatal spiny neurons in Huntington's disease. , 1985, Science.

[47]  W. Brown,et al.  Analysis of neocortex in three males with the fragile X syndrome. , 1991, American journal of medical genetics.

[48]  A. Matus,et al.  High actin concentrations in brain dendritic spines and postsynaptic densities. , 1982, Proceedings of the National Academy of Sciences of the United States of America.

[49]  K. Harris,et al.  Variation in the number, location and size of synaptic vesicles provides an anatomical basis for the nonuniform probability of release at hippocampal CA1 synapses , 1995, Neuropharmacology.

[50]  P. Forscher,et al.  Novel form of growth cone motility involving site-directed actin filament assembly , 1992, Nature.

[51]  E. Fifková,et al.  Cytoplasmic actin in neuronal processes as a possible mediator of synaptic plasticity , 1982, The Journal of cell biology.

[52]  V. Fowler,et al.  Defining actin filament length in striated muscle: rulers and caps or dynamic stability? , 1998, Annual review of cell and developmental biology.

[53]  M. Segal.  Dendritic spines for neuroprotection: a hypothesis , 1995, Trends in Neurosciences.