Synaptopodin regulates spine plasticity: mediation by calcium stores

TY - JOUR

T1 - Synaptopodin regulates spine plasticity: mediation by calcium stores

AU - Korkotian, Eduard

AU - Frotscher, Michael

AU - Segal, Menahem

N1 - Copyright © 2014 the authors 0270-6474/14/3411641-11$15.00/0.

PY - 2014/8/27

Y1 - 2014/8/27

N2 - The role of synaptopodin (SP), an actin-binding protein residing in dendritic spines, in synaptic plasticity was studied in dissociated cultures of hippocampus taken from control and SP knock-out (SPKO) mice. Unlike controls, SPKO cultures were unable to express changes in network activity or morphological plasticity after intense activation of their NMDA receptors. SPKO neurons were transfected with SP-GFP, such that the only SP resident in these neurons is the fluorescent species. The localization and intensity of the transfected SP were similar to that of the native one. Because less than half of the spines in the transfected neurons contained SP, comparisons were made between SP-containing (SP(+)) and SP lacking (SP(-)) spines in the same dendritic segments. Synaptic plasticity was induced either in the entire network by facilitation of the activation of the NMDA receptor, or specifically by local flash photolysis of caged glutamate. After activation, spines that were endowed with SP puncta were much more likely to expand than SP(-) spines. The spine expansion was suppressed by thapsigargin, which disables calcium stores. The mechanism through which SP may promote plasticity is indicated by the observations that STIM-1, the sensor of calcium concentration in stores, and Orai-1, the calcium-induced calcium entry channel, are colocalized with SP, in the same dendritic spines. The structural basis of SP is likely to be the spine apparatus, found in control but not in SPKO cells. These results indicate that SP has an essential, calcium store-related role in regulating synaptic plasticity in cultured hippocampal neurons.

AB - The role of synaptopodin (SP), an actin-binding protein residing in dendritic spines, in synaptic plasticity was studied in dissociated cultures of hippocampus taken from control and SP knock-out (SPKO) mice. Unlike controls, SPKO cultures were unable to express changes in network activity or morphological plasticity after intense activation of their NMDA receptors. SPKO neurons were transfected with SP-GFP, such that the only SP resident in these neurons is the fluorescent species. The localization and intensity of the transfected SP were similar to that of the native one. Because less than half of the spines in the transfected neurons contained SP, comparisons were made between SP-containing (SP(+)) and SP lacking (SP(-)) spines in the same dendritic segments. Synaptic plasticity was induced either in the entire network by facilitation of the activation of the NMDA receptor, or specifically by local flash photolysis of caged glutamate. After activation, spines that were endowed with SP puncta were much more likely to expand than SP(-) spines. The spine expansion was suppressed by thapsigargin, which disables calcium stores. The mechanism through which SP may promote plasticity is indicated by the observations that STIM-1, the sensor of calcium concentration in stores, and Orai-1, the calcium-induced calcium entry channel, are colocalized with SP, in the same dendritic spines. The structural basis of SP is likely to be the spine apparatus, found in control but not in SPKO cells. These results indicate that SP has an essential, calcium store-related role in regulating synaptic plasticity in cultured hippocampal neurons.

KW - Animals

KW - Calcium

KW - Dendritic Spines

KW - Hippocampus

KW - Immunohistochemistry

KW - Mice

KW - Mice, Inbred C57BL

KW - Mice, Knockout

KW - Microfilament Proteins

KW - Microscopy, Confocal

KW - Neuronal Plasticity

KW - Patch-Clamp Techniques

KW - Synapses

KW - Transfection

U2 - 10.1523/JNEUROSCI.0381-14.2014

DO - 10.1523/JNEUROSCI.0381-14.2014

M3 - SCORING: Journal article

C2 - 25164660

VL - 34

SP - 11641

EP - 11651

JO - J NEUROSCI

JF - J NEUROSCI

SN - 0270-6474

IS - 35

ER -