Synaptic Consolidation Normalizes AMPAR Quantal Size following MAGUK Loss

Levy, Jay M.; Chen, Xiaobing; Reese, Thomas S.; Nicoll, Roger A.

doi:10.1016/j.neuron.2015.07.015

Cited by 77 publications

(92 citation statements)

References 62 publications

(103 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 F1 and F2) were reduced ∼73% and ∼61%, respectively, after transfection with MAGUK miRNA, as normalized to simultaneously recorded control neurons. These reductions are quantitatively similar to those following viral transduction of the MAGUK miRNA in virally transduced hippocampal organotypic slice cultures (54). Furthermore, miniature EPSCs (mEPSCs) were examined to define the basis of the reduction in AMPAR transmission.…”

Section: Resultsmentioning

confidence: 66%

“…Interestingly, despite the rather ubiquitous distribution of MAGUKs at excitatory synapses, the reduction in synaptic AMPAR-mediated transmission appeared to be attributable primarily to an all-or-none loss of functional synapses. We present evidence that after the knockdown, there is an initial uniform decrease in AMPARs across all synapses, but over a 4-d period, a consolidation process in which a "winner-take-all" phenomenon occurs (54).…”

Section: Significancementioning

confidence: 83%

“…It is becoming clear that the MAGUK proteins have a central role in maintaining and anchoring glutamate receptors at the PSD (54). Here, we combined electrophysiological recording and advanced EM to evaluate the effects of simultaneous knockdown of three major MAGUK proteins on both synaptic function and the molecular organization of the PSD.…”

Section: Discussionmentioning

confidence: 99%

“…We have examined the consequences of knocking down three key MAGUKs on excitatory synaptic transmission and found an ∼80% reduction in both AMPAR and NMDAR synaptic responses (54). Interestingly, despite the rather ubiquitous distribution of MAGUKs at excitatory synapses, the reduction in synaptic AMPAR-mediated transmission appeared to be attributable primarily to an all-or-none loss of functional synapses.…”

Section: Significancementioning

confidence: 99%

See 3 more Smart Citations

PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density

Chen

Levy

Hou

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

252

201

View full text Add to dashboard Cite

The postsynaptic density (PSD)-95 family of membrane-associated guanylate kinases (MAGUKs) are major scaffolding proteins at the PSD in glutamatergic excitatory synapses, where they maintain and modulate synaptic strength. How MAGUKs underlie synaptic strength at the molecular level is still not well understood. Here, we explore the structural and functional roles of MAGUKs at hippocampal excitatory synapses by simultaneous knocking down PSD-95, PSD-93, and synapse-associated protein (SAP)102 and combining electrophysiology and transmission electron microscopic (TEM) tomography imaging to analyze the resulting changes. Acute MAGUK knockdown greatly reduces synaptic transmission mediated by α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) and N-methyl-D-aspartate receptors (NMDARs). This knockdown leads to a significant rise in the number of silent synapses, diminishes the size of PSDs without changes in pre-or postsynaptic membrane, and depletes the number of membraneassociated PSD-95-like vertical filaments and transmembrane structures, identified as AMPARs and NMDARs by EM tomography. The differential distribution of these receptor-like structures and dependence of their abundance on PSD size matches that of AMPARs and NMDARs in the hippocampal synapses. The loss of these structures following MAGUK knockdown tracks the reduction in postsynaptic AMPAR and NMDAR transmission, confirming the structural identities of these two types of receptors. These results demonstrate that MAGUKs are required for anchoring both types of glutamate receptors at the PSD and are consistent with a structural model where MAGUKs, corresponding to membraneassociated vertical filaments, are the essential structural proteins that anchor and organize both types of glutamate receptors and govern the overall molecular organization of the PSD.T he postsynaptic density (PSD) at excitatory glutamatergic synapses, appearing in electron micrographs as a prominent electron-dense thickening lining the postsynaptic membrane (1) is a complex macromolecular machine positioned across from synaptic vesicle release sites at the presynaptic active zone. The PSD clusters and organizes neurotransmitter receptors and signaling molecules at the postsynaptic membrane, transmits and processes synaptic signals, and can undergo structural changes to encode and store information (2-5). Two types of ionotropic glutamate receptors, AMPA receptors (AMPARs) and NMDA receptors (NMDARs), present at PSDs of excitatory synapses (6-10) mediate almost all synaptic transmission in the brain (11). Biochemistry and mass spectrometry of the detergent-extracted cellular fraction of PSDs have additionally identified many proteins associated with AMPAR and NMDAR complexes (12, 13).The membrane-associated guanylate kinases (MAGUKs), a class of abundant scaffold proteins consisting of PSD-95, PSD-93, synapse-associated protein (SAP)102, and SAP97, interact directly with NMDARs (14-18). These MAGUK proteins share conserved modular structures consisting of three...

show abstract

Section: Resultsmentioning

confidence: 66%

Section: Significancementioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

See 2 more Smart Citations

PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density

Chen

Levy

Hou

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

252

201

View full text Add to dashboard Cite

show abstract

“…Supporting the notion that PSD95 and SAP97 both interact with NMDARs are the findings that PSD95 and SAP97 in brain homogenate can interact in a domain-specific manner (42) and that SAP97 is complexed with NMDARs (43). However, simultaneous PSD95, PSD93, and SAP102 knockdown in a SAP97 knockout mouse line did not further decrease NMDAR currents (44), suggesting that SAP97 associations with NMDARs in PSDs are not essential. Alternatively, without PSD95, PSD93, and SAP102, loss of SAP97 may have no effect because PSD95, PSD93, and/or SAP102 is required for SAP97-NMDAR interactions.…”

