Proteomic identification of phosphorylation dependent Septin 7 interactors that drive dendritic spine formation

Septins are a family of cytoskeletal proteins that regulate several important aspects of neuronal development. Septin 7 (Sept7) is enriched at the base of dendritic spines in excitatory neurons and mediates both spine formation and spine-synapse maturation. Phosphorylation at a conserved C-terminal tail residue of Sept7 mediates its translocation into the dendritic spine head to allow spine-synapse maturation. The mechanistic basis for postsynaptic stability and compartmentalization conferred by phosphorylated Sept7, however, is not known. We report herein the proteomic identification of Sept7 phosphorylation dependent neuronal interactors. Using Sept7 C-terminal phosphopeptide pulldown and biochemical assays, we show that the 14-3-3 family of proteins specifically interact with Sept7 when phosphorylated at the T426 residue. Biochemically, we validate the interaction between Sept7 and 14-3-3 isoform gamma, and show that 14-3-3 gamma is also enriched in mature dendritic spine head. Further, we demonstrate that interaction of phosphorylated Sept7 with 14-3-3 protects it from dephosphorylation, as expression of a 14-3-3 antagonist significantly decreases phosphorylated Sept7 in neurons. This study identifies 14-3-3 proteins as an important physiological regulator of Sept7 function in neuronal development.

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Rac GEF Dock4 interacts with cortactin to regulate dendritic spine formation

Molecular Biology of the Cell ◽

10.1091/mbc.e12-11-0782 ◽

2013 ◽

Vol 24 (10) ◽

pp. 1602-1613 ◽

Cited By ~ 30

Author(s):

Shuhei Ueda ◽

Manabu Negishi ◽

Hironori Katoh

Keyword(s):

Dendritic Spine ◽

Hippocampal Neurons ◽

Molecular Mechanisms ◽

Neuronal Development ◽

Actin Binding ◽

Spine Density ◽

Nucleotide Exchange ◽

Spine Formation ◽

Nucleotide Exchange Factor ◽

Important Interaction

In neuronal development, dendritic spine formation is important for the establishment of excitatory synaptic connectivity and functional neural circuits. Developmental deficiency in spine formation results in multiple neuropsychiatric disorders. Dock4, a guanine nucleotide exchange factor (GEF) for Rac, has been reported as a candidate genetic risk factor for autism, dyslexia, and schizophrenia. We previously showed that Dock4 is expressed in hippocampal neurons. However, the functions of Dock4 in hippocampal neurons and the underlying molecular mechanisms are poorly understood. Here we show that Dock4 is highly concentrated in dendritic spines and implicated in spine formation via interaction with the actin-binding protein cortactin. In cultured neurons, short hairpin RNA (shRNA)–mediated knockdown of Dock4 reduces dendritic spine density, which is rescued by coexpression of shRNA-resistant wild-type Dock4 but not by a GEF-deficient mutant of Dock4 or a truncated mutant lacking the cortactin-binding region. On the other hand, knockdown of cortactin suppresses Dock4-mediated spine formation. Taken together, the results show a novel and functionally important interaction between Dock4 and cortactin for regulating dendritic spine formation via activation of Rac.

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Differential localization of drebrin and fascin during dendritic spine formation

Neuroscience Research ◽

10.1016/s0168-0102(00)81379-6 ◽

2000 ◽

Vol 38 ◽

pp. S89

Author(s):

H Takahashi

Keyword(s):

Dendritic Spine ◽

Spine Formation ◽

Differential Localization

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Faculty Opinions recommendation of Rac GEF Dock4 interacts with cortactin to regulate dendritic spine formation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717992975.793477349 ◽

2013 ◽

Author(s):

Francine Benes ◽

Glenn Konopaske

Keyword(s):

Dendritic Spine ◽

Spine Formation

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Dendritic spine formation and pruning: common cellular mechanisms?