Section: Discussionmentioning

confidence: 91%

Palmitoylation regulates glutamate receptor distributions in postsynaptic densities through control of PSD95 conformation and orientation

Jeyifous

Lin

Chen

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

Postsynaptic density protein 95 (PSD95) and synapse-associated protein 97 (SAP97) are homologous scaffold proteins with different N-terminal domains, possessing either a palmitoylation site (PSD95) or an L27 domain (SAP97). Here, we measured PSD95 and SAP97 conformation in vitro and in postsynaptic densities (PSDs) using FRET and EM, and examined how conformation regulated interactions with AMPA-type and NMDA-type glutamate receptors (AMPARs/NMDARs). Palmitoylation of PSD95 changed its conformation from a compact to an extended configuration. PSD95 associated with AMPARs (via transmembrane AMPAR regulatory protein subunits) or NMDARs [via glutamate ionotropic receptor NMDA-type subunit 2B (GluN2B) subunits] only in its palmitoylated and extended conformation. In contrast, in its extended conformation, SAP97 associates with NMDARs, but not with AMPARs. Within PSDs, PSD95 and SAP97 were largely in the extended conformation, but had different orientations. PSD95 oriented perpendicular to the PSD membrane, with its palmitoylated, N-terminal domain at the membrane. SAP97 oriented parallel to the PSD membrane, likely as a dimer through interactions of its N-terminal L27 domain. Changing PSD95 palmitoylation in PSDs altered PSD95 and AMPAR levels but did not affect NMDAR levels. These results indicate that in PSDs, PSD95 palmitoylation, conformation, and its interactions are dynamic when associated with AMPARs and more stable when associated with NMDARs. Altogether, our results are consistent with differential regulation of PSD95 palmitoylation in PSDs resulting from the clustering of palmitoylating and depalmitoylating enzymes into AMPAR nanodomains segregated away from NMDAR nanodomains.P ostsynaptic densities (PSDs) at glutamatergic synapses organize and hold NMDA receptors (NMDARs), AMPA receptors (AMPARs), and other signaling molecules in place, apposed to sites of neurotransmitter release. Just below the PSD plasma membrane lies a latticework of vertical and parallel filaments that provides a structural scaffold to stabilize synaptic signaling molecules within PSDs (1, 2). Postsynaptic density protein 95 (PSD95) and synapse-associated protein 97 (SAP97) are members of a family of membrane-associated guanylate kinases (MAGUKs) (3). PSD95 is the most abundant scaffold protein in adult synapses, with ∼300 PSD95 molecules (2.3% of the mass of the PSD) in the average PSD, and is part of the lattice forming the core of the PSD (4). SAP97 is also a component of the PSD lattice. Estimates of its PSD copy numbers range from 90 SAP97 molecules per average PSD [0.9% of the mass of the PSD (4)] to lower values (5). As MAGUKs, PSD95 and SAP97 share a series of highly homologous protein-interacting domains but diverge at their N-terminal domains, which affects their trafficking into and out of the PSD, as well as interactions with AMPARs and NMDARs (3, 6, 7). The SAP97β-isoform, like almost all SAP97 molecules, contains an N-terminal L27 domain that interacts with other L27 domaincontaining proteins, particularly with a differ...

show abstract

Protracted and asynchronous accumulation of PSD95‐family MAGUKs during maturation of nascent dendritic spines

Lambert

Hill

Park

et al. 2017

Developmental Neurobiology

View full text Add to dashboard Cite

The formation and stabilization of new dendritic spines is a key component of the experience-dependent neural circuit plasticity that supports learning, but the molecular maturation of nascent spines remains largely unexplored. The PSD95-family of membrane-associated guanylate kinases (PSD-MAGUKs), most notably PSD95, has a demonstrated role in promoting spine stability. However, nascent spines contain low levels of PSD95, suggesting that other members of the PSD-MAGUK family might act to stabilize nascent spines in the early stages of spiny synapse formation. Here, we used GFP-fusion constructs to quantitatively define the molecular composition of new spines, focusing on the PSD-MAGUK family. We found that PSD95 levels in new spines were as low as those previously associated with rapid subsequent spine elimination, and new spines did not achieve mature levels of PSD95 until between 12 and 20 h following new spine identification. Surprisingly, we found that the PSD-MAGUKs PSD93, SAP97, and SAP102 were also substantially less enriched in new spines. However, they accumulated in new spines more quickly than PSD95: SAP102 enriched to mature levels within 3 h, SAP97 and PSD93 enriched gradually over the course of 6 h. Intriguingly, when we restricted our analysis to only those new spines that persisted, SAP97 was the only PSD-MAGUK already present at mature levels in persistent new spines when first identified. Our findings uncover a key structural difference between nascent and mature spines, and suggest a mechanism for the stabilization of nascent spines through the sequential arrival of PSD-MAGUKs.

show abstract

Synaptic Consolidation Normalizes AMPAR Quantal Size following MAGUK Loss

Cited by 77 publications

References 62 publications

PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density

PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density

Palmitoylation regulates glutamate receptor distributions in postsynaptic densities through control of PSD95 conformation and orientation

Protracted and asynchronous accumulation of PSD95‐family MAGUKs during maturation of nascent dendritic spines

Contact Info

Product

Resources

About