Trends in Neurosciences ◽

10.1016/s0166-2236(99)01499-x ◽

2000 ◽

Vol 23 (2) ◽

pp. 53-57 ◽

Cited By ~ 116

Author(s):

Menahem Segal ◽

Eduard Korkotian ◽

Diane D Murphy

Keyword(s):

Dendritic Spine ◽

Cellular Mechanisms ◽

Spine Formation

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The Phosphodiesterase 9 Inhibitor PF-04449613 Promotes Dendritic Spine Formation and Performance Improvement after Motor Learning

Developmental Neurobiology ◽

10.1002/dneu.22623 ◽

2018 ◽

Vol 78 (9) ◽

pp. 859-872 ◽

Cited By ~ 3

Author(s):

Baoling Lai ◽

Miao Li ◽

Wanling Hu ◽

Wei Li ◽

Wen-Biao Gan

Keyword(s):

Motor Learning ◽

Performance Improvement ◽

Dendritic Spine ◽

Spine Formation ◽

And Performance

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Stress and trauma: BDNF control of dendritic-spine formation and regression

Progress in Neurobiology ◽

10.1016/j.pneurobio.2013.10.005 ◽

2014 ◽

Vol 112 ◽

pp. 80-99 ◽

Cited By ~ 111

Author(s):

M.R. Bennett ◽

J. Lagopoulos

Keyword(s):

Dendritic Spine ◽

Spine Formation

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Insights into associative long-term potentiation from computational models of NMDA receptor-mediated calcium influx and intracellular calcium concentration changes

Journal of Neurophysiology ◽

10.1152/jn.1990.63.5.1148 ◽

1990 ◽

Vol 63 (5) ◽

pp. 1148-1168 ◽

Cited By ~ 104

Author(s):

W. R. Holmes ◽

W. B. Levy

Keyword(s):

Experimental Data ◽

Nmda Receptor ◽

Nmda Receptors ◽

Dendritic Spine ◽

Long Term Potentiation ◽

Input Frequency ◽

Spine Head ◽

Term Potentiation ◽

Concentration Changes

1. Because induction of associative long-term potentiation (LTP) in the dentate gyrus is thought to depend on Ca2+ influx through channels controlled by N-methyl-D-aspartate (NMDA) receptors, quantitative modeling was performed of synaptically mediated Ca2+ influx as a function of synaptic coactivation. The goal was to determine whether Ca2+ influx through NMDA-receptor channels was, by itself, sufficient to explain associative LTP, including control experiments and the temporal requirements of LTP. 2. Ca2+ influx through NMDA-receptor channels was modeled at a synapse on a dendritic spine of a reconstructed hippocampal dentate granule cell when 1-115 synapses on spines at different dendritic locations were activated eight times at frequencies of 10-800 Hz. The resulting change in [Ca2+] in the spine head was estimated from the Ca2+ influx with the use of a model of a dendritic spine that included Ca2+ buffers, pumps, and diffusion. 3. To use a compelling model of synaptic activation, we developed quantitative descriptions of the NMDA and non-NMDA receptor-mediated conductances consistent with available experimental data. The experimental data reported for NMDA and non-NMDA receptor-channel properties and data from other non-LTP experiments that separated the NMDA and non-NMDA receptor-mediated components of synaptic events proved to be limiting for particular synaptic variables. Relative to the non-NMDA glutamate-type receptors, 1) the unbinding of transmitter from NMDA receptors had to be slow, 2) the transition from the bound NMDA receptor-transmitter complex to the open channel state had to be even slower, and 3) the average number of NMDA-receptor channels at a single activated synapse on a single spine head that were open and conducting at a given moment in time had to be very small (usually less than 1). 4. With the use of these quantitative synaptic conductance descriptions. Ca2+ influx through NMDA-receptor channels at a synapse was computed for a variety of conditions. For a constant number of pulses, Ca2+ influx was calculated as a function of input frequency and the number of coactivated synapses. When few synapses were coactivated, Ca2+ influx was small, even for high-frequency activation. However, with larger numbers of coactivated synapses, there was a steep increase in Ca2+ influx with increasing input frequency because of the voltage-dependent nature of the NMDA receptor-mediated conductance. Nevertheless, total Ca2+ influx was never increased more than fourfold by increasing input frequency or the number of coactivated synapses.(ABSTRACT TRUNCATED AT 400 WORDS)

